What is the first word you said as a child?
What is the first book you have picked up and read?
Who is the first friend you have made?
Around what age did you take your first steps walking?
If you can’t remember the answer to at least one of these questions, don’t worry no need to kick yourself. It is impossible to remember every single moment of your early childhood from birth to the present.
Or is it?
You are surrounded by a plethora of information (sensory, general knowledge, media, stories, language, vocabulary etc.) and your brain has to process all of it. However, your brain would need a considerable amount of biological storage to stockpile all this information and recalling a specific memory for a specific task would take time and effort. There are a selection of humans who have incredible memory recall of the most obscure facts and trivia in a variety of general knowledge topics (notably history, humanities, music, entertainment, sport, science, politics, popular culture, leisure). They often participate in quizzing or trivia events such as the World Quizzing Championships and their respective local quizzing leagues and pub quizzing clubs. I have watched a lot of quiz shows ranging from The Chase, Who Wants To Be A Millionaire, Eggheads, Jeopardy, University Challenge and Mastermind. The most knowledgable quizmasters never cease to astound me with their immediate memory recall of a particular fact in order to answer quick-fire general knowledge questions within a second or two. Notable quizzers from each quiz show include:
Left to right: Jenny Ryan (Vixen); Mark Labbett (Beast); Anne Hegerty (Governess); Shaun Wallace (Dark Destroyer); Paul Sinha (Sinnerman)
Darragh Ennis (Menace)
— The Chase UK: Mark Labbett (The Beast), Shaun Wallace (The Dark Destroyer), Paul Sinha (The Sinnerman), Anne Hegerty (The Governess), Jenny Ryan (The Vixen), Darragh Ennis (The Menace).
Left to right: Brydon Coverdale (Shark), Issa Schultz (Supernerd), Cheryl Toh (Tiger Mum), Matt Parkinson (Goliath)
— The Chase Australia: Issa Schultz (Supernerd), Brydon Coverdale (Shark), Matt Parkinson (Goliath), Cheryl Toh (Tiger Mum)
Top row (left to right): Steve Cooke, Kevin Ashman, Pat Gibson, Chris Hughes
Bottom row (left to right): Judith Keppel, Lisa Thiel, Barry Simmons, Beth Webster, David Rainford
Left to right: Chris Hughes, Daphne Fowler, CJ De Mooi, Barry Simmons, Kevin Ashman, Judith Keppel
— Eggheads: Pat Gibson, Kevin Ashman, CJ De Mooi, David Rainford, Lisa Thiel, Judith Keppel, Beth Webster, Steve Cooke, Chris Hughes, Barry Simmonds, Daphne Fowler
— Honorary mentions: Gavin Fuller, David Edwards, Ian Bayley, Ken Jennings, John Carpenter, Dr. Trevor Sauer, Gary Grant
If I asked you to list out every single book, movie, TV show, song and cartoon you have consumed, we would be here until Christmas and it would be a mental struggle attempting to produce a comprehensive list aloud. However, if I pronounced the titles of such books, movies, TV shows, songs and cartoons to you, you would effortlessly indicate whether you have heard or consumed them or not. So why is this the case?
When people are asked about the most memorable moments of their lives, the common responses would include:
(i) Positive
— Birthdays
— New beginnings: School, University, Employment, Migration to new country
— Parties: Night clubs, Festivals, Dinner
— Firsts
— Performances
— New Purchases e.g. Car, House
— Births of newborn children
— Achievements, Accomplishments, Awards, Graduations, Triumphs, Promotions
— Holiday destinations
— Love, Sexual activities, Weddings
(ii) Negative
— Near-death experience
— Adrenaline rush
— Losing a loved one or pet
— Trauma / Torture
— Injury
— Loud sounds
— Fear
— Abuse: Sexual, Physical
— Controversy
— Smells
— Failures
— Murder stories
(iii) Neutral: Descriptions (Colour, Shape, Size)
— Name
— Age
— Birthday
— Pet(s)
— House(s)
— Names of family members and friends
— Address
— Phone Number
— Common vocabulary of first spoken language
— Personal belongings
— Daily routines
— Geographical locations
Here is a list of words I would like you to memorise:
- Galaxy, Track, Hostel, Elephant, Cucumber, Archery, Lumber, Gnome, Batter
Memory:
Thoughty2 video:
https://www.youtube.com/watch?v=_S-oRFB-qSE&ab_channel=Thoughty2
CrashCourse video:
https://www.youtube.com/watch?v=bSycdIx-C48&ab_channel=CrashCourse
TED video:
https://www.youtube.com/watch?v=PB2OegI6wvI&ab_channel=TED
Infographics Show video:
https://www.youtube.com/watch?v=43JDG0E5k4U&ab_channel=TheInfographicsShow
It’s Okay to be Smart video:
https://www.youtube.com/watch?v=TqFtWwQCzFI&ab_channel=It%27sOkayToBeSmart
What is memory?
https://en.wikipedia.org/wiki/Memory
How does memory work?
1. How is memory encoded?
https://en.wikipedia.org/wiki/Encoding_(memory)https://en.wikipedia.org/wiki/Learning_curve
https://www.semanticscholar.org/paper/%5BThe-brain-mechanism-of-memory-encoding-and-a-on-Wang-Mo/4367c8a885b449e78a8045435d005a74cdee11a8
 |
| Hermann Ebbinghaus (1850 - 1909) |
- Encoding is defined as the conversion of a perceived item of use or interest into a construct to be stored within the brain and recalled at a later time from long-term memory.
- This concept was first explored by famous philosophers such as Aristotle and Plato.
- Known as the pioneer of memory research, Hermann Ebbinghaus was an influential figure in the history of encoding.
- In 1885, he used himself as a subject to investigate the human neurological processes of learning and forgetting information through the action of reiterating a list of nonsense syllables to the metronome's rhythm until it consolidated as memories.
- The reason behind the use of relatively meaningless words is to limit the influence of prior associations between meaningful words on learning.
- His findings were lists permitting associations and apparent semantic meanings were effortlessly recalled, which paved the way for future experiments in psychology that study memory and other complex neurological processes. Furthermore, Ebbinghaus' experiments yielded a learning curve.
Throughout the late 19th and 20th century, the following scientists contributed to memory research:
- Ivan Pavlov (1897) = Classical conditioning
- Frederic Bartlett (1932) = Mental schemas
- Donald Hebb (1949) = Neurobiology of memory encoding
- George Armitage Miller (1956) = Short-term memory, The Magical Number Seven, Plus or Minus Two
- Alan Baddeley & Graham Hitch (1974) = Working memory model
- Endel Tulving (1983) = Encoding specificity
What are the different types of encoding?
There are 2 primary processes of coding information: physiological and mental. Parker et al. (2005) described the physiological process involved a neuron firing pattern in the brain that represented a memory, whereas the mental process involves the mind. The following list are the types of mental encoding:
i. Visual
- It converts mental images and visual sensory information to memory storage in the brain.
- Sperling (1963) suggested this information is temporarily stored within our iconic memory and working memory before being encoded into long-term memory.
- Baddeley et al. (2009) proposed a model of working memory in order explain how visual information stores in the brain region called the 'visuo-spatial sketchpad'. This region is linked to an important region of working memory called 'the central executive'.
- Belova et al. (2008) implied the amygdala plays a role since it receives visual input as well as input from other systems, then encodes the positive or negative values of conditioned stimuli.
ii. Elaborative
- It is the active process of associating new information to knowledge already existing in memory.
- Groome (2013) thought the nature of any memory relies on as much as old information currently stored in memory as it does on new information input through our senses. This means the level of deep thought applied relates to our ability to remember new information.
- Brown & Craik (2000) demonstrated elaborative encoding augments long-term retention of new information.
- It is the processing and encoding of sensory input with a certain meaning that can applied to a particular context.
- A study by Demb et al. (1995) found recall of words learned in semantic or deep encoding conditions improved compared to both easy and hard classifications of non-semantic or shallow encoding conditions.
- Neuroscientists discovered Brodmann's areas 45, 46 and 47 (the left inferior prefrontal cortex, LIPC) were highly active during semantic encoding conditions compared to non-semantic encoding conditions regardless of how difficult the non-semantic encoding task was.
- Furthermore, these same brain regions increase in activity during initial semantic encoding and decrease in activity during repetitive semantic encoding of the same words. This finding evinced that words are semantically reprocessed rather than non-semantically reprocessed.
- Lesion and neuroimaging studies by Frey & Petrides (2002) discovered the orbitofrontal cortex is involved in the initial encoding and the left lateral prefrontal cortex associates with the semantic assortment of encoded information.
iv. Acoustic
- It is the encoding of auditory impulses.
- Baddeley et al. (2009) hypothesised acoustic encoding occurs due to a phonological loop, which transfers acoustic input to our echoic memory. This is where acoustic information is vocally rehearsed to promote remembering.
- Carlson & Heth (2010) conveyed that words are audibly perceived as individual sounds, which indicated the memory of a novel's word first syllable is stored in our echoic memory until the entire sound stimulus has been perceived and recognised as a word.
- Studies suggested verbal working memory associates with lexical, semantic and phonological stimuli. Acheson et al. (2010) proposed a concept called the phonological similarity effect (PSE), which is moderated by concreteness of words. He argued verbal working memory associated with linguistic percepts, in addition to phonological and acoustic percepts.
- More research is required to determine the perception of linguistic input in terms of recall time and the manner which the stimulus was presented( e.g. video, recording, symbols) in the role of encoding and retaining acoustic memory.
- Hughes et al. (2016) suggested the brain hinged on acoustic encoding for short-term memory storage and semantic encoding for long-term memory storage.
Tactile encoding processes the stimuli we touch or feel via touch-sensitive receptors in the skin. Crawley et al. (1998) stated the primary somatosensory cortex (S1)
Describe the molecular processes of encoding
The molecular basis of encoding is poorly understood, however there have been progress in the understanding of such mechanisms. Wagner (2008) stated encoding initiates upon perception of any novel information and the brain subsequently integrates and processes the information, which trigger a cascade of molecular mechanisms that help develop new memories. This induces neurobiological effects such as regulation of neural synapses and proteins, development of new synapses, gene expression and protein synthesis. Rasch et al. (2006) discovered new memory encoding during wakefulness associated with increased acetylcholine levels throughout the central nervous system (CNS) , and memory consolidation during slow-wave sleep associated with decreased acetylcholine levels.
i. Synaptic Plasticity
- This process is the brain's ability to strengthen, weaken, remove and generate neural synapses, which forms the basis of learning.
- Since the effect of new learning experiences depends on the content of such experiences, positive reactions are reinforced and negative reactions are diminished.
- Kandel (2004) indicated that synaptic changes induce a combination of strengthening and weakening of synaptic connections by regulating the proteins that modulate synapse integrity.
ii. Biochemical Process
- This refers to the covalent transformation of proteins that regulate synaptic connections. This lead to the short-term encoding of information, prior to its consolidation to long-term memory.
- During this stage, certain short-term memories or connections are selected to either become long-term memories, or forgotten in the form of weakening synapses.
- Kandel (2004) found this mechanism is mediated by several inhibitory biochemicals, principally the balance between protein phosphorylation and dephosphorylation.
- Sacktor (2008) outlined the long-term changes fundamental to the target memory consolidation include new protein synthesis, synaptogenesis, and increased gene expression according to the new neural configuration.
- There are theories that the encoding process is partially mediated by serotonergic neurons, which associated with sensitisation, however more research is required.
iii. Genetics
- Twin studies conducted by Wagner (2008) found human memory is a heritable trait regulated by more than 1 gene, with as much as 50% of the performance variance in memory tasks determined by genetic differences.
- The study identified a genetic variant His452Tyr (rs6314) of the functional 5-HT2A serotonin receptor is associated with long-term memory. They suggested the 5-HT2A receptor is involved in memory consolidation.
- Studies that employed positron emission topography (PET) found the hippocampus is activated during episodic encoding and retrieval.
- Lepage et al. (1998) found the rostral part of the Amygdala associated with episodic memory, while the caudal part of the Amygdala associated with episodic memory retrieval.
- Grady et al. (1995) found the right hippocampus and the left prefrontal and temporal cortices associated with encoding, and the right prefrontal and parietal cortices associated with recognition in young children.
- Nonetheless, the aforementioned brain regions lacked activation in elderly people during encoding, except for the right prefrontal cortex during recognition tasks.
- This lead to the conclusion that ageing compromises not only existing memories but also the ability to encode stimuli into new memories.
- Birmes et al. (2002) found that in brains affected with post traumatic stress disorder (PTSD), glutamate and GABA (amino acid neurotransmitters) are associated with the encoding of factual memory, whereas adrenaline, noradrenaline and serotonin (amine neurotransmitters) are associated with the encoding of emotional memory.
- It is theorised the brain contains 2 complementary processing networks: task positive and task negative. The task positive network handles externally oriented processing, while the task negative network handles internally oriented processing.
- Cabeza et al. (2009) found marked overlap between encoding success and detection of novel activity within the task positive network, which may demonstrate a correlation with externally oriented processing.
- Furthermore, it demonstrates marked overlap between encoding failure and retrieval success within the task negative network, which suggests a correlation with internally oriented processing.
- Since there was little overlap between encoding success and retrieval success as well as between encoding failure and novelty detection respectively, this evinced opposite modes of processing.
- Craik & Lockhart (1972) conceptualised the idea that different levels of processing are required for the encoding of information into long-term memory.
