Lecture5:Memory.DrNaif

Use with Atkinson & Hilgard’s Introduction to Psychology 15th editionNolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning

Chapter 8

Memory


Three Important Distinctions

• Three stages of memory– Encoding stage – consists of placing a fact in memory– Storage stage – when the fact is retained in memory– Retrieval stage – occurs when the fact is recovered

from storage– Different stages mediated by different brain structures

– most of the regions activated by encoding are in the left hemisphere while most of the regions activated during retrieval are in the right hemisphere



• Three memory stores– Atkinson-Shiffrin theory

• Sensory information enters sensory store which is large, transient (lasts only few milliseconds), and the small amount of attended to information is then transferred to short-term memory

• Short-term memory – information you are conscious of, is readily accessible, subject to decay (over period of around 20 seconds) unless rehearsed or undergoes other processing (elaborating), in which case it will move to long-term memory

• Long-term store – unlimited store of the information generally available to us. Information enters via processes from short-term memory, and process of retrieval takes information back to short-term memory to be used for current task



• Different memories for different kinds of information– we may use different long-term memory for storing

facts than we do for retaining skills– Explicit memory – person consciously recollects

previous event, where recollection happens at particular time and place

– Implicit memory – person unconsciously remembers information of various kinds


Sensory Memory

• Sperling’s experiments: the partial-report experiment

– Iconic memory fades away over about a third of a second


Sensory Memory

• Visible persistence: the temporal integration experiment


Sensory Memory

• Partial report, visible persistence, and a theory that integrates them

– Two aspects of iconic memory being measured – the part that allows information to be extracted and part that was visible – have different characteristics

– The theory which integrates them proposes that briefly presented visual stimulus triggers a sensory response, the amount of information acquired from stimulus is related to area under sensory-response function, and the visibility of stimulus is related to the rate at which observer acquires information from the stimulus


Working Memory

• Working memory– Alternative term for short-term memory to highlight its

role in thinking rather than simply a storage space

• Encoding– To encode information into working memory, must

attend to it– Phonological coding – favours phonological code

(sounds of words/digits) to encode information when keeping it active through rehearsal

– Visual coding – can use visual code for verbal items but more important for non-verbal items


Working Memory

• Current conceptions of working memory– Working memory conceptualized as being divided into:

• Phonological loop – for storing & operating on information in an acoustic code

• Visual-spatial sketchpad – holds & operates visual/spatial information

• Mediated by different brain structures – phonological loop by the left hemisphere & visual-spatial sketchpad by the right

• Two systems controlled by the executive – directs attention & decides what operations performed on the information

• Additional component – episodic buffer which binds or associates different aspects of a memory


Working Memory

• Storage– Capacity of working memory limited – for the

phonological loop, memory span is seven items, give or take two (7 ± 2)

– Chunking – can use long-term memory to perform chunking – recoding new material into larger, more meaningful units & storing those in working memory

– Forgetting – occurs either because the items “decay” over time or are displaced by new items


Working Memory

RetrievalThe more items in working memory, the slower retrieval becomes


Working Memory

• Working memory and thought– When consciously problem-solving, we often use

working memory to store parts of the problem as well as relevant information accessed from long-term memory

• Transfer from working memory to long-term memory– Rehearsal – process of conscious repetition of

information which maintains an item in working memory (maintenance rehearsal) but can also cause it to be transferred to long-term memory (elaborative rehearsal)


Working Memory

• Division of brain labor between working memory and long-term memory– Working memory and long-term memory implemented

by different brain structures• Hippocampus – critical for long-term memory• Regions of frontal cortex – involved in working memory


Long-Term Memory

• Long-term memory– Involved in storing information from a few minutes to

as long as a lifetime

• Encoding– Encoding meaning – meaning is the dominant way of

representing verbal material in long-term memory– Adding meaningful connections – memory can be

improved by creating real or artificial links between items, e.g. by elaborating on the meaning of material while encoding it


Long-Term Memory

• Retrieval – poor memory often reflects retrieval failure rather than storage failure– Evidence for retrieval failures – unable to recall fact or experience

but recall it later or “tip-of-the-tongue”– Interference – related information interferes with retrieval process

of target memory. Interference is a major reason why forgetting from long-term memory increases with time as relevant retrieval cues become overloaded

– Models of retrieval – some based on the search process whereas others based on the activation process


Long-Term Memory

• Forgetting: loss of information from storage– Some forgetting due to retrieval failures but some

information almost certainly forgotten• Research suggests a function of the hippocampus is to

consolidate relatively new memories

• Interactions between encoding and retrieval– Organization – more we organize material, easier it is

to retrieve it– Context – easier to retrieve particular fact/episode if in

the same context as when you encoded it


Long-Term Memory

• Emotional factors in forgetting– Emotion can influence long-term memory in five ways

