Memory

Define memory.

Define memory.

the mental process involved in receiving, storing + recovering information

Define capacity.

the amount of info that can be held in the memory store

Define duration.

the length of time info can be held in memory

Define coding.

the format in which info is stored in various memory stores

what is the capacity of short term memory

limited to 7+ or - 2

what is the capacity of long term memory

unlimited

what is the duration of long term memory

up to a lifetime

what is the duration of short term memory

18-30 seconds

what is the coding of short term memory

mainly acoustic

what is the coding of long term memory

mainly semantic

what are the three types of memory

• sensory register

• short term memory

• long term memory

what is the sensory register

it temporarily stores information from our senses + it’s constantly receiving info. Unless we pay attention to the info, spontaneous decay occurs (info stays for less than one second). Has an unlimited capacity + a very limited duration. Info is coded depending on sense that picked it up

what is the capacity of the sensory register

unlimited

what is the duration of the sensory register

very limited

who researched the sensory register

Sperling

Outline Sperling’s research into the sensory register

• lab experiment

• participants shown grid with 3 rows of 4 letters for 0.05 secs

• had to immediately recall either whole grid or a randomly chosen row indicated by a tone played straight after grid was shown

• when participants had to recall whole grid, they could recall 4-5 letters (average)

• when participants had to recall a particular row, they could recall 3 letters, no matter which row

• means almost whole grid was held in sensory register

who researched the capacity of short term memory

• Jacobs

• Miller

who researched the capacity of long term memory

Ramscar

who researched the duration of short term memory

Peterson + Peterson

who researched the duration of long term memory

Bahrick

who researched coding

Baddeley

Outline Jacobs research into the capacity of short term memory

• technique to measure digit span: participants given a string of digits (e.g. 4 numbers in a row) + have to repeat list of numbers aloud in correct order. List of numbers increases until participant can’t recall them in correct order (this determines their digit span)

• mean span for digits was 9.3 items

• mean span for letters was 7.3

• shows capacity of STM is limited to around 7-9 items

what was the procedure of Jacobs research into the capacity of short term memory

technique to measure digit span: participants given a string of digits (e.g. 4 numbers in a row) + have to repeat list of numbers aloud in correct order. List of numbers increases until participant can’t recall them in correct order (this determines their digit span)

what were the findings + conclusion of Jacobs research into the capacity of short term memory

• mean span for digits was 9.3 items

• mean span for letters was 7.3

• shows capacity of STM is limited to around 7-9 items

outline Millers research into the capacity of short term memory

• aim: to investigate capacity of STM + see whether chunking assists memory in short term

• participants read strings of numbers which they had to recall immediately after in correct order. Length of list gradually increases until participants could only recall lists correctly in 50% of trials. Included trials where he chunked numbers into small groups

• capacity of 7 + or -2 (magic number)

• if chunks are used, capacity= 7 + or -2 chunks

• it’s the chunks of data that limit memory, but it doesn’t matter how much goes into each chunk

what was the procedure of Millers research into the capacity of short term memory

participants read strings of numbers which they had to recall immediately after in correct order. Length of list gradually increases until participants could only recall lists correctly in 50% of trials. Included trials where he chunked numbers into small groups

what were the findings + conclusions of Millers research into the capacity of short term memory

• capacity of 7 + or -2 (magic number 7 + or -2)

• if chunks are used, capacity= 7 + or -2 chunks

• it’s the chunks of data that limit memory, but it doesn’t matter how much goes into each chunk

evaluation of research into capacity of short term memory (AO3)- positives

• Millers research has useful real life applications (e.g. chunking to remember phone numbers)

• Jacobs research is supported by Millers (both found capacity is 7 + or -2). Consistent findings mean conclusion regarding capacity of STM is reliable

evaluation of research into capacity of short term memory (AO3)- negatives

• Millers research into chunking can’t be applied to many types of memory tasks used in real life, so has limited application

• Millers conclusion that it doesn’t matter how much info goes into each chunk has been criticised by Simon, who found it did matter how many items were in each chunk. In Simon’s study, participants had a shorter memory span for larger chunks

• artificial lab environment: participants may have concentrated more + put more effort in than they would normally to impress researchers, so results lack ecological validity. Findings are difficult to generalise to real life memory settings