- They described the encoding stage of memory formation process as 'shallow processing', since this stage is autonomous and required little conscious effort.
- Meanwhile, they defined 'deeper processing' as needing more attention exerted on the stimulus and more engagement from various cognitive systems to encode the information into memory.
- One exception of deeper processing they specified was repetitive exposure to the stimulus to the point of routine in an individual's life such as their name.
i. Maintenance and Elaborative Rehearsals
- Maintenance rehearsal is a form of shallow processing that involves concentrating on an object without applying thought to its definition or its connection with other objects. e.g. Repeating a series of numbers such as 15, 39, 47, 58, or phone numbers
- Elaborative / relational rehearsal is a form of deep processing that associate new information to knowledge already stored in long-term memory. It incorporates the object's value and establishes associations between the object, past experiences, and other objects of interest. e.g. Numbers associated with personally significant or memorable dates such as birthdays, weddings etc.
- Craikk & Watkins (1973) found elaborative rehearsals were more effective than maintenance rehearsals in forming novel memories, which demonstrated the participants' lack of knowledge of the details in everyday objects. e.g. Orientation of the face on the American penny.
- Studies found maintenance rehearsal exhibited moderate effectiveness in learning using indirect methods such as lexical decision tasks, and word stem completion.
ii. Intention to Learn
- Although there was no evidence to suggest that the intention to learn directly improved memory encoding, studies have found evidence that memory encoding relies on the deep processing on the object, which can be impacted by intention to learn.
- Nevertheless, the intention to learn can yield more effective learning strategies, and as a result, augment memory encoding. However, incidental learning can produce the same neurological outcomes assuming the processing and learning of the information is as effective.
Discuss the types of optimal encoding
a. Organisation
- Schunk (2012) found the brain innately organise information if the input is yet to be sorted. He theorised the mind uses hierarchies to organise new information being perceived.
- Katona (1940) suggested the depth of processing correlated with the level of organisation occurring within the mind.
b. Visual imagery
Bower & Winzenz (1970) found participants who produced visual imagery of the words demonstrated greater memory than those who employed maintenance rehearsal to memorise the same words. This implies visual imagery associations with words can augment memory encoding.
c. Mnemonics
- A 1968 report suggested the use of mnemonics to memorise list of words, or long phrases, whilst preserving existing knowledge in long-term memory.
- Examples of mnemonics include the peg-word system and acronyms.
- Example of an acronym = The colours of the rainbow from top to bottom - ROY G. BIV: Red, Orange, Yellow, Green, Blue, Indigo, Violet
- Example of a peg-word memory = 1 - Earth, 2 - Lungs, 3 - Seats, 4 - Golf, 5 - Hand, 6 - Runs, 7 - Planets, 8 - Octopus, 9 - Cat, 10 - Bullseye
d. Chunking
- This memory strategy involves maximising the amount of information stored in short-term memory in an attempt to integrate it into small, meaningful 'chunks'. These chunks are subsequently memorised as a unit rather than a separate components.
- Theoretically, information is combined into meaningful connections and incorporated into fewer, but larger chunks of information during the analysis and integration stage of the larger chunks of information. Goldstein & Bruce (2018) thought this advanced the amount of information encoded into short-term memory. In addition, they measured chunking improved recall of information such as numbers by up to factor of 4 and created as many associated between these items.
- Example of chunking is phone numbers, such as 1300655506 -> 1300 6 555 06
- Supercalifragilisticexpialodocious -> Super cali fragilistic ex pialo docious.
e. State-Dependent Learning
- To achieve optimal encoding, associations would need to created between the internal state or mood of the encoder and the situation they currently experience, in addition to the associations between the items and the past experiences.
- Godden & Baddeley (1975) found participants who learned information in a certain environment, such as underwater, demonstrated greater memory recall when tested in an identical environment.
- This lead to the hypothesis that attaching context to the objects being memorised, it served as a retrieval cue.
- Smith (1979) stated the keeping the internal state constant at the duration of encoding is adequate to serve as a retrieval cue, thus augment memory recall. Fisher & Craik (1977) denoted this effect as 'context reinstatement' when they corresponded retrieval cues with the manner in which information was memorised.
f. Transfer-Appropriate Processing
https://en.wikipedia.org/wiki/Transfer-appropriate_processing
- Morris et al. (1977) found this memory encoding strategy significantly improves memory retrieval by matching the processing type during encoding.
- They discovered an individual's memory recall is influenced by the performed tasks are identical during both the encoding and recall periods.
- One group was tasked with determining whether the new set of words rhymed with the target word, whilst the other group was tasked with determining the definitions of the target word and their new set of words. The 'rhyming' group demonstrated greater recall of words than in the 'definition' group.
- They hypothesised information encoding was more efficient in individuals instructed to focus on the rhyming aspect of the words. This is referred to as transfer-appropriate processing (TAP).
- TAP is a type of state-dependent memory that exhibits memory performance is dictated by not just the depth of processing, but also the relationship between the initially encoded information and its means of retrieval.
g. Encoding Specificity
- It refers to the context of learning influencing the encoding of newly learnt information.
- In 1979, Kanizsa showed 2 pictures in sequence to participants: the first one was a white vase with a black background, and the second one was 2 shadowy faces oriented towards one another with a white background.
- As a matter of fact, those 2 pictures were identical yet none of the participants admitted familiarity with the picture when shown for the second time. The researchers explained participants were expecting a vase in the first viewing, and then expecting 2 faces in the second viewing.
- This finding suggested the stimulus is interpreted within the context it is learned in.
https://en.wikipedia.org/wiki/Generation_effect
https://www.semanticscholar.org/paper/The-Generation-Effect-and-Memory-Rosner/25950779a6a87bf2a9e7184ad2469a2fbbdb7194
- McDaniel et al. (1988) theorised the generation effect may augment learning as individuals generate information or objects themselves instead of reading the content.
- Brown et al. (2014) pointed out that generation of information requires application of the generation effect, instead of passively choosing from information already available.
- In 1978, Slameka and Graf found participants tasked with filling in the blanks related to the list of words compared to the participants reading 2 lists of paired words demonstrated greater recall of word pairs.
What is the generation effect?
- It is a phenomenon that exhibits improved memory if one's mind generates the information rather than simply reads it.
- Scientists have uncovered the generation effect using a range of materials, such as word generation via the presentation of antonyms, synonyms, keywords in paragraphs, pictures, arithmetic problems, as well as free recall, cued recall, and recognition tests.
- For example, if I showed you a stimulus word "high", and the letter "s", what word would you generate in your mind?
- Short? Skyscraper? Stand? Silo?
What are the causes of the generation effect?
i. Lexical activation hypothesis
- This suggests a person explore their semantic memory during the word generation process by stimulating semantic aspects of their memory associated with the target item.
- Crutcher & Healy (1989) hypothesised the semantic features serve as retrieval cues and help improve the recall of the target item.
- Payne, Neel & Burns (1986) found subjects tasked with generating responses that rhymed with the target word and started with a presented letter were generating real words rather than non-words.
- The idea implies that people are more likely to engage in certain cognitive processes during the encoding stage when generating words rather than reading words.
- McNamara & Healy (2000) states that reinstating the procedures used for information encoding during the memory test produces the generation effect.
- de Winstanley & Bjork (2004) found an association between procedural account and transfer-appropriate processing, since both don't lead to the generation effect depending on encoding and retrieval mechanisms.
iii. Multi-factor transfer-appropriate processing account
- This idea describes the method of people focusing their processing on the type of information required to solve the generation task. The generation effect manifests when a subsequent test is sensitive to the same type of information.
- de Winstanley et al. (1996) found the generation effect doesn't transpire if there is a mismatch between the information processed to solve the generation task and the information required for an excellent performance on a subsequent memory test.
- Therefore, multi-factor transfer-appropriate processing account augments whole-list relational processing, which improves generation performance on a free recall test.
What are its limitations?
- If certain materials or instructions were altered, it would decrease the chance of or eliminate the generation effect from occurring. Therefore, there are claims there is no significant difference in memory improvements between repetitive reading and word generation of the same material.
- McDaniel et al. (1988) found the generation effect disappears when both groups are provided similar similar instructions of processing information.
- Lutz, Briggs & Cain (2003) stated that the generation effect has limited effectiveness in the context of new or unfamiliar material. This raises concerns about the usefulness of the generation effect in the classroom setting where students are learning new material.
- Mulligan (2004) hypothesised the generation effect may lead to a trade-off between the encoding of item information and associative information.
- Jurica & Shimamura (1999) argued encoding requires limited-capacity resources, thereby the encoding of other information is sacrificed for the desired encoding of a certain type of information.
i. Self-Reference Effect
https://en.wikipedia.org/wiki/Self-reference_effect
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3226761/
https://www.frontiersin.org/articles/10.3389/fpsyg.2016.01751/full
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Example stimuli: At encoding, objects are encoded 1/3 of the time by answering the question “is this an object you would buy some time in the next year?”, while participants must answer this question about their mother or Bill Clinton for the remaining two thirds. At recognition, participants indicated whether each item was the same as a studied item (same), similar to an item in encoding (similar), or new. |
- This effect refers to the tendency to encode information differently depending on the degree of implication. If one is asked to remember information in relation to themselves to a certain degree, they tend to demonstrate better recall.
- In 1955, George Kelly proposed a theory about the development of personal constructs within the human mind, which was inspired by the idea that each person's psychological processes are moderated by their anticipation of events.
- Jones (1971) suggested his 'attribution theory' in an attempt to explain the way how people attribute the cause of behaviours and events, which involves the formation of construct of self.
- The fundamental attribution error describes how an individual explains a person's given behaviour in a scenario by highlighting the internal characteristics e.g. personality rather than regarding the scenario's external factors.
- Jones et al. (1974) verified the idea that the self has a special construct by asking the subjects to describe their "most significant characteristics". The most common positive characteristics reported include "sensitive", "intelligent", and "friendly".
- This finding links to other cognitive phenomena such as illusory superiority, which involves individuals rating themselves differently in contrast to rating others.
- Klein (2012) found words encoded with respect to oneself (i.e. self-relevance effect) within the mind are recalled more frequently than words unrelated to the self.
- Nakao et al. (2012) found a negative correlation between altruism and the prevalence of the self-reference effect.
Which brain regions are involved?
https://www.frontiersin.org/articles/10.3389/fnhum.2015.00383/full
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Ventromedial prefrontal cortex (VMPFC), posterior cingulate cortex (PCC), bilateral angular gyrus (AG) |
- A quantitative meta-analysis by Qin & Northoff (2011) found a number of cortical midline structures were involved in the concept of self.
- It suggested these neural structures are activated during tasks that associate with the social or psychological aspects of the self, such as self-preferential judgmeents, self-appraisal, and judgments of personality traits, as well as the processing of social relationships and recognition of others that are familiar to oneself.
- Uddin et al. (2007) demonstrated the midline areas are activated when one is understanding social interactions between others or attributes social traits to others (i.e. impression formation).
ii. Prefrontal cortex (PFC)
- Researchers observed the medial PFC to be involved in the self-reference effect.
- The PFC plays a fundamental role in planning of complex behaviour and the expression and regulation of personality characteristics in social situations.
- Gillihan et al. (2005) conjectured the medical PFC in both hemispheres to be involved in forming the "self model", which is a theoretical construct comprised of fundamental aspects such as experience of agency and feelings of continuity and unity.
- Experimental findings revealed the ventromedial PFC was activated during tasks concerning one's own personalities or preferences, the adoption of a first person perspective, or the reflection of own affective state.
- fMRI studies found the ventromedial and dorsomedial PFC are highly activated during self-referential tasks, indicated by stronger blood-oxygen-level dependent (BOLD) signals.
iii. Parietal lobe
- A fMRI study by Sajonz et al. (2010) found the medial and lateral parietal cortex were highly active when subjects performed self-referential tasks.
- A transcranial magnetic stimulation (TMS) study by Northoff et al. (2006) found the parietal lobe plays a role in the retrieval of previous judgements of mental self during the comparison of judgement of others.
How does this effect develop over the lifetime?
a. Childhood
- Part of the children's development includes the sense of self and their understanding of the world around them.
- Sui & Ying (2005) observed the self-reference effect occurring in children as young as 5 years old based on their recall abilities. Furthermore, they found young children developed the ability of verbal learning to enhance their memory, augmenting their language development.
- Rose et al. (2011) found preschoolers (3 year old children) demonstrated self-referencing capabilities in their temporal memory.
b. Adulthood
- Heatherton et al. (2006) found subjects self-referencing with an intimate person, such as family member, friend or spouse, affected their memory advantage. However, an adult's capacity to self-reference is relatively firm throughout their lifespan.
- Gutchess et al. (2007) stated that memory performance in ageing adults can be improved by employing a number of memory strategies and orientations that utilises "deep" encoding processes. e.g. Mnemonics
- However, researchers pointed out differences between the older adults and younger adults regarding on their use of the self-reference advantages. Although older adults demonstrate excellent recognition of self-referenced items, the benefits they reap from this advantage is influenced by the amount of cognitive resources.
- Although the self-reference effect can improve an older adult's memory, its benefits are limited regardless of the social and personally relevant essence of the task. Researchers implied this is due to changes in brain activation associated with ageing.
- Studies found the medial PFC and the cingulate gyrus are more activated in older adults than younger adults in self-referential processing, which indicated the older adults have a boosted tendency to process positive information relative to themselves.