• Rehearsal: we think about emotionally-charged situations more than neutral ones

• Flashbulb memories: vivid & relatively permanent record of circumstances where one learned of a significant event (e.g. 9/11)

• Retrieval interference via anxiety – anxiety causes/associated with extraneous thoughts which interfere with memory retrieval

• Context effects – recall best when dominant emotion during retrieval matches that during encoding

• Repression – ultimate retrieval failure – access to target memories actively blocked


Implicit Memory

• Implicit memory – Explicit memory – a matter of consciously recollecting the

past whereas implicit memory is often shown in skills & involves improvement in perceptual, motor, or cognitive task without conscious recollection

• Memory in amnesia– Much of what is known about implicit memory is learned

from people with amnesia (partial loss of memory)• Anterograde amnesia – inability to acquire new factual information• Retrograde amnesia – inability to remember events which

occurred prior to injury or disease


Implicit Memory

• ...Memory in amnesia– Skills and priming – not all kinds of memory disrupted

• Amnesiacs have no difficulty remembering & learning perceptual and motor skills (explicit & implicit memory different systems)

• Prior exposure to stimulus facilitates (primes) later processing of that stimulus – amnesiacs have no difficulty here

– Childhood amnesia – few can recall events from first years of life

• Probably related to the massive difference in how young children encode experience & how adults organise memories

• Language development & maturation of hippocampus also likely to be factors


Implicit Memory

• A variety of memory systems– Explicit & implicit memory come in various forms

• Implicit memory – perceptual-motor skills & priming involve different memory stores (based on brain damage research)

• Explicit memory – two kinds – episodic (personal episodes) and semantic (general truths)

• Implicit memory in normal individuals– Research again suggests separate systems

• Brain-scanning studies show explicit memory accompanied by increased neural activity in certain regions while implicit memory accompanied by decrease in neural activity in critical regions


Constructive Memory

• Constructive Memory– Memory is constructive & reconstructive process –

memory for an event can, and does, depart systematically from the objective reality that gave rise to it at time of formation and later

• Constructive processes at the time of memory encoding– Construction of a false memory can occur at either

initial perception or during transfer from short-term to long-term memory (or both)


Constructive Memory

• ...Constructive processes at the time of memory encoding– Constructive perception – if what is originally perceived

differs from objective world through perceptual errors, the initial & subsequent memories will be distorted

– Generation of inferences – during transfer from short-term to long-term memory can draw inferences about information which is then stored with information – it is hard to then recall what the original information was and what was the inference


Constructive Memory

• Post-event memory reconstruction– Every time we revisit memory it changes in some fashion– Internally generated inferences – people make inferences

which they incorporate into their memory, e.g. using schemas, stereotypes etc.

– Externally provided suggestions – information provided by others may be incorporated into memory, e.g. suggestive information – can not only distort memories but can create entirely fictional memories


Constructive Memory

• Constructive memory & the legal system– Constructive memory particularly important in legal

system due to importance of witness testimony– Confidence and accuracy

• High confidence is normally predictive of high accuracy in memory except when circumstances are poor, e.g. an original event causes poor encoding, post-event reconstruction takes place or where there is motivation & opportunity to rehearse reconstructed memory


Constructive Memory

• ...Constructive memory & the legal system– Suggestive information and children’s memories

• Young children particularly susceptible to suggestive information, especially during interviews

– Forced confessions • Interrogation techniques are able to produce genuinely false

memories (& confessions) of crimes that suspects can be objectively shown not to have committed e.g. by being told there is evidence, that they were drunk/impaired, that they have “repressed” memory of crime or told they were suffering from a personality disorder


Constructive Memory

• Memory errors and normal memory– Memory illusions – occur when people confidently

“remember” events that never occurred• Source monitoring – attributing information in memory to its

source. Because it is based on inferences, it sometimes fails which helps explain some memory illusions, e.g. people may misattribute the source of post-event information for the event itself


Improving Memory

Chunking & memory span

For most capacity of working memory = 7 ± 2 but can increase size of chunk & so increase number of items in memory span


Improving Memory

• Imagery & encoding– Imagery is particularly useful for connecting unrelated

items at the time of encoding & therefore is used in systems for aiding memory, e.g. mnemonic system, & key-word method for learning foreign words

• Elaboration & encoding– The more we elaborate items, the more we can

subsequently recall or recognise them – more connections, greater the retrieval possibilities


Improving Memory

• Context & retrieval– Context serves as a cue for retrieval – if it cannot

physically return then can re-create context mentally

• Organization– Organization during encoding improves subsequent

retrieval – we are capable of storing & retrieving huge amount of information if we organize it appropriately, with hierarchical organization preferable


Improving Memory

• Practising retrieval– Another way to improve retrieval is practice, e.g.

asking yourself questions about what you are learning

Lecture5:Memory.DrNaif

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