Outline Ramscars research into the capacity of long term memory

• trained computers to mimic elderly peoples brains

• found that as computers aged by acquiring more info they slowed down, suggesting human brains slow down because there’s more knowledge to sift through

outline Peterson + Petersons research into the duration of short term memory

• aim: to find out how long items remain in STM without rehearsal

• presented participants with consonant trigrams (e.g. CDX). Participants told to count backwards in 3s from a specific number. After intervals of 3-18 secs participants were asked to stop counting + recall the trigram

• participants able to recall about 80% of trigrams correctly after interval of 3 secs, but less than 10% after 18 secs

• info decays rapidly from STM without rehearsal

• STM duration= about 18 secs

what was Peterson + Peterson’s aim in their research into the duration of short term memory

how long items would remain in STM without rehearsal

what was Peterson + Peterson’s procedure in their research into the duration of short term memory

• presented participants with consonant trigrams (e.g. CDX)

• participants told to count backwards in 3s from a specific number

• after intervals of 3-18 secs participants were asked to stop counting + recall the trigram

what were Peterson + Peterson’s findings + conclusion in their research into the duration of short term memory

• participants able to recall about 80% of trigrams correctly after interval of 3 secs, but less than 10% after 18 secs

• info decays rapidly from STM without rehearsal

• STM duration= about 18 secs

evaluation of research into duration of short term memory (AO3)- positives

• highly controlled lab conditions: allowed them to use control procedures (e.g. counterbalancing to reduce order effects). Reduced extraneous variables increase internal validity

• repeated measures design used, which eliminates individual differences in memory performance which allows cause + effect between IV (number of secs without rehearsal) + DV (ability to recall trigram) to be seen

evaluation of research into duration of short term memory (AO3)- negatives

• highly artificial- trigram task isn’t a realistic task that people carry out in their day to day lives. Study lacks ecological validity, so is harder to generalise to real life situations (e.g. revising for A-levels)

• trigrams from earlier trials may have caused confusion, interfering with memory in later trials. This could have led to poor recall rather than limited duration of STM

outline Bahricks research into the duration of long term memory

• aim: to find duration of LTM + see whether there was a difference for duration when using recognition or recall tasks

• tested memory of 392 graduates of an American high school for their former classmates from a 50 year period (used high school yearbooks)

• two conditions: half were given a list of names + asked to select the photo that matched the name (recognition group), other half were asked to name people in photos without list of names (recall group)

• 15 years after graduation, recognition group were 90% accurate + recall group were 60% accurate

• 48 years after graduation, recognition group were 70% accurate + recall group were 30% accurate

• people can remember certain types of info for almost a lifetime

• accuracy of LTM is better when measured by recognition tests rather than recall tests

what was the aim of Bahricks research into the duration of long term memory

aim: to find duration of LTM + see whether there was a difference for duration when using recognition or recall tasks

what was the procedure of Bahricks research into the duration of long term memory

• tested memory of 392 graduates of an American high school for their former classmates from a 50 year period (used high school yearbooks)

• two conditions: half were given a list of names + asked to select the photo that matched the name (recognition group), other half were asked to name people in photos without list of names (recall group)

what were the findings + conclusion of Bahricks research into the duration of long term memory

• 15 years after graduation, recognition group were 90% accurate + recall group were 60% accurate

• 48 years after graduation, recognition group were 70% accurate + recall group were 30% accurate

• people can remember certain types of info for almost a lifetime

• accuracy of LTM is better when measured by recognition tests rather than recall tests

evaluation of research into duration of long term memory (AO3)- positives

• high external validity because real life meaningful memories were studied, so results reflect our memory of real life events + can be applied to everyday human memory

evaluation of research into duration of long term memory (AO3)- negatives

• confounding variables weren’t controlled- participants could’ve looked at yearbook photos + rehearsed memory over the years

• sample of 392 American uni graduates lacks population validity, so can’t generalise results to other populations (e.g. UK students). So unable to conclude whether other populations would demonstrate same ability to recall names + faces after 50 years

• research is unable to explain whether LTM becomes less accurate overtime because of a limited duration or whether LTM simply gets worse with age. So unable to determine if LTM has unlimited duration which is affected by factors like age, or if LTM has a limited duration

what are substitution errors

when people substitute an item on a list for a different similar item

outline Baddeley’s research into coding in the short + long term memory

• aim: to investigate types of coding in STM + LTM

• lab experiment- gave different lists of words to 4 groups of participants to remember:

  • acoustically similar (sound similar) words

  • acoustically dissimilar (don’t sound similar) words

  • semantically similar (similar meanings) words

  • semantically dissimilar (not similar meanings) words

• participants shown original words + asked to recall them in correct order immediately after hearing them repeatedly (STM) + again after 20 minutes (LTM)

• STM findings:

  • acoustically similar words were harder to recall in correct order (55%) than acoustically dissimilar words (75%)

  • similarity of meanings only had slight effect

• LTM findings:

  • recall was worse for semantically similar words (55%) than for semantically dissimilar words (85%)

  • recall was the same for acoustically similar + dissimilar words

• STM= acoustic coding

• LTM= semantic coding

what was the aim of Baddeley’s study

to investigate types of coding in STM + LTM

what was the procedure of Baddeley’s study

• lab experiment- gave different lists of words to 4 groups of participants to remember:

  • acoustically similar (sound similar) words

  • acoustically dissimilar (don’t sound similar) words

  • semantically similar (similar meanings) words

  • semantically dissimilar (not similar meanings) words

• participants shown original words + asked to recall them in correct order immediately after hearing them repeatedly (STM) + again after 20 minutes (LTM)

what were the findings + conclusion of Baddeley’s study

• STM findings:

  • acoustically similar words were harder to recall in correct order (55%) than acoustically dissimilar words (75%)

  • similarity of meanings only had slight effect

• LTM findings:

  • recall was worse for semantically similar words (55%) than for semantically dissimilar words (85%)

  • recall was the same for acoustically similar + dissimilar words

• STM= acoustic coding

• LTM= semantic coding

evaluation of Baddeley’s research into coding (AO3)- positives

• highly controlled lab experiment with control over variables (e.g. words used, instructions + rehearsal times). This reduces effects of extraneous variables, which increases internal validity of findings

evaluation of Baddeley’s research into coding (AO3)- negatives

• independent groups design, therefore individual differences in memory mean it’s difficult to compare IV (coding) to DV (recall)

• task used is artificial- material wasn’t personally meaningful to participants so caution should be taken when generalising results to how info is coded by STM + LTM in real life situations. In real world, semantic coding would be used by STM, so findings have limited application

who came up with the multi-store model of memory

Atkinson + Shiffrin

multi-store model of memory AO1

• memory is a linear flow of info through 3 stores (sensory register, short term memory + long term memory)

• info enters sensory register in original sensory form + stays there for less than 1 second

• if you pay attention to the info it moves into STM (encoded acoustically, capacity of 7+ or -2, duration of 18-30 secs)

• info in STM may be forgotten due to decay or displacement

• if info is rehearsed it moves into LTM (encoded semantically, unlimited capacity, duration of up to a lifetime)

• info in LTM may be forgotten due to interference or retrieval failure

• for info to be remembered it must be retrieved from LTM + passed back to STM via rehearsal loop

evaluation of multi-store model of memory (AO3)- positives

• evidence for distinction between STM + LTM: Peterson + Peterson’s trigram study shows duration of STM is 18-30 secs, whereas Bahrick’s yearbook study shows duration of LTM is unlimited. This suggests STM + LTM are separate store, as suggested by MSM

• Bahrick’s study has high external validity- real life meaningful memories were studied, so results reflect memory for real life events + can be applied to everyday human memory. This strengthens support of MSM which Bahrick’s study provides

• HM had problems in LTM after brain surgery- couldn’t remember events from last 45 years but STM remained intact. Suggests there are separate LTM + STM stores, like in MSM

evaluation of multi-store model of memory (AO3)- negatives

• Peterson + Peterson’s trigram study is highly artificial- it’s not a realistic task people carry out in their day to day lives. It lacks ecological validity, so is difficult to generalise to real life. This weakens the support of MSM which Peterson + Peterson’s study provides

• HM is a case study, so can’t generalise findings to rest of population (lacks population validity). This weakens support of HM for MSM

what are the two models of memory

• multi-store model of memory

• working memory model

who came up with the working memory model

Baddeley + Hitch

what would a diagram of the working memory model look like

• central executive at the top

• visuo-spatial sketch pad, episodic buffer + phonological loop below

• LTM at the bottom

what is the working memory model a model of

short term memory

working model of memory AO1

• model of short term memory

• STM isn’t a passive temporary store for info, but rather an active store

• central executive:

  • involved in problem solving + decision making

  • an attentional process that monitors incoming info

  • allocates slave systems to tasks

  • modality free

  • has a very limited capacity

• phonological loop:

  • stores + processes a limited amount of verbal + written info for brief periods (independent from visuo-spatial sketch pad)

  • preserves order info arrives

  • consists of phonological store (stores words you hear) + articulatory process (allows maintenance rehearsal of items stored in phonological store)

• visuo-spatial sketch pad

  • sets up + manipulates mental images

  • has a limited capacity (independent from phonological loop)

  • subdivided into visual cache (stores visual info) + inner scribe (records arrangement of objects in the visual field)

• episodic buffer

  • maintains a sense of time sequencing

  • storage component of central executive

  • limited capacity of up to 4 chunks

  • links working memory to long term memory

what does the central executive do in the working memory model

• involved in problem solving + decision making

• an attentional process that monitors incoming info

• allocates slave systems to tasks

• modality free

• has a very limited capacity

what does the phonological loop do in the working memory model

• stores + processes a limited amount of verbal + written info for brief periods (independent from visuo-spatial sketch pad)

• preserves order info arrives

• consists of phonological store (stores words you hear) + articulatory process (allows maintenance rehearsal of items stored in phonological store)

what does the visuo-spatial sketch pad do in the working memory model

• sets up + manipulates mental images

• has a limited capacity (independent from phonological loop)

• subdivided into visual cache (stores visual info) + inner scribe (records arrangement of objects in the visual field)

what does the episodic buffer do in the working memory model

• maintains a sense of time sequencing

• storage component of central executive

• limited capacity of up to 4 chunks

• links working memory to long term memory

evaluation of the working memory model (AO3)- positives

• supported by Baddeley + Hitch research: dual task shows 2 tasks can be performed simultaneously in STM, suggesting there’s a supervisory component dividing our attention in STM, as suggested in WMM

• supported by Baddeley’s study where participants found it hard to perform 2 tasks simultaneously, showing VSS has a limited capacity. But participants could perform a visual + verbal task at the same time, showing the capacity of the VSS + phonological loop are separate

• KF was injured in a motorbike accident + was able to recall info from LTM but had issues with STM. He struggled to recall words presented verbally, suggesting his phonological loop was damaged, but his visuo-spatial sketch pad wasn’t. This suggests there are at least 2 components in STM (1 for visual info, 1 for acoustic info), which supports the idea of 2 separate slave systems in WMM

• evidence from brain scans shows different parts of the brain are active during verbal + visual tasks, showing VSS + PL are 2 separate components

• better explanation of memory than MSM: it’s more complex + sophisticated + is more likely to reflect complexities of human memory. It’s accepted as the most accurate model of STM

evaluation of the working memory model (AO3)- negatives

• role of the central executive is unclear because it’s difficult to design tasks to test the central executive

• some argue that the central executive is made up of several components. Eslinger + Damasio studied EVR (who had a cerebral brain tumour removed). EVR could perform reasoning tasks well, but had poor decision making abilities, suggesting there are separate components within the central executive for dealing with reasoning + decision making

• most research used to support the WMM lacks ecological validity because it was a lab experiment, therefore might not be representative of how memory works in the real world

define eye witness testimony

evidence provided by a person who witnesses a crime with a view to identifying a perpetrator of the crime. Accuracy may be affected during encoding, storage + retrieval

what 2 factors affect the accuracy of eye witness testimony

• misleading information (leading questions + post event discussion)

• anxiety

anxiety affecting eye witness testimony (AO1)

Loftus:

• aim: to find out if anxiety during a witnessed incident affects accuracy of later identification

• procedure:

  • lab experiment

  • half of participants overheard a low-key discussion in a lab about equipment failure, person emerged from lab holding a pen with grease on his hands

  • half of participants overheard a heated + hostile exchange in a lab. Heard glass breaking + chairs crashing + a man emerged holding a bloodstained paper knife