- Kensinger & Schacter (2008) conjectured that this "positivity shift" occurs in older adults due to increased focus on emotion regulation goals compared to younger adults, as well as higher motivation to obtain emotional meaning from life and conserve positive affect.
What does this effect have on students?
- Rogers, Kuiper and Kirker (1977) found students visualised their own versions of 'self' as a schema that processes personal information, interpretation, and memories.
- Gutchess, Kensinger, and Schacter (2007) found older adults demonstrated superior abilities in recognising self-referenced items relative to them compared to younger people. An interesting finding was availability of cognitive resources lead to a divergence from social and emotional processing in both young and old adults.
- Hartlep & Forsyth (2001) found memory retrieval was improved with more elaborative cognitive frameworks, which indicates the considerable level of knowledge of themselves. They suggested that recall of studied material can be enhanced by elaborating it to their pre-existing knowledge or relating it to personal experiences.
- Serbun, Shih & Gutchess (2011) found the self-reference effect improved the specificity, level of detail, and accuracy of memory, as well as details of a past event.
- Nakao et al. (2012) found the self-reference effect was associated with low altruism since both effects are exhibited by the medial prefrontal cortex (mPFC). Since high altruism is related to social desirability, it correlates with a number of memory enhancement effects that varies depending on individual past experiences.
How did the self-reference effect evolve?
- Cunningham et al. (2013) proposed an association between the self-reference effect and human survival as part of an evolutionary mechanism, since it improved the memory of encoded material useful for survival.
- Nairne et al. (2007) stated an enhanced ability to recall past events may have assisted our ancestors solve complex problems that concerned their own survival.
- Weinstein et al. (2008) asserted that humans tend to encode and retrieve more information related to survival compared to information unrelated to survival.
List of examples
- Individuals tend to attribute someone else's behaviour to their deposition, and to attribute their own behaviour to the situation. This is known as the 'fundamental attribution error'.
- One tends to demonstrate better recall when tasked to remember words relating to yourself, rather than receiving other instructions.
- Processing and formation of neural connections within the mind increases in relation to the topic related to the self.
- In marketing, Asian consumers self-referenced Asian models in advertising more than Caucasian consumers. Furthermore, Martin et al. (2004) found Asian models who advertised products that were usually endorsed by Asian models lead to increased self-referencing from consumers.
- Individuals are more likely to remember birthdays that are nearer to their own birthdays than more distant birthdays. e.g. I'm more likely to remember birthdays in October, November & December compared to May, June and July.
- Martin et al. (2007) found female consumers engage in self-referencing when they observe female models in different body shapes in advertising. Women who believed they can control their weight respond more positively to slimmer models in advertising, which is moderated by self-referencing.
j. Salience
https://en.wikipedia.org/wiki/Salience_(neuroscience)
https://www.researchgate.net/figure/Encoding-salience-in-space-and-timea-Salience-encoding-in-monkey-parietal-cortex73_fig3_10964524
Also known as saliency, it refers to item's state or quality that stands out from its counterparts.
For example:
88888888888888888888889888888
Do you spot the odd number out?
Which brain regions are involved in salience?
https://www.researchgate.net/figure/Saliency-maps-of-language-motor-and-working-memory-tasks-A-The-story-and-math_fig1_340932943
These are saliency maps of language, motor and working memory tasks, which were estimated by using the guided backpropagation based on the pre-trained single-domain GCN annotation models that only used fMRI signals from the corresponding. (A) The story and math conditions demonstrated high salience in the primary auditory cortex and perisylvian language-related brain regions. (B) Different types of movements were associated with salient features in the motor and somatosensory cortex. (C) The 0-back working memory task mostly activated the ventral visual stream for encoding different types of images.
- Scientists found the hippocampus uses previous memories to filter new incoming stimuli in the assessment of salience and context, and transfers the most important information into long term memory via the entorhinal cortex.
- Snow et al. (2009) found the pulvinar nuclei (in the thalamus) regulates physical / perception salience in attention selection.
- Baliki et al. (2013) stated D1-type medium spiny neurons within the nucleus accumbens shell (NAcc shell) allocates appetitive motivational salience ("want" and "desire"), or 'incentive salience', with rewarding stimuli. On the contrary, D2-type medium spiny neurons within the NAcc shell allocates aversive motivational salience to aversive stimuli.
- Li (2002) found the primary visual cortex (V1) produces a bottom-up saliency map from visual inputs to guide reflexive attentional shifts or gaze shifts.
- Yan, Zhaoping & Li (2018) reported the saliency of the location correlates the responses of the V1 neurons to that location relative to V1 neurons' responses to other visual locations.
- Zhaoping (2014) explained that salience occurs when a red item is present among green items, which stimulated increased V1 responses and directs attention or gaze to that object.
- Zhaoping (2018) also found the V1 neural responses are transmitted to the superior colliculus to guide gaze shifts to the salient locations. Furthermore, it was discovered that the location of an eye-of-origin single object in visual engages attention or gaze, e.g. a horizontal bar displayed to the left eye in a background of many vertical bars displayed to the right eye.
What is salience bias?
- Also known as perceptual salience, it is the cognitive bias that predisposes individuals to focus on items that are more conspicuous or emotionally salient and ignore anything commonplace. It is closely associated with the concept of availability in behavioural economics.
- In his 2008 book Nudge: Improving Decisions about Health, Wealth, and Happiness, Richard H. Thaler described how availability is closely associated with accessibility and salience. Furthermore, he thought vivid and easily imagined causes of death, such as earthquakes, often inflate people's estimates of probability, and boring causes of death, e.g. asthma attacks, deflate people's estimates of probability even if statistics demonstrate the contrary.
- Moreover, he mentioned the timing of such events can influence its salience in our minds, e.g. more recent events tend to have a significant impact on our behaviour, and on our fears, than earlier events.
How is salience linked to schizophrenia?
- In 2005, Kapur postulated that an aberrant assignment of salience to the aspects of one's own experience is triggered by a state of elevated dopamine levels.
- Lee et al. (2015) described the relationship between the aberrant salience anomalies and the modulations of activity in the mesolimbic system, which contains brain regions such as the striatum, amygdala, hippocampus, and the parahippocampus gyrus.
- Berridge et al. (1998) found dopamine regulates the conversion of neutral information of the external stimulus into an aversive entity, creating a salient event.
- Kapur (2003) reported the symptoms of schizophrenia may manifest from the "aberrant assignment of salience to external objects and internal representations". Moreover, antipsychotic medications were found to decrease positive symptoms by diminishing aberrant motivational salience by blocking dopamine D2 receptors.
Describe the model of visual saliency
- Frintop et al. (2010) attempted to model the mechanism of human affection, especially the bottom-up attentional mechanism, which includes both spatial and temporal attention. This process is known as visual saliency detection.
(1) Based on the spatial contract analysis, a centre-surround mechanism is utilised to describe saliency across certain scales, brought about by the putative neural mechanism.
(2) Based on the frequency domain analysis, this model uses the phrase spectrum to assign saliency to occasional magnitudes.
- Itti et al. (1998) pointed out a key limitation is that computational complexity results in decreased real-time performance, even on modern computer hardware.
- Achler (2013) postulated that saliency and associated speed-accuracy phenomena may be an integral mechanism activated during recognition through the gradient descent.
k. Retrieval Practice
- One effective tool that augments encoding during learning is a practice test. Known as the 'testing effect', it involves generating and regenerating the material being learned, which in turn increases one's exposure to the material.
- Karpicke (2012) thought these practice tests augment the processing of information deeply compared to repetitively reading the material or a pre-made test.
- Roediger & Karpicke (2006) found subjects tasked with an immediate recall test after reading a passage demonstrated greater recall compared to subjects instructed to reread the passage. This suggested retrieval practice is a practical tool to encode information into long-term memory.
2. How is memory stored in the brain?
https://en.wikipedia.org/wiki/Storage_(memory)https://qbi.uq.edu.au/brain-basics/memory/where-are-memories-stored
https://dornsife.usc.edu/news/stories/3617/where-are-memories-stored-in-the-brain-new-research-suggests-the/
Memory storage refers to the process of storing newly encoded information into short-term memory. I'll discuss short-term memory and long-term memory in detail later on.
What models of memory storage were proposed?
https://www.researchgate.net/figure/Two-theories-of-time-dependent-memory-reorganization-A-The-standard-consolidation_fig1_228358010
- Proposed by Hooke (1969) and Semon (1923), this model implies that encoded memories translate into a vector of values, with each scalar value of a vector representing a unique aspect of the item being encoded.
- They thought a single memory segments into numerous features, with each feature representing one aspect of the encoded memory.
- The corresponding vector is subsequently included into the pre-existing or developing matrix, comprised of multiple traces or vectors of memory.
- In order to recall a specific memory, the matrix needs to probed with a certain cue, which helps evaluate the similarity between the test vector and the existing vectors stored in the memory matrix.
- In addition, the model suggests the recall process requires a thorough parallel search between every existing trace within the evolving matrix, which would demand immense neurological computing power within a short period of time.
- 2 key limitations were identified with this model: (1) the concept of an evolving matrix in human memory seems implausible, and (2) computational searches for similarity against an enormous storage base of traces within the memory matrix to evaluate similarity is beyond the human brain's capabilities.
https://en.wikipedia.org/wiki/Hopfield_network
https://www.kdnuggets.com/2018/02/8-neural-network-architectures-machine-learning-researchers-need-learn.html/2
- This model attempts to overcome the limitations of the multi-trace distributed memory model.
- It conjectures that neurons in a neural network create a complex network with other neurons, which manifests in a complicated interconnected network. It characterises each neuron by its individual activation value, and the connection between 2 neurons is distinguished by the weight value.
- The McCulloch-Pitts dynamical rule determines the interaction between 2 neurons, while the Hebbian learning rule characterises the change of weight and connections between neurons influenced by learning.
- Anderson (1970) demonstrated that amalgamating the Hebbian learning rule and McCulloch-Pitts dynamical rule enables the network's generation of a weight matrix capable of storing connections between a range of memory patterns.
- In 1982, John Hopfield designed a recurrent artificial neural network called a Hopfield network. However it was first described by Little in 1974 derived from Ernst Ising's work with Wilhelm Lenz. Thus it is also given other names such as Ising model of a neural network, or Ising-Lenz-Little model.
- Hopfield networks function as content-addressable or associative memory systems with binary threshold nodes.
https://www.semanticscholar.org/paper/The-Search-of-Associative-Memory-with-Recovery-(-)-Huber/711c33861ca68e37fcf467327391eda3ab4a2fd6
- Known as SAM or search of associative memory model, the dual-store memory search model is one of the most advanced computational models of memory.
- This model was first proposed by Atkinson and Shiffrin in 1968, and later improved by other researchers, including Reejimakers and Shiffrin.
- It utilises both short-term store (STS) and long-term store (LTS) / episodic matrix i.e. short-term memory and long-term memory respectively.
- According to the model, a newly encoded item is initially transferred to the STS and remains there. Meanwhile, vector representations undergo different types of associations in the LTS, which include autoassociation, self-association, hetereoassociation (inter-term association), and context association (i.e. association between the perceived item and encoded context).
- There is a direct correction between the item's residual item in the STS and the degree of association with itself and its encoded context.
- When 2 items are contiguous within the STS, their associative strength is consolidated and tend to be recalled more frequently from LTS.
- It is thought the first set of items have a higher chance of being recalled in the STS, whereas older items have a higher chance of being forgotten, hence leave the STS.
- The regency effect of the recall trials described how the last items of a list seemed to be recalled more accurately over other items since they were the most recent items stored in short-term memory.
- If a distractor is introduced during the recall period, those last items of the list may be easily forgotten as an insufficient amount of time has elapsed to develop any meaningful association within the LTS.
3. How does one recall memories?
https://en.wikipedia.org/wiki/Recall_(memory)https://www.frontiersin.org/articles/10.3389/fpsyg.2015.01907/full
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2658622/
- Memory recall refers to the mental process of retrieving information stored in memory.
- The first studies into memory recall were conducted by Hermann Ebbinghaus in 1885, with Ebbinghaus being the test subject. He memorised nonsense syllables and tested his recall of those words over varying periods of time.
- He evaluated that his memory loss occurred rapidly over the first several hours or days, however it steadied gradually over subsequent days, weeks, and months. His findings included retention of information associated with multiple learning, over-learning and spaced out study periods.
What are the theories of memory recall?
i. Two-stage theory
- This theory implies memory recall initiates with a search and retrieval process, followed by a decision or recognition process where the correct information is selected from retrieved memories.
- To account for the superiority of the recognition process over recall, it states recognition is only involved in the recognition process.
- Watkins & Gardner (1979) pointed out that recognition involves 1 process (where errors may occur), whereas recall involves 2 processes.
- Tulving & Thomson (1973) discovered that in cases where words aren't recognised but able to be recalled, the recall process is more superior than recognition.
ii. Encoding specificity
- This theory analyses similarities between the processes of recognition and of recall. It states that memory selects information from the memory trace, or the circumstance in which it was learned, and from the environment in which it was retrieved.
- Tulving & Thomson (1973) stated that encoding specificity takes context cues into account since it fixates on the retrieval environment, as well as the fact that recall may be superior to recognition.
What are the different types of memory recall?
Khan Academy:
https://www.youtube.com/watch?v=Uhyk2bRTguI&ab_channel=khanacademymedicine
CVLT Trial B:
https://www.youtube.com/watch?v=opKTTyWCXSU&ab_channel=VictoriaMartinez
1. Free Recall
https://en.wikipedia.org/wiki/Free_recall
- It describes the activity of recalling a list of items in any order after a period of memorisation. Studies found evidence of primacy and recency effects in free recall trials.
- Can you recall the word list I asked you to memorise, in any order?
- If you did try to do this free recall test without scrolling up, you'll likely remember the 1st 3 words and the last 3 words of that list. Those are the primacy and recency effects, respectively.
- This involves participants given cues to recall a word list they are tasked to remember. Cues include the first letter of the list words, the word's definition, a synonym, a visual image or an auditory clue.
- Let’s try to recall the list of words again. Here are some cues to guide you: Phone, Rail, Backpacker, Trunk, Zucchini, Bow, Wood, Dwarf, Fish
https://www.sciencedirect.com/topics/psychology/serial-recall
- It refers to the ability to recall items or events in the order of occurrence. It helps humans and primates to remember the order of events in our lives, i.e. autobiographical memories.
- Can you recall the aforementioned word list in order from left to right?
- Here’s a hard serial recall task: Can you remember when these sporting tournaments occurred in order throughout the calendar year?
-- Masters Tournament, PGA Championship, United States Open Championship, The Open Championship (The British Open)
So far, 8 different effects were observed in serial recall studies:
i. List length effect
= Serial recall ability diminishes as the length of the list or sequence increases
ii. Primacy and recency effects
= Primacy effects cites greater recall of items earlier in the sequence, whereas recency effects cites greater recall of the last few items.
iii. Transposition gradients
= This refers to greater recall of an item being recognised rather than a sequence of items.
iv. Item confusion errors
= An incorrectly recalled item associates with the tendency to respond with an item that resembles the original item in that position.
v. Repetition errors
= They occur when a person repeats an item from a previous position in the sequence in another position.
vi. Fill-in effects
= This refers to the tendency for the next item recalled to be the item that was displaced by the error. e.g. Original sequence ABCD and recall is ABD then C.
vii. Protrusion effects
= This refers to items from a previous list being accidentally recalled on a new list.
viii. Word-length effects
= Avons et al. (1994) found shorter words are recalled more accurately than longer words.
4. Recognition
https://en.wikipedia.org/wiki/Recognition_memoryhttps://www.sciencedirect.com/topics/agricultural-and-biological-sciences/recognition-memory
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2323975/
https://www.frontiersin.org/articles/10.3389/fpsyg.2013.00787/full
Imagine you are sitting on a crowded train. You look in front of you and notice a person. Immediately, you sense a form of familiarity regarding this person in terms of appearance, fashion sense and voice profile, but you struggle remember their name. As you attempt to recall the identity of this person, you start to retrieve specific details about your previous encounter. For instance, you may recall this person at a networking event held at a bar a month ago and they wore jeans, a pair of rectangular spectacles and a cardigan. This process you experience is called "recollection".
What is recognition memory?
- Recognition is defined as the ability to recognise previously encountered events, objects, or people.
- When you re-experience a previous event, it matches with neural representations stored in your long-term memory, triggering matching signals.
- The first mentions of recognition in psychology were by Wilhelm Wundt, who he first conceptualised as "know-againness" or "assimilation" of a former memory image to new image in the 19th century.
- In the late 19th century, English Doctor Arthur Wigan was the first to describe recognition in his book Duality of the Mind. He hypothesised the feelings of familiarity were stimulated by the brain's assumed function as a double organ.
- In 1896, Arthur Allin was the first person to publicise a report that attempts to explicitly define and distinguish between subjective and objective definitions of the experience of recognition.
- Woodsworth (1913) and Margaret and Edward Strong (1916) were the first scientists to conduct experiments on recognition by using the delayed matching to sample task in an attempt to understand recognition memory.
- In 1969, Benton Underwood was the first person to analyse the concept of recognition errors in the context of language. He found recognition errors arise from words with similar attributes.
- In 1980, George Mandler proposed the recollection-familiarity distinction, which is formally known as the dual-process theory.
What is the dual-process theory?
- Curran et al. (2006) explained the reasons for controversy regarding the dual-process theory vs. single-process theory debate was due to the difficult of collecting separate empirical estimates of recollection and familiarity, as well as the penuriousness of single-process theory.
- Rutishauser et al. (2008) found hippocampal neurons were activated in response to familiar objects, regardless of successful recollection, which supported the single-process theory. However there is ambiguity regarding the specificity of neural responses linked to successful item recognition or conscious recollection.
- Hannula & Ranganath (2009) used object-scene associative recognition to demonstrate no link between the activation of the hippocampus only and successful associative recollection, unless the prefrontal cortex was also activated. Nevertheless, there is evidence that the hippocampus is associated with recovery of relational information, since it requires concomitant activation with the prefrontal cortex for conscious recollection.
- On the other side of the debate, studies on amnesics found patients with selective damage to the hippocampus demonstrated impairment only in recollection but not in familiarity, which supports the dual-process model.
- Bowles et al. (2010) reported patient N.B., who only had her hippocampus and parahippocampal cortex, demonstrated impaired familiarity but faultless recollection processes relative to controls in a yes-no recognition paradigm.
- A study Squire et al. (2007) concluded that the hippocampus and parahippocampal regions are cogs in a unitary memory strength system, when performance was matched post-hoc.
- Mandler (2008) suggested the dual process theory explains how humans are able to distinguish two types of recognition: (1) recognising of the fact they encountered some object/event before, and (2) recognition of the specific object/event. e.g. Whether we initially recognise a person's face, then subsequently recall whose face it was.
- Studies in the 1970s suggested this delayed recognition phenomenon demonstrated differences between fast familiarity and slow recollection processes, which indicated the "familiarity" system contains two functional subsystems to perform recognition memory. Firstly, the recognition of previously presented stimuli and, secondly, the system determines recognition of objects as novel.
- So far, there is no definitive answer to the dual-process vs single-process model of recognition memory debate. More neuroscientific research is required to settle this controversy.
What are the factors of recognition?
i. Decision Making
- Bernbach (1967) stated a comparison between available information and some guiding internal criteria is required to consider the most advantageous decision.
- In order to estimate the effect of internal criteria or biases, signal detection theory is applied to recognition memory. In support for the dual process model, Yonelinas (2001) assumed recognition memory exhibits a signal detection process in which old and new items each have a distinct distribution along a dimension.
- William Banks (1970) assumed percentage correct scores may be biased indicators retention, thus recommended SDT techniques to be applied where possible to distinguish the truly retention-based aspects of memory performance from the decision aspects.
- There are 2 types of test items, "old" (meaning it did appear in the list) and "new" (meaning it didn't appear in the list). There is an assumption that the subject compares the trace strength of the test item with a criterion, responding "yes" if the strength exceeds the criterion and "no"otherwise.
- Norman & Wckelgren (1969) stated the strength theory assumes noise in the value of the trace strength, the location of the criterion, or both, thus they assumed this noise is normally distributed.
- Hinrichs (1970) assumed the item's strength decreases monotonically as a continuous function of time or number of intervening items.
- Bernbach (1967) defined false hits as 'new' words incorrectly recognised as old, and a majority of them indicates a liberal bias. In addition, misses are defined as 'old' words mistakenly not recognised as old, and a majority of them indicates a conservative bias.
- Parks (1966) insinuated the relative distributions of false hits and misses can be analysed to interpret recognition task performance and correct guesses. This means an above-threshold response is a result of correctly remembering only target items since they appeared on the list. A below-threshold response is a result of lures or forgotten targets, which doesn't produce any memory signal.
- John Wixted (2007) interpreted the memory-free guesses due to lures as false alarms to the dual process model.
ii. Level of processing
- Adams (1967) implied the level of cognitive processing applied on a given stimuli has an effect on recognition memory performance, which means elaborate, associative processing improves memory performance. e.g. Semantic associations improved recognition performance more than feature associations.
- Hunt & Einstein (1981) found lower-depth item-specific processing (e.g. interpreting the item's enjoyment) is used to distinguish interrelated items, which improves recognition memory performance over relational processing.
- Roediger & Guynn (1996) found additional related processing improves recognition performance, but not by a task that duplicates the automated processing already executed on the list of items.
- Thomson & Tulving (1970) defined encoding specificity as the enhanced effect of testing conditions matching learning conditions on memory performance.
- Features during the learning period including the environment, current physical state, or mood, can be encoded in a person's memory trace. Later in the retrieval stage, any of these features can act as cues to assist in recognition.
- e.g. Godden & Baddeley (1975) conducted a memory study on scuba divers and found divers that learned in the water demonstrated better test results compared to divers that learned on land. This supports the theory that memory performance improves when retrieval conditions match encoding conditions.
- State-dependent learning refers to the effect of an individual's physical state on their memory performance.
- Bower (1981) defined 'moon congruent memory' as enhanced memory performance due to matching of the emotional content of the stimuli with the prevailing mood.
- The presence of other individuals can affect memory recognition, known as collaborative inhibition and collaborative facilitation, which decrease and increase memory performance on recall tasks in groups respectively. It suggests the activation of a specific memory trace is required for memory recall, and any outside thoughts could interfere with the memory trace.
- Hinsz (1990) pointed out that recognition isn't affected by external interference because it doesn't use the same retrieval plan as memory recall.
iv. Recognition errors
- The 2 categories of recognition memory errors are false hits / false alarms (i.e. identifying a new event as old) and misses (i.e. failure to identify a previous event as old).
-- Feature error: Parts of an old stimulus is presented in combination with a new stimulus.
e.g. Original list = Sidetrack, Monogamous, Foregone
Test list = Sidestep, Monopoly, Forfeit
-- Conjunction error: Parts of multiple old stimuli are combined
e.g. Original list = Landmark, Backwards, Foreground, Waterscape
Test list = Background, Forwards, Landscape, Watermark
- Jones et al. (2001) found both types of errors can be triggered by both auditory and visual modalities, which indicates the processes that cause these errors aren't specific to a particularly modality.
- Roediger & McDermott (1995) found a 3rd false hit error that can be a result of the Deese–Roediger–McDermott paradigm. Nadel & Payne (2002) explained that a list of words associated with one word not on the list would likely induce the subject to recognise that word as 'old' in the trial.
- e.g. Original list = Main, supreme, integral, essential, crucial, paramount
v. Mirror effect
- Robert Green (1996) stated the mirror effect is induced by stimuli that tend to be recognised as old when old stimuli also tend to be recognised as new when they are new in memory recognition.
- In other words, it refers to stimuli that are easier to remember when you have previously studied it (i.e. old) and easier to reject to when you haven't encountered it before (i.e. new).
- Glanzer & Adams (1985) found the mirror effect can be applied in tests of associative recognition, measures of latency responses, or discriminations of order.
Which brain structures are involved in recognition?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2323975/
https://www.researchgate.net/figure/Regions-involved-in-episodic-memory-a-Brain-areas-important-for-human-episodic-memory_fig1_46403860
a. Normal brain
-- The visual ventral stream
The visual word form area in the left fusiform gyrus associates with word recognition. Similarly, the fusiform face area in the right hemisphere associates with facial recognition.
-- Medial temporal lobe
In the temporal cortex, the medial region associates with recollection whereas the anterior region associates with familiarity.
-- Frontal lobe
- There is evidence that the prefrontal cortex associates with recollection whereas the right prefrontal cortex associates with familiarity.
- Ranganath et al. (2000) found both non-verbal and verbal stimuli stimulated the left prefrontal cortex during recollection tasks, which suggests it is associated with detailed remembering.
- The lateral areas are associated with recollection whereas the superior areas are associated with familiarity.
- In the medial parietal region, the posterior cingulate area associates with recollection, whereas the precuneus area associates with familiarity.
This region is linked to recollection whereas familiarity depends heavily on the surrounding medial-temporal regions, especially the perirhinal cortex.
-- Encoding
A number of questions regarding the encoding of recognition memory include:
- How one can retrieve a particular item or object through memory?
- Is the retrieved item a function of recollection judgement (remembered) or a familiarity judgement (simply known)?
Factors that influence the strength of recognition memory include:
- Level of attention when memorising the information
- Any distractions
- Active or passive attempt to learn
- Prior rehearsal of the information or not
Studies found a higher level of bilateral activation in the prefrontal cortex, hippocampus, and parahippocampal gyrus associated with higher attention, hence greater formation of detailed, recollective memories. Furthermore, in the presence of distractions during the memory-encoding process, only the right prefrontal cortex and left parahippocampal gyrus were activated, which suggested these regions are linked to familiarity.
-- Audition
Auditory recognition memory is associated with the medial temporal lobe, specifically the perinhinal and entorhinal cortices. More research is required to understand the hippocampus's role in auditory recognition memory inside human brains compared to other animals' brains such as dogs.
-- Olfaction
In rodents, olfactory recognition memory is associated with the orbitofrontal cortex (OF), an area that is reciprocally linked with the perirhinal and entorhinal areas of the medial temporal lobe. Furthermore, Schaefer et al. (2002) found individual body odours were represented at the major histocompatibility complex (MHC).
-- Gustation
Gustatory recognition memory is associated with the anterior temporal lobe (ATL) in humans. Gutierruz (2004) found taste recognition memory and conditioned taste aversion in humans are linked to cholinergic transmission in the perirhinal cortex.