  • participants given 50 photos + asked to identify person who came out of lab

• findings: those who witnessed man holding pen accurately identified him 49% of the time + those who witnessed man holding knife accurately identified him 33% of the time

• conclusions: weapon focus- witness concentrates on weapon + this distracts attention from appearance of perpetrator. Anxiety decreases accuracy

what is weapon focus

witness concentrates on weapon + this distracts attention from appearance of perpetrator

outline Loftus’ study

Loftus:

• aim: to find out if anxiety during a witnessed incident affects accuracy of later identification

• procedure:

  • lab experiment

  • half of participants overheard a low-key discussion in a lab about equipment failure, person emerged from lab holding a pen with grease on his hands

  • half of participants overheard a heated + hostile exchange in a lab. Heard glass breaking + chairs crashing + a man emerged holding a bloodstained paper knife

  • participants given 50 photos + asked to identify person who came out of lab

• findings: those who witnessed man holding pen accurately identified him 49% of the time + those who witnessed man holding knife accurately identified him 33% of the time

• conclusions: weapon focus- witness concentrates on weapon + this distracts attention from appearance of perpetrator. Anxiety decreases accuracy

evaluation of Loftus (AO3)- positives

• lab experiment so high level of control over extraneous variables (e.g. same 50 photos, same time between incident + recall, same man), so confident that anxiety did affect accuracy of EWT

• support from Deffenbacher: meta-analysis of 18 studies looking at effects of anxiety on EWT. Showed high levels of anxiety decreased accuracy of EWT

evaluation of Loftus (AO3)- negatives

• lab experiment is an artificial setting so it lacks ecological validity + is difficult to generalise to real life situations. So can’t be sure that anxiety lowers accuracy of EWT in real world

• contradicting evidence from Yuille + Cutshall: found anxiety increases accuracy of EWT in real life situations

what’s the Yerkes-Dodson law

states that performance improves with increases in arousal/ anxiety up to an optimal point + then decline with further increases in arousal/ anxiety

what effect do lab experiments say that anxiety has on the accuracy of eye witness testimonies

anxiety decreases the accuracy of eye witness testimonies

what effect do field experiments say that anxiety has on the accuracy of eye witness testimonies

anxiety increases the accuracy of eye witness testimonies

Discuss the effect of anxiety on the accuracy of eye witness testimony (16 marks)

AO1 (6 marks):

• Loftus:

  • aim: to find out if anxiety during a witnessed incident affects accuracy of later identification

  • procedure:

    • lab experiment

    • half of participants overheard a low-key discussion in a lab about equipment failure, person emerged from lab holding a pen with grease on his hands

    • half of participants overheard a heated + hostile exchange in a lab. Heard glass breaking + chairs crashing + a man emerged holding a bloodstained paper knife

    • participants given 50 photos + asked to identify person who came out of lab

  • findings: those who witnessed man holding pen accurately identified him 49% of the time + those who witnessed man holding knife accurately identified him 33% of the time

  • conclusions: weapon focus- witness concentrates on weapon + this distracts attention from appearance of perpetrator. Anxiety decreases accuracy

AO3 (10 marks):

• positive: Deffenbacher meta-analysis supports that anxiety decreases accuracy

• negative: lab experiment so has low ecological validity- artificial so difficult to generalise to anxiety affecting accuracy in real world

• negative: Yuille + Cutshall found anxiety increases accuracy of EWT in real world situations

• contradictions can be explained by Yerkes-Dodson law: performance improves with increases in arousal (which explains anxiety increasing accuracy in real world) up to an optimal point + then declines with further increase in arousal (which explains anxiety decreasing accuracy in lab experiments)

how many different long term memory stores are there

three

what are the three different types of long term memory

• episodic

• semantic

• procedural

who found out that there are different types of long term memory

Tulving

what did Tulving use to find out that there are different types of long term memory

PET scans (cognitive neuroscience research)

describe episodic memory

• ability to recall events (episodes) from our lives

• like a diary

• e.g. what you had for breakfast

• memory of a single episode includes several elements (e.g. people + places)

• declarative (easy to put into words)

• coded with time + place

• time-stamped (remember when they happened)

• requires conscious effort to recall

• less resistant to forgetting

• right prefrontal cortex is associated with episodic memory

describe semantic memory

• knowledge of the world (facts)

• like an encyclopaedia