-- Tactition
Suzuki et al. (1993) found tactual recognition memory in monkeys is associated with the perirhinal and parahippocampal cortices. However, more research is required to understand whether this form of recognition memory is linked with other brain regions.
b. Lesioned brain
Damage to the fusiform face area (FFA) leads to prosopagnosia, the inability to recognise faces. Lesions to various brain regions such as FFA act as case study data to aid researchers in understanding the neural correlates of recognition.
-- Medial temporal lobe
- Damage to the hippocampus results in severe retrograde or anterograde amnesia, the ability to recall certain events from their past or create new memories respectively.
- Amnesics have normal short-term memory, but exhibit reduced long-term memory due to impairment in memory consolidation in the hippocampus.
- People with anterograde amnesia can't remember learning any procedural skills, however their ability to perform procedural skills match that of a neurotypical person.
- Damage to the temporal lobes also results in visual agnosia, an inability to properly recognise objects either due to a perceptive deficit, or a deficit in semantic memory.
- People with visual agnosia may identify features of an object (e.g. size, shape, edges, etc.), but they can't recognise and name the object. This phenomenon is known as integrative agnosia.
-- Parietal lobe
- Damage to the right posterior parietal lobe results in an inability to recognise objects using a variety of visual stimuli, such as colours, familiar objects, and new shapes. However, an accurate performance on recall tasks indicates the encoding process has been spared.
- Damage to the lateral parietal cortex (either dextral or sinistral) impairs recognition memory, but spares source memories. This finding suggests the lateral parietal cortex is linked to the conscious experience of memory.
- The attention to memory (AtoM) model hypothesises the posterior parietal lobe shares fundamental roles in both memory and attention, i.e. regulating top-down versus bottom-up processes. It states that the superior parietal lobe maintains top-down (deliberate) goals provided by explicit directions, whereas the inferior parietal lobe stimulates the superior parietal lobe to redirect attention to bottom-up driven memory in responses to an environmental cue.
- Simons et al. (2009) explained that the hypothesis accounted for episodic memory, but failed to account for the fact that reducing the the top-down memory cues provided to patients with bilateral posterior parietal lobe damage did not elicit a significant effect on memory performance.
- The output-buffer hypothesis suggests the parietal cortex stores the qualitative content of memories ready to be retrieved, and allow them to be accessed for decision-making processes. This means parietal lobe lesion patients should demonstrate decreased confidence in recognition judgments.
- Cabeza et al. (2001) proposed the mnemonic-accumulator hypothesis that posits the parietal lobe emits a memory strength signal that compares with internal criteria to conduct old/new recognition judgments. This associates with signal-detection theory, and perceives recollected items as 'older' than familiar items.
- The attention-to-internal representation hypothesis suggests that parietal regions adjust and maintain attention to memory representations, which assocaites with the AtoM model.
- Wagner et al. (2005) discovered the parietal lobe is activated during recognition tasks featuring old stimuli compared to novel stimuli. Furthermore, the ventral region was highly activated for recollected stimuli, and the dorsal region was highly activated for familiar stimuli.
- The lateral region of the parietal cortex is known to communicate with areas of the medal temporal lobe, including its hippocampal, parahippocampal, and entorhinal regions. It suggests these neural connections encourages the medial temporal lobe to play a role in cortical information processing.
-- Frontal lobe
- Schacter & Dodson (2001) discovered lesions in the right frontal lobe lead to false recognition errors, which is thought to be caused by a variety of factors such as defective monitoring, retrieval and decision processes.
- Rapcsak et al. (2001) found lesions in the frontal lobe resulted in anterograde and relatively mild retrograde face memory impairment.
How did recognition memory evolve in the brain?
- Our ability to recognise new or old stimuli provided a number of evolutionary advantages, such as rapid identification of threats in jeopardising environments and appropriate responses to such threats.
- The perirhinal cortex is linked to both the fear response and recognition memory, which activates upon recognition of new stimuli as opposed to stimuli it's already familiar with. The hippocampus first identifies the stimuli via the perirhinal cortex, where it autonomously and swiftly appraises the stimuli's familiarity and the recency of its perception.
How is recognition measured?
i. Old-new recognition
This is an example of an old-new recognition test.
Source: Neural Univariate Activity and and Multivariate Pattern in the Posterior Superior Temporal Sulcus Differentially Encode Facial Expression and Identity. Yang et al. (2016)
https://www.researchgate.net/figure/Example-stimuli-of-the-old-new-face-and-flower-recognition-task-Participants-firstly_fig3_299342422
ii. Forced choice recognition
This is an example of a forced choice recognition.
SET = Stimulus Exposure Time
TET = Target Exposure Time
FET = Feedback Exposure Time
Source: A Bayesian latent group analysis for detecting poor effort in a sample of cognitively impaired patients. Ortega, Piefke & Markowitsch (2014)
https://www.researchgate.net/figure/Visual-recognition-forced-choice-task-SET-stimulus-exposure-time-TET-target_fig1_262940435
- In this task, subjects were asked to identify the correct item from a selection of 2 to 4 items. The correct item is the target (previously presented) item, while the others are similar that act as distractors.
- Radvansky (2006) stated experimenters can manipulate and control item similarity or item resemblance. This theoretically improves understanding memory retrieval, and conceptualise the type of existing knowledge utilised to determine their choice based on memory.
iii. Mental chronometry
- In terms of recorded response time, a quicker time demonstrates a simpler process, whereas a slower time demonstrates a complex physiological process.
- Hermann von Helmholtz was the first psychologist to investigate the measurability of the velocity of a nerve impulse.
iv. Dual process models
This is a model for diagnostic reason based on dual-process theory.
Source: Cognitive biases associated with medical decisions: a systematic review
https://www.researchgate.net/figure/A-model-for-diagnostic-reasoning-based-on-dual-process-theory-from-Ely-et-al-with_fig6_309765658
- Atkinson & Juola (1973) first presented the earliest model of dual process theories, which suggested the familiarity process is first activated as a rapid search for recognition. Unsuccessful attempts at memory trace retrieval would result in a self-conscious search into the long-term memory storage.
- Mandler (1980) proposed his version of dual process theories, which suggested that the processes of familiarity and recollection occur simultaneously. Nevertheless, the familiarity process finishes the search before the recollection process.
Where is recognition memory applied?
- One common application of recognition memory is academic exams featuring multiple choice tests.
- The University of Waterloo (2008) stated a "good" academic test didn't require the use of recognition memory, but rather assesses the level of encoding and concept recall in an individual.
- They expounded that heavy reliance on recognition based on familiarity in a memory test may lead to an incorrect answer.
Which brain regions are involved in memory recall?
http://www.ajnr.org/content/36/5/846
https://www.cell.com/trends/cognitive-sciences/fulltext/S1364-6613(19)30235-9
- Studies have identified the brain regions involved during recall include anterior cingulate cortex, globus pallidus, thalamus, and cerebellum, which are part of the cerebello-frontal pathway.
- PET studies on recall and recognition discovered elevated regional cerebral blood flow (RCBF) in the following brain regions:
-- Hippocampal and parahippocampal regions of the medial temporal lobe
-- Anterior cingulate cortex,
-- Posterior midline area including the posterior cingulate, retrosplenial region, precuenus, and cuneus region
-- Inferior parietal cortex (particularly right hemisphere)
-- Cerebellum (particularly left)
The specific role of each of the 6 main brain regions in episodic retrieval is still ambiguous, but researchers have proposed a few theories.
-- Right prefrontal cortex: Retrieval attempt
-- Medial temporal lobes: Conscious recollection
-- Anterior cingulate: Response selection
-- Posterior midline region: Imagery
-- Inferior parietal: Awareness of space
-- Cerebellum: Self-initiated retrieval
- Paller & Wagner (2002) measured differences in the evoked potentials and haemodynamic activity between subsequent recall and non-recall. This phenomenon is known as the subsequent memory effect (SME).
- Fernandez et al. (1999) demonstrated the SME exhibits both as a negative deflection in the rhinal cortex of an event-related potential (ERP) 400 ms after exposure to a stimulus, and as a positive hippocampal ERP 800 ms after stimulus onset.
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| Medial surface of left cerebral hemisphere |
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| Inferior parietal lobule highlighted in yellow |
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| Left and right cerebellum highlighted in red |
1. Attention
- Craik et al. (2000) found attention influences memory formation during the encoding phase. If a subject performs a distractor task, it disrupts proper information input and decreases the amount of information learned, hence reduces retrieval success.
- Gotch (2012) stated individuals have greater recall of negative and positive vocabulary than neutral vocabulary since they don't spark emotion.
- When the speaker's voice is accentuated with sadness, contentment or frustration, or the speaker communicates close to the heart, people tend to pay more attention.
- Furthermore, emotional vocabulary and sounds were more memorable than the neutral equivalent given the test location and sound speakers were identical.
- If you hear words spoken calmly and neutrally, you are least likely to remember it but you understand the meaning of those words. However, if you hear words spoken loudly and emotionally, you would remember key phrases and words and the meaning of the speech. This indicates louder voices trigger your fight or flight response in the brain, which enhances your memory recall major parts of the speech.
- Our auditory system tend to focus on significant messages, differences in regular speaking patterns and a meaningful speech as well as loud, soft or unique cues. These aspects of speech are likely to be encoded into memory, which can be recalled for future reference.
2. Motivation
Roebers, Moga & Schneider (2001) found subjects provided with an incentive to report produced highly accurate results compared to controls. This suggests the motivation for precision is sparked by encouragement to provide correct information.
3. Interference
- Interference eliminates the recency effect if it occurs between the input and the output of information longer than the holding time of short-term memory (15-30 seconds). Bjork & Whitten (1974) found this occurs when a person is provided subsequent information to recall preceding the recall of the initial information.
- It is possible for the last few words to be forgotten because of the distraction words that displace them from short-term memory. Since the last few words weren't memorised, they aren't consolidated into long-term memory.
- Cohen (1989) discovered an action physically performed during the encoding phase that coincides with interference is more likely to be recalled accurately.
- Although certain tasks such as counting backwards can influence memory recall, the effect of the empty delay interval is negligible because the subject can memorise the items in their working memory without interference. Roediger & Karpicke (2006) discovered recalling a few items may interfere and disrupt the memory recall of other items.
- Poltrock & MacLeod (1977) hypothesised the effect of interference on recency and primacy are relative, which is determined by the ratio rule (retention interval to inter item presentation distractor rate).
4. Context
- Eich (1980) claimed more items can be remembered if the environments during the learning and recall processes are closely matching. This suggests context cues play a role in enhancing the recall of newly learned meaningful information.
- For example, Godden & Baddeley (1975) found deep-sea divers demonstrated better word list recall when they learned the word list underwater rather than on land.
- Grant et al. (1998) found students studying in silence demonstrated improved exam performance rather than with background noise, because exams are typically conducted in silence.
- When you demonstrate better recall of material under one particular state, it is known as state-dependent retrieval. Carter & Cassidy (1998) found students studying while on antihistamine medication demonstrated better recall of the recently learned material if they were examined on such material while on antihistamines.
- A study by Block and Ghoneim (2000) found a correlation between marijuana use and significant impairments in memory retrieval.
- A study by Lundqvist (2005) found a correlation between cannabis use and loss of internal control and cognitive impairment, particularly impairment of attention and memory, during the period of intoxication. Furthermore, the study found an association between chronic cocaine use and impaired attention, learning, memory, reaction time and cognitive flexibility.
- Methylenedioxymethamphetamine (MDMA) use associated with impaired encoding of information into long-term memory, impaired verbal learning, decreased concentration and decreased efficiency at focusing attention on complex tasks.
6. Gender
- It’s known females demonstrate greater performance in episodic memory tasks such as delayed recall and recognition than males. Their performance is on par with males on working, immediate and semantic memory tasks.
- Guillem & Mograss (2005) discovered male brains have a leftward asymmetry compared to female brains, which suggests men and women use hemisphere of their brain to a different extent.
- Beyer (1998) found women exhibited a negative recall bias, which suggests they are likely to recall their mistakes compared to males.
- A eyewitness study by Yarmey (1991) found women demonstrated higher accuracy in recall for weight of suspects compared to men.
- A study by Yang et al. (2013) found listeners of an oral presentation recalled more information from a female speaker compared to a male speaker. Researchers theorised the woman's voice exhibited superior acoustics than the man's voice, ranging from high tones to low tones. The larger range of voice tone may enhance semantic encoding for pitches that stimulate the auditory component of the brain, which resonates the best in the ear.
- It is understood that people are more engaged with speakers with variable tones, which indicates words delivered with such tones stand out and are easily remembered.
- Females were found to remember non-verbal cues and associate the speech's meaning with gestures, whereas males were found to remember verbal cues and engage more with facts and actual words within a speech delivered by a speaker's voice that fluctuates in tone.
- Men demonstrate superior recall of recently read information such as a list of objects than women, whereas women can recall a person's voice better than men.
- Nevertheless, both men and female similarly recall changes in emotional tone when emotional words are annunciated.
7. Food consumption
- Vaisman et al. (1996) found a correlation between breakfast at school and improved cognitive function compared to controls and breakfast at home.
- Sayegh et al. (1995) found beverages concentrated in carbohydrates reduced self-reported depression, anger, confusion, carbohydrate cravings, as well as improved memory word recognition.
8. Physical activity
Raine et al. (2013) conclude that physical inactivity and low fitness due to poor health correlated with reduced cognitive health in children. This suggests physical activity played a role in memory encoding in the hippocampus.
9. Trauma and brain exposure
Seifert (2012) found humans suffering from fear and trauma exposure, brain injury, post-traumatic stress disorder, pain, or anxiety demonstrate limited recall memory apart from flashbacks from the past.
What are some phenomena of memory recall?
Defined as "knowing about knowing", metacognition associates with numerous states of conscious awareness known as 'feeling-or-knowing' states, such as the tip-of-the-tongue. Son (2004) hypothesised the function of metacognition is the detection of processing errors and active correction of such problems.
i. Mnemonics & cognitive strategies
- Mnemonic devices abbreviate long phrases or lists of words as a way to memorise and recall new information in a cognitively efficient manner.
- Example 1: BODMAS, which stands for Brackets, Order, Division, Multiplication, Addition and Subtraction. It orders priorities of mathematical operations when solving equations (left is highest priority, right is lowest priority).
- Example 2: ROYGBIV, which stands for Red, Orange, Yellow, Green, Blue, Indigo and Violet. The colours of the rainbow from top to bottom.
- Bermingham et al. (2013) explained mnemonics augment organised memory encoding, which minimise the amount of information to be processed and memorised. Moreover, it minimised the requirement of intentional resources during memory retrieval, which leads to external sources not required for memory recall.
- If people employ cognitive strategies that establish semantic connections for the brain to process and work efficiently, it would improve their memory of the information through those connections.
- Chunking is another useful cognitive strategy that dissects significant amounts of information into smaller chunks in order aid in recall e.g. large number sets
- For example, if you want to remember a telephone number such as 9034 8945, you can divide it into 2-digit and/or 3-digit chunks such as 90, 34, 89, and 45, or 903, 489, and 45.
- The Method of Loci (MOL) describes a person's ability to visualise a spatial environment that augments recall of information later. Rather than rote learning a list of items, individuals mentally stroll along a path, allocating those items in an imaginary place that subsequently need to be memorised. This involves manipulation of the information during the encoding process as individuals rehearse the list.
Example MOL:
You are riding on a train to work reading a newspaper with the front page news headline about a soccer match result between Manchester United and Liverpool. Later, you made a mistake on the crossword on the newspaper back page, so you used a rubber to remove the error. After you alight the train, you walk to a eatery called the Frog's Diner (with frog logo on sign), where you order a hamburger. However, a pigeon lands on your table and tries to peck your food but but you sway it away with your shoe.
- Qureshi et al. (2014) found students that utilised the MOL cognitive strategy performed exceptionally better on memory recall tasks than students who learned the list by reading.
https://en.wikipedia.org/wiki/Tip_of_the_tongue
- Whenever you attempt to retrieve a word or phrase from memory, but you struggle to recall that word or phrase despite knowing it in the first place. You would say: "It's on the tip of my tongue!"
- Whenever you experience the tip-of-the-tongue phenomenon, you partially recall a target word or phrase, such as the first letter, its syllabic stress, and similar sounding words, meanings, or both.
- You would feel being seized or mild anguish as you desperately try to search that particular word from your memory, before you feel relieved upon finding the target word.
- Both men women typically experience TOT during their young adulthood, middle age, and older adulthood no matter how many languages they are fluent in. However, research is required to understand whether TOT is also experienced in children.
- Schwartz (1999) found many languages other than English contain an idiom that refers to the TOT phenomenon referencing the tongue, mouth, or throat as a metaphor.
- The direct English translations of those idioms include "in the mouth and throat", "sparkling at the end of the tongue", "on the front of the tongue", "on the top of the tongue", "on the tip/point/head of the tongue" and "on the tongue".
Who first coined "tip-of-the-tongue"?
- The phrase "tip of the tongue" is likely borrowed from a colloquial French phrase avoir le mot sur le bout de la langue meaning "having the word on the tip of the tongue".
- In 1890, William James was the first person to describe the tip of the tongue phenomenon in his book The Principles of Psychology, but he didn't label it as such.
- In 1965, Sigmund Freud explored unconscious psychological factors of the TOT phenomenon, such as unconscious thoughts and impulses that result in familiar words being forgotten.
- In 1966, Harvard researchers Roger Brown and David McNeill conducted the first empirical research on the TOT phenomenon to determine whether the feeling of imminent retrieval was based on actual retrieval ability or an illusion. They read only the definitions of obscure words to test subjects, and asked them to name the object or concept that closely matches the definition. When the target word was later revealed, test subjects were asked whether they experience a TOT state.
3 types of positive TOT states were discovered:
-- The revealed word was recognised as it had been sought.
-- The word was recalled correctly prior to its reveal.
-- The word sought by the subject was recalled before the target word was revealed, however the recalled word wasn't the intended target.
Furthermore, test subjects that experienced a TOT state could identify:
-- First letter of the target word
-- Number of syllables of the target word
-- Similarly sounding words to the target word
-- Words of similar meaning
-- Syllabic pattern
-- Serial position of some letters in the target word better than would be expected by chance.
What are the causes of the TOT phenomenon?
The cause(s) of TOTs are currently unknown, however the hypotheses proposed can be categorised into 2 main points of view: the direct-access view and the inferential view.
i. Direct-access view
According to Schwartz (1999), this theory suggests the TOT state occurs due to memory strength being inadequate in information retrieval but is adequate to trigger the phenomenon. This refers to the person having direct access to the target word in their memory, despite it can't be recalled immediately.
-- Blocking hypothesis
- The blocking hypothesis implies retrieval cues bring forth responses that relates to the target and blocks the retrieval of the correct word, which results in the TOT phenomenon.
- One may acknowledge the retrieved words related to the target word are incorrect they struggle to retrieve the actual correct word due to this inhibition. The related words are labelled "blockers" because they block the target word from being retrieved.
- For example, if the target word is scarlet, then possible 'blockers' or related words that are retrieved include red, blood, crimson, violet, passion, hot, actress
- More research is required to support or refute this theory, even though measuring the effects of blockers on TOT occurrence is difficult.
- Bown & Haley (1998) argued phonological blockers (retrieved words sounding similar to the target word, e.g. dart and cart) augment retrieval of the target rather than hinder it. However, Jones and Langford (1987) asserted the opposite effect of phonological blockers, which caused the TOT stated.
- A study by Metcalf & Kornell found evidence of phonological blockers acting as a side effect rather than as a primer or an enhancer. The "incubation period" (i.e. time for unconscious processing of problems) allowed test subjects to retrieve the target word by the same amount for the original non-blocked TOTs and the blocked TOTs. This suggests phonological blockers have no effect on the retrieval or the causes of TOT states.
-- Incomplete-activation hypothesis
- This hypothesis suggests TOTs emerge when the target word stored in memory isn't sufficiently activated to be recalled but it can be sensed nonetheless.
- Accessing the target word in memory varies due to factors that influence its activation level, such as cues. If the target word is sufficiently activated, it may exceed the threshold level of the TOT state and be retrieved.
-- Transmission-deficit model
- This theory suggests semantic and phonological information is stored in different parts of memory and retrieved separately.
- It hypothesises the coincidence of the activation of the semantic aspect of the target word and lack of this activation transmitted to the phonological aspect of the target word leads to TOTs. Harley & Bown (1998) implied TOTs are triggered by transmission deficits of activation from the semantic memory bank to the phonological memory bank.
- Burke & MacKay posited the TOT state emerges due to the infrequent use of the target word, scarce use of the word, and ageing, all factors are related to weakened neural connections in memory.
ii. Inferential view
This point of view implies TOTs are accessible and emerge from clues associated with the target that one can logically process. In other words, it is suggested one infers their knowledge of the target word, and imminent retrieval depends upon the information that are accessible regarding the target word from their memory. It ignores the target word's presence in memory as influencing the creation of TOT states.
-- Cue-familiarity theory
This theory implies TOT phenomenon is triggered by intense feelings provoked by recognition of a familiar cue regarding the target word. This theory implies TOT phenomenon is triggered by intense feelings provoked by recognition of a familiar cue regarding the target word. Repetitive cues increase the chance of TOTs occurring compared to a single cue.
-- Accessibility heuristic
This heuristic implies TOTs are induced by the quantity and strength of the information retrieved from memory when the target word itself isn't retrieved. When one attempts to retrieve a target word, they are likely to experience TOT phenomenon if they retrieve more information related to the target word.
Which brain regions are involved in the TOT phenomenon?
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Shaded area in orange is the anterior cingulate cortex (ACC) |
- Anterior cingulate cortex (ACC)
- Posterior cingulate cortex (PCC)
- Right dorsolateral prefrontal cortex (DLPFC)
- Right inferior prefrontal cortex (RIPC)
- Bilateral anterior frontal cortex
- Posterior medial parietal cortex
- Bilateral lateral parietal cortex
- Bilateral superior prefrontal cortex
- Supramarginal gyrus
- Superior temporal gyrus
- Supplementary motor area
- Left insular cortex
On the other hand, activity in the parahippocampal gyrus decreased in the TOT state.
- The exact function of the above brain areas in the TOT phenomenon is currently unknown, but it may vary depending on the nature of the target word.
- For instance, if the target word is a person's name, the fusiform face area increases in activation as the person attempts to process the person's face. Therefore it is difficult to determine which areas are specifically involved in TOT states, and which areas are a byproduct of other cognitive functions.
- Maril et al. (2005) hypothesised the anterior cingulate cortex and the right dorsolateral prefrontal cortex function as a circuit to detect conflict between the feeling of knowing the target word and the failure of recall.
- Schwartz et al. (2010) suggested the anterior cingulate cortex is involved due to the emotional response associated with the TOT state.
- Since the posterior medial parietal cortex, bilateral lateral parietal cortex, and the bilateral superior prefrontal cortex are involved in retrieval and evaluation, Maril et al. (2005) suggested those brain areas are implicated in the metacognitive processes associated with the TOT phenomenon such as the evaluation of the person's own knowledge and the probability of retrieving the correct information.
What factors influence TOT phenomenon?
1. Bilingualism
- Gollan et al. (2005) found occurrence of TOTs is higher amongst bilinguals than monolinguals for non-proper words compared to proper names, as well as the use of non-dominant language.
- Moreover, Ivanova & Costa (2008) found bilingual speakers took more time to respond when naming pictures compared to monolinguals, even with their first and dominant language, which implies bilinguals use those words infrequently than monolinguals.
- It is theorised bilinguals know virtually twice as many words and additional cognitive processes for activation and inactivation of languages, which may increased processing burden.
2. Drugs
-- Lorazepam
- Lorazepam is a type of benzodiazepine that treats anxiety, insomnia, acute seizures triggering sedation in both hospitalised and aggressive patients.
- Bacon et al. (2007) found a correlation between Lorazepam and increased incorrect recall responses to TOT states and inhibited retrieval of correct responses.
- They found test subjects who consumed lorazepam were oblivious of their incorrect responses and only experienced the subjective feeling of TOT states after they were informed of their incorrect responses.
- It suggests lorazepam suppresses brain regions involved with emotions, which may explain the lack of subjective feelings associated with TOT states.
- Therefore, it is concluded lorazepam has no effect on the probability of TOT, but rather inhibit the retrieval of correct responses and the subjective feeling of TOT states.
-- Caffeine
- Lesk & Womble (2004) found an association between small doses of caffeine (equivalent to 2 cups of coffee) and reduced short-term recall of particular words. Therefore, this disproves the theory that caffeine augments attention.
- However, there is a correlation between decreased TOT states and caffeine, which indicates better memory recall.
3. Ageing
- Studies have found that the frequency of TOTs increases with age, with reduced vocabulary, reduced phonological information about the target word.
- Shafto, Stamatatis & Tam (2009) found an association between increased TOT states and age-related grey matter loss in the left insula and increased activity in the prefrontal cortex and the sensorimotor cortex.
- Galdo-Alvarez, Lindin & Diaz (2009) suggested these findings imply a TOT occurs when the older brain continues to search for the target word upon the failure of the retrieval process. Priming words during the work retrieval process can decrease the frequency of TOTs and increase the probability of retrieving the target word.
- Shafto et al. (2007) concluded these findings support the spreading activation model, which states frequently activated neural connections are strengthened.
4. Emotions
- Schwartz (2010) stated that the occurrence of TOTs is influenced by bouts of negative emotions, thus emotional TOTs are likely to be recalled later than TOTs with no emotional experience attached. It suggests TOTs informs the cognitive system regarding the accessibility of the information being recalled. Furthermore, TOTs is demonstrated to occur from questions inducing emotional arousal.
- One brain area associated with both TOT phenomenon and emotion is the anterior cingulate cortex (ACC).
5. Disorders
-- Anomic Aphasia
- Anomic aphasia is defined as the inability to recall words the names, commonly seen in patients with aphasia and Alzheimer's disease (AD).
- Beeson, Holland, and Murray (1997) found patients with anomic aphasia demonstrated better recall of famous people compared to patients with Alzheimer's disease, Broca's aphasia and conduction aphasia.
- Nevertheless, there was no difference in immediate or delayed naming of famous faces between people with Broca's conduction and AD.
- All groups provided basic semantic information for at least 50% of the words presented, which indicates several words could potentially trigger TOT.
- People with conduction and Broca's aphasia demonstrated more incidence of TOT, and performed superiorly than other groups in identifying the initial letters of the target words.
Hanly & Vandenberg (2009) found dyslexic children experienced TOT states more frequently than non-dyslexic children, as well as demonstrated more errors in the phonological phase of word retrieval. However, dyslexic children were able to recall the semantic meaning behind each word that triggered a TOT state.
6. Priming
- Examples of priming for the target word include providing the first letter of the target word or a word that sounds similar to the target word. e.g. If the target word is violence, subjects can be primed with the letter "v" or the word "violins".
- Rastle & Burke (1996) found priming and practice helped decrease the probability of TOT states when attempting to recall infrequently-used information. This suggests the recency of information use impacts the retrieval process of that information.
- Abrams & Rodriguez (2005) found priming words that are phonologically similar to the target word both increases and decreases TOT states. Moreover, priming words from the same syntactic class as the target word had no effect on resolving TOT states. It is suggested the earlier in the word list the priming word is, resolution of the TOT state is less likely.
7. Age of acquisition
Navarrete et al. (2015) stated words acquired early in life can be retrieved more swifty and accurately than words acquired later in life, known as the age of acquisition effect. Therefore, the chance of TOT phenomenon increases when one attempts to retrieve late-acquired words.
iii. Involuntary memory retrieval
- In 1885, Hermann Ebbinghaus first recognised the principle of involuntary memory, stating that "often, even after years, mental states once present in consciousness return to it with apparent spontaneity and without any act of the will; that is, they are reproduced involuntarily."
- So far, only 2 types of involuntary memory retrieval were identified: (a) autobiographical and (b) semantic.
- Involuntary autobiographical memory (IAM) retrieval is induced by sensory cues and internal cues, such as thought or intention, which impact people in their daily lives by persistently and instinctively activating unconscious memories through priming. Studies hypothesised human goals and intentions, as well as physical cues in the surrounding context, often lead to the retrieval of related IAM. Ball & Little (2006) posited an error in memory self-regulation leads to unrelated autobiographical memories transferred to the conscious mind, which support the theory of metacognition being the most salient type of experience.
- Involuntary semantic memory (ISM) retrieval, or "semantic-popping", emerges in the same manner as IAM retrieval, but the difference is the retrieved memory tends to be trivial, such as a random word, image, or phase. ISM retrieval can be induced by spreading activation, which involves words, thoughts and concepts activating related semantic memories continually. Kvavilashvili & Mandler (2004) suggested spreading activation accumulated over a considerable amount of time before a random semantic memory "pops" into consciousness.
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| This is a visual representation of Spreading Activation |
iv. False memories
- Steffens & Mecklenbräuker (2007) stated repeated exposure to persistent beliefs, implications from authority figures, or false information can impact the reorganisation of a person's memory, which jumbles its details, or instils vivid false accounts of an event, known as a false memory.
- False memories are typically explained by source-monitoring error, where a person recalls specific facts, but fails to identify the source of that fact due to apparent loss of the association between the episodic and semantic accounts of the facts.
- e.g. Cryptomnesia, or inadvertent plagiarism, involves duplication of a work one previously encountered believing it to be their original idea.
- It is theorised false memories can also be caused by the generation effect, which is a phenomenon induced by repeated exposure to a belief, suggestion, or false information is easily remembered with each subsequent generation.
- The misinformation effect is also relevant to false memories, which involves bystander accounts of one event influencing eye-witness accounts of the same event, or by suggestion from an authority figure.
v. Focal retrograde amnesia
- Focal retrograde amnesia (FRA) or functional amnesia is defined as the inability to remember information preceding the traumatic event but knowledge acquisition is unaffected (i.e. no anterograde amnesia).
- Kapur et al. (1992) stated people with FRA may remember how to use objects and perform skills (implicit memory) but specific knowledge of personal events or previously learned facts (explicit memory) may be inaccessible or forgotten.
- Kopelman (2000) suggested FRA is a symptom of a variety of different disorders, cognitive deficits, or conditions resulting in disproportionate loss of explicit memory, thus leading to disproportionate retrograde amnesia (DRA).
- It is known FRA correlates with impairments in the temporal and frontal lobes, but it only correlates with the symptoms of retrograde amnesia.
vi. The Face Advantage
- Brédart & Barsics (2009) defined the Face Advantage as the the ability to recall information and memories through the presentation of a person's face rather than a person's voice.
- Mansour & Lindsay (2010) outlined 3 stages of memory recall during face perception, which include (1) recognition, (2) semantic memory and episodic memory retrieval, and (3) name recall.
- Studies found participants were able to recall celebrity names when presented with their faces rather than with their voices.
- Bruce & Young (1986) found information regarding the celebrity's name is recalled quicker and more accurately during face perception compared to voice perception. It is implied the neural connections between face representations and semantic and episodic memory are stronger than that of audio representations.
What are some neuropsychological tests of memory recall?
- California Verbal Learning Test:
https://en.wikipedia.org/wiki/California_Verbal_Learning_Test
- Rey Auditory Verbal Learning Test (AVLT)
- Philadelphia Verbal Learning Test (PVLT)
Which brain regions are involved in memory?
https://en.wikipedia.org/wiki/Neuroanatomy_of_memory
1. Hippocampus
- This brain structure is part of the limbic system, which is located adjacent to the medial temporal lobe. It is composed of 2 smaller structures: Ammon's Horn, and the Dentate Gyrus, each comprising of different types of neurons.
- Ward (2009) found the hippocampus contained a collection of neurons called 'place cells', which activate when an organism situated in certain locations considered unique. It suggested individual place cells not only responded to one unique location only, but the patterns of these cells' activity overlap to generate layered mental maps within the hippocampus.
- The right hippocampus is more involved in responding to spatial aspects, whereas the left hippocampus is more involved in dealing with context information.
- This is a theory that the hippocampus can expand upon experience in developing extensive mental maps.
- Mahut et al. (1982) found damage to the hippocampus and its adjacent areas lead to anterograde amnesia, the inability to encode new memories. This implies the hippocampus plays a role in both storing cognitive maps and encoding new information into short-term memory.
- Lesion studies also discovered the hippocampus plays a role in memory consolidation, which is a slow process of transitioning short-term to long-term memory.
- Furthermore, the hippocampus is implicated in the formation of new episodic memories rather than new semantic memories. This indicates explicit descriptions of episodic events can't be learned and a form of meaning and knowledge are acquired from semantic experiences.
2. Cerebellum
- Located at the brain's rear, next to the spinal cord, this brain region is involved in the encoding of procedural memory, and motor learning, such as coordination and fine motor control. e.g. Playing the piano for the first time.
- Damage to the cerebellum lead to difficulties in conscious movement, especially the coordination, timing and precision of such movements, and as initiating long-term changes in order improve motor skills.
3. Amygdala
- This brain region is located above the hippocampus in the medial temporal lobes, one in each hemisphere. Neuroscientists know the amygdalae play a role in both emotional learning and memory, since it reacts strongly to emotional stimuli, particularly fear.
- Thus, they aid in encoding and reinforcing emotional memories, leading to emotional events deeply and precisely encoded into memory.
- Robbins et al. (2008) found lesions to the amygdalae decrease motivation, as well as the processing of emotions.
- Rat experiments on classical (Pavlovian) conditioning have uncovered the amygdala's role in fear conditioning. Furthermore, the basolateral nucleus is highly active during the encoding of memories relating to fear.
- Rabinak & Maren (2008) described the central nucleus' role in the behavioural responses corresponding with the basolateral nucleus' response to fear. McGaugh (2004) implicated the central nucleus' role in emotions and behaviours motivated by food and sex.
- McGaugh (2004) found the amygdala plays an important role in memory consolidation, especially during occasions of high emotional arousal. This evinced the amygdala amplifies the emotional aspect of the information being encoded, leading to deeper processing of memory, making it unforgettable.
4. Basal Ganglia
- These group of nuclei are located in the medial temporal lobe, above the thalamus and linked to the cerebral cortex.
- It includes the following structures: globus pallidus, ventral striatum and dorsal striatum (putamen and caudate nucleus), subthalamic nucleus and substantia nigra.
- It plays fundamental roles in cognition, learning, and motor control and activities. Mishkin et al. (1987) implicated the basal ganglia also played an integral role in learning, memory, and subconscious memory mechanisms, such as the motor skills and implicit memory.
- Crespo et al. (2012) suggested a region within the ventral striatum called the nucleus accumbens plays a role in the consolidation, retrieval and reconsolidation of drug memory.
- Packard & Knowlton (2002) suggested the caudate nucleus is involved in learning and memory of associations taught through operant conditioning. This indicated the caudate nucleus aids in acquiring stimulus-response habits, and in solving sequence tasks.
- Damage to the basal ganglia can lead to dysfunctions in learning of motor and perceptual-motor skills, as well as motor dysfunction, and difficulty mental switching between working memory tasks.
- Examples of motor disorders include athymhormic structure, dystonia, Fahr's syndrome, Huntington's disease and Parkinson's disease.
Cortical structures
1. Frontal Lobe
- They are located at the front of each cerebral hemisphere and anterior to the parietal lobes. Kuypers (1981) found the primary motor cortex sits between the frontal lobe and parietal lobe, which is involved in voluntary movements of specific body parts linked to the precentral gyrus.
- The frontal lobe plays a fundamental role in planning, organisation, writing, concentration and controlling the movements of the limbs, as well as personality and behaviour.
- This area was implicated in the coordination of information stored in working memory. e.g. Determining the most efficient route from home to an unfamiliar restaurant by considering available information such as maps provided by GPS, traffic patterns, and roadworks.
- Frankland & Bontempi (2005) suggested the frontal lobes plays a role in the selection of memories relevant on a certain occasion, which can coordinate various pieces of information into a rational engram.
- Johnson et al. (1993) referred to the process of combining concrete information and the sources of such information into one memory representation as 'source monitoring'. In situations where information becomes isolated but fails to recall the source of such information, source monitoring errors would occur.
- Winograd (1988) proposed the frontal lobes played a role in prospective memory, which is the ability to remember the list of objectives to be completed in the future.
2. Temporal Lobe
- This region of the cerebral cortex is located under the Sylvian fissure on both hemispheres of the brain. Conway & Pleydell Pearce (2000) thought the temporal lobe is involved with memory, especially autobiographical memory.
- Rugg & Yonelinas (2003) suggested the temporal lobes plays a role in recognition memory, which is the capacity to identify an item that was recently noticed.
- Kolb & Whishaw (1990) reported damage to the temporal lobe cause numerous disturbances to auditory sensation and perception, selective attention of auditory and visual inputs, visual perception, organisation and classification of verbal stimuli, language comprehension, as well as changes in personality, and impairments to long-term memory.
3. Parietal Lobe
- This brain region is located behind the central sulcus, superior to the occipitial lobe, and posterior to the frontal lobe, literally on the top of the head. Blakemore & Frith (2005) defined the parietal lobe's features separated by 4 anatomical boundaries in the brain.
- Its main functions include: (1) sensation and perception, and (2) construction of a spatial coordinate system to map the world around us.
- Kardel et al. (1991) implied the parietal lobe augments the moderation of attention span and manifests spatial awareness and navigational skills, as well as integrates all sensory information (touch, pain, sight, smell, hearing, taste, etc.) to generate a single perception.
- Furthermore, it gives humans the capability to pinpoint their attention on different stimuli simultaneously (i.e. multi-tasking), as well as aid in verbal short term memory thanks to the supramarginal gyrus.
- Damage to the parietal lobe leads to neglect syndrome, which describes how patients treat aspects of their body or objects in their visual field as if it didn't exist at all.
- Warrington & Weiskrantz (1973) found damage to the parietal lobe's left side leads to Gerstmann syndrome, with symptoms such as left-right confusion, agraphia, acalculia, aphasia, and impaired object perception.
- Damage to the parietal lobe's right side lead to contralateral neglect, impairment of self-care skills (e.g. dressing and cleaning), as well as constructional apraxia, anosognosia, and impaired drawing abilities.
- Since the right parietal lobe regulates attention to both left and right visual fields, neglect syndrome is more prevalent on the right side of the parietal lobe.
4. Occipital Lobe
- This region is located at the back of the brain, as part of the forebrain. It positions above the cerebellum, posterior to the parieto-occipital sulcus. Its main function is visual perception.
- It contains an area called the Primary Visual Cortex (V1), which receives visual information from the Lateral Geniculate Nucleus (LGN). V1 sorts the information and projects them to a choice of 2 streams: dorsal stream or ventral stream.
- Goodale & Milner (1992) explained the ventral stream is involved in object recognition and representation, whereas the dorsal stream is involved is involved in the objects' position in space relative to the observer.
- Damage to the occipital lobe can lead to visual field impairments, scotomas, movement and colour discrimination, illusions, hallucinations, dyslexia, and akinetopsia.
- Kandel et al. (1991) found tumours in the occipital lobe cause contralateral damage to the visual field (i.e. visual defects on the opposite site). Furthermore, they discovered damage to the occipital lobe's left side leads to language inconsistencies, such as difficulty in identifying letters, numbers and words, and inability to integrate visual stimuli in order to discern the numerous ways an object can be perceived. On the other hand, damage to the occipital lobe's right side lead to non-verbal symptoms such as difficulty identifying geometric shapes, difficulty recognising faces and figures.
What happens if the cortex is damaged?
i. Frontotemporal lobar degeneration (FTLD)
- A type of dementia characterised by neurodegeneration in the frontal and temporal lobes.
- Symptoms include impairments in autobiographical memory, particularly episodic recall but semantic recall was spared.
ii. Parkinson's disease (PD)
- Characterised by neurodegeneration to the basal ganglia and associated memory regions.
- Symptoms include impairments to working memory and spatial memory, impairments to visuospatial memory, as well as dysfunction to encoding visuospatial memory into long-term memory.
- Montomery et al. (1993) stated working memory difficulties become apparent as sufferers of PD perform sequence tasks and experience events in time, along with tasks relying on memory such as the timing of strategy change or maintaining a train of thought.
How are memories consolidated?
https://en.wikipedia.org/wiki/Memory_consolidationhttps://www.sciencedirect.com/topics/neuroscience/memory-consolidation
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4526749/
https://www.frontiersin.org/articles/10.3389/fncom.2014.00064/full
- Memory consolidation is a process that reinforces a short-term memory after its initial procurement.
- It was first described by renowned Roman teacher of rhetoric Marcus Fabius Quintillian around the 1st century AD.
- In 1882, the mechanism of memory consolidation was proposed by Theódule-Armand Ribot with his Law of Regression.
- A few years later, William H. Burnham expanded the concept in his publication about amnesia, which combined findings from his experiments in psychology and neurology.
- The phrase 'memory consolidation' was coined by German scientists Müller and Alfons Pilzecker after understanding the notion that memory requires time to consolidate in their studies conducted between 1892 and 1900.
- After discovering the fact that newly learnt information during the consolidation of encoded old information can disrupt this process, this lead to the researchers' suggestion of the perseveration-consolidation hypothesis.
- McGaugh theorised new memories are delicate in nature, hence consolidation of such memories requires time and cognitive effort.
- Throughout the 1960s and 1970s, systematic studies of anterograde amnesia were conducted primarily on a patient named Henry Molaison, formerly known as patient H.M.. After his lobotomy on certain areas of his brain that was causing epileptic symptoms, he suffered from memory impairments.
- The findings concluded from numerous scientists would make this case a landmark of memory research. I'll discuss more about the case of patient H.M. in the section about anterograde amnesia.
- Researchers understood that the processes of memory consolidation and encoding occurred in the hippocampus and medial temporal lobe.
- Advancements in technology, animal models, cellular preparations, neuropharmacology, molecular biology, and neurogenetics have helped the study of consolidation evolve.
There are 3 different types of memory consolidation: synaptic consolidation, systems consolidation and reconsolidation.
(a) Synaptic Consolidation
https://www.sciencedirect.com/topics/psychology/synaptic-consolidation
- Also known as late-phase LTP, synaptic consolidation is a process that involves changes in synaptic protein synthesis and alterations in membrane potential triggered by the activation of intracellular transduction cascades.
- The molecular cascades subsequently activate transcription factors, which stimulate changes in gene expression. Therefore, this causes changes in synaptic proteins, and synaptic remodelling and growth.
- Dudai (2004) found any disruptions to the early phases of the learning process such as the molecular cascade, expression and processing of both transcription factors and immediate early genes, can impede synaptic consolidation.
i. Long-term potentiation
- Known as prolonged strengthening of synapses, it increases the amount of neurotransmitter produced and the receptor's sensitivity to an action potential, which lasts minutes or even days.
- LTP is one of several processes contributing to synaptic plasticity and synaptic growth, which are associated with memory formation, as well as memory consolidation, and learning.
- Researchers postulated LTP plays a fundamental role in Pavlovian fear conditioning in rats, hence learning and memory in mammals too.
ii. Timeline of consolidation
Synaptic consolidation takes less time to accomplish, compared to systems consolidation. Dudai (2004) estimated synaptic consolidation occurs within minutes or hours of memory encoding or learning. In addition, a minimum training record of around 6 hours would deem memories unaffected by interferences that disrupt synaptic consolidation and the formation of long-term memory.
iii. Spacing effect
- Studies have found distributed learning augments memory consolidation, particularly relational memory. When one undertakes distributed learning over the course of 24 hours, it reduces the rate of forgetting compared to massed learning, as well as augments the formation of relational memories.
- Litman & Davachi (2008) pointed out the mechanisms of synaptic strengthening depend on the spacing of memory reactivation to permit adequate time for protein synthesis to transpire, therefore consolidate long-term memory.
- In 1984, Smith and Rothkopf performed a experiment that demonstrates the spacing effect. They found participants who spaced out their study sessions and learnt in different environments aided memory retention. This suggested spacing out periods of information encoding provides the brain sufficient time to consolidation the newly learnt information without disturbances by new information.
iv. Protein synthesis
Gold (2006) found that protein synthesis plays an important role in learning and LTP, hence memory consolidation. However, more research is required to understand the relations between the biochemical implications of protein synthesis and learning.
(b) Systems Consolidation
https://www.cell.com/trends/cognitive-sciences/fulltext/S1364-6613(18)30264-X
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This form of memory consolidation involves transferring memories from the hippocampus to the neocortex for long-term storage. It is a dynamic process that fully develops in humans after 10 - 20 years. |
i. Standard model
- Squire & Alvarez (1995) explained the standard model describes how newly encoded information is retained in both the hippocampus and cortical regions.
- Dudai (2004) found the connections in the hippocampus become active in conscious or unconscious recall such as in sleep and 'offline' mechanisms.
- Frankland & Bontempi (2005) estimated memory is stored in the hippocampus for approximately a week after the initial learning stage. This suggested the hippocampus 'teaches' the cortex about the information, which becomes consolidated if recalled frequently. Therefore, memory from the hippocampus is gradually transmitted to the neocortex where it goes into long-term storage.
- This implied the hippocampus can store memories temporarily due to rapid synaptic changes, whereas the neocortical synapses change after a long period of time.
- Squire & Alvarez (1995) also conjectured that areas around the medial temporal lobe (MTL) associated with consolidation of memories within the neocortex by producing a binding area for a number of cortical regions involved in the initial stage of memory encoding.
ii. Multiple trace theory
- Multiple trace theory (MTT) hypothesises the hippocampus is always involved in the retrieval and storage of episodic memories, and other brain structures such as the neo-cortex involved in the encoding of semantic memories.
- Nadel & Moscovitch (1997) suggested the long-term connections between the hippocampus and neo-cortex during the ageing of memories, which establishes certain aspects of memory within non-hippocampal areas.
- Haist, Gore & Mao (2001) argued the hippocampus doesn't play a major role in recollecting distant memories after a period of several years. Based on fMRI data, there is a distinction between the hippocampus and the entorhinal cortex in remote memory retrieval. In addition, they question the accuracy of memories during testing, because they believe the initial interview in the scanner may have contributed to the encoding event as such differences between recent and remote memories would be obscured.
- Nadel & Moscovitch (1997) found amnesic patients with damage to their hippocampi exhibit traces of memories, which indicates other brain regions apart from the hippocampal system take part in memory retention.
- They asserted these retained memories lack the richness of experience, thus remain as depersonalised events that were semanticised over time.
- They posit this finding supports the theory that episodic memories rely heavily on the hippocampal system but semantic memories can be produced in brain regions, thus are unaffected by damage to the hippocampus.
iv. Declarative vs. procedural memory
- Typically stored in the mediotemporal lobe and the hippocampal systems, declarative knowledge includes the conscious recall of facts, episodes, and lists.
- Squire (1986) suggested procedural knowledge is consolidated in brain regions associated with motor skills (i.e. extrapyramidal motor system), since it includes knowledge related to methods, procedures, or operation of apparatus.
- Amnesic patients demonstrated the ability to learn and retain procedural knowledge on trained skills without realising training had ever occurred. This implied amnesia spares the patients' ability to learn certain motor, perceptual, and cognitive skills. Furthermore, amnesic patients are influenced by priming effects without being consciously able to recall any training session they participated in.
v. Emotional and stressful memory
- McGaugh (2000) associated the encoding of memorable experiences with the basolateral region (BLA) of the amygdala.
- McGaugh & Roozendaal (2002) implied stress hormones such as adrenaline play a fundamental role in memory consolidation in order to explain why stressful memories are vividly recalled.
- Gold & van Buskirk found a correlation between adrenaline and improved long-term retention of task-related memories. Furthermore, it indicates the retention level associates with the stress or emotionality level of the memory.
- Liang et al. (1986) hypothesised adrenaline influences memory consolidation by activating the amygdala because antagonism of β-adrenoreceptors blocked the retention of memory improvements. Moreover, β-adrenoceptor agonists elicit the opposite effect on the augmentation of memory consolidation.
- Studies suggest BLA plays an active role in memory consolidation and is affected by stress hormones, which leads to increased activation of BLA, thus increases memory retention. BLA subsequently communicates with the hippocampus to strengthen memory.
- Packard & Chen (1999) discovered a relationship between the hippocampus and augmented consolidation during food-rewarded maze tasks. In addition, memory consolidation was inhibited when the amygdala was inactivated by lidocaine.
vi. Sleep consolidation
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768102/
- Walker et al. (2005) stated rapid eye movement (REM) sleep plays an important role in the learning process overnight by consolidating information in the hippocampal and cortical brain areas.
- Ribeiro (1999) found REM sleep increases neuronal activity after an enriched or novel experience during wakefulness, therefore it enhances neuronal plasticity and augments memory consolidation.
- Vertes (2004) argued consolidation is unlikely during REM sleep because the brain is in a non-memory encoding state, which explains the lack of memory deficits in task learning among REM sleep-deprived animals and humans.
- Gas et al. (2005) discovered low acetylcholine levels in the central nervous system (CNS) during slow-wave sleep plays an essential role in memory consolidation and in the learning process.
- Walker et al. (2005) found sleep post-training enhanced both speed and accuracy in a finger-tapping task, which indicates the activity of both cortical and hippocampal regions has increased.
- Vertes (2004) hypothesised memory consolidation occurs independently of sleep because of its timing after sleep and the effects of sleep on motor learning.
- When neural patterns established during the learning phase are reactivated during sleep in the hippocampus, it is labelled as "replay". The replay phenomenon doesn't occur exclusively to sleep, because both rats and primates demonstrate signs of replay during restful-awake periods. This indicates replay may be a residual activation in brain regions previously involved in the learning phase, which implies replay has no effect on memory consolidation.
- Wamsley et al. (2010) discovered several memory traces associated with the hippocampus are reactivated in NREM sleep after a learning task, which boosted performance on such task. Furthermore, Wamsley et al. (2010) assumed dreams emerge from the reactivation of certain brain regions in order to explain why dreams are unrelated to the consolidated information.
- Wilhelm et al. (2011) discovered retrieval expectancy influenced information retention, which suggests sleep likely enhanced consolidation of information relevant to future events or behaviours.
- Gais et al. (2006) found growth hormones play a role in supporting general brain systems and memory function, however it is unclear whether they are involved in the formation and processing of memories during certain sleep periods.
- Schreiner et al. (2021) stated a correlation between memory consolidation during sleep via reacttivation of prior experiences and EEG sleep signatures such as cortical "slow oscillations" and spindles complexes.
- Ribeiro (1999) suggested an immediate early gene (IEG) called Zif268 plays a role in neuroplasticity during REM sleep after pre-exposure to an enriched environment.
(c) Reconsolidation
- Tronson & Taylor (2010) defined memory reconsolidation as previously consolidated memories being recalled and subsequently consolidated. This process maintains, strengthens and moderates memories already stored in the long-term memory.
- This theory is still controversial and hotly debated by numerous researchers, due to the conflicting evidence.
- Solyom et al. (1969) first proposed the theory of memory reconsolidation after discovering electroconvulsive shock therapy (ECT) can eliminate phobias. Dudai (2004) found ECT was effective on reconsolidating retrieved memories if administered directly after the retrieval of a memory. This suggests ECT disrupts the process of re-consolidating retrieved excited or fear memories.
- Nader, Schafe, & LeDoux (2000) suggested consolidated fear memory transitions to an adjustable state that requires de novo protein synthesis for reconsolidation. Furthermore they showed the reconsolidation process increases the malleability of memories. Results from their experiment found rats injected with anisomycin before memory consolidation and reconsolidation failed to retain the fear response upon hearing a sound tone. It suggests interference before memory consolidation influence the reconsolidation process of such fear memories later.
- A study by Brunet et al. (2008) on Post Traumatic Stress Disorder (PTSD) patients found inhibition of stress hormone receptors in the amygdala significantly decreased PTSD symptoms, which reduces the emotional aspect of memories.
- A systematic analysis by Tronson & Taylor (2007) found several studies failed to demonstrate memory impairments after inhibiting the reconsolidation process, which highlighted the need for standardising methods of measuring the effects of blocking brain areas associated with reconsolidation.
- Since certain forms of memory reactivation may indicate novel extinction learning rather than activation of an old memory trace, it is possible inhibiting reconsolidation may maintain the original memory trace but prevent the consolidation of extinction learning.
- Gräff et al. (2014) suggested reconsolidation may be inhibited by epigenetic modifications of histone deacetylase, but more research is required to fully understand this phenomenon.
Several key principles are outlined to prove disruption of a previously consolidated memory is specific to the reactivation of the original memory trace.
-- Demonstrate the volunerability of reactivation occurs in a limited time frame, by delaying infusion until 6 hours after activation
-- Demonstrate the behavioural measure used to assess disruption of memory isn't only induced by task impairment but rather the process, by using control groups with no original learning.
-- Rule out alternative explanations, such as extinction learning by extending the reactivation phase.
The next part of memory will focus on the different types of memory and the physiology and genetics of memory.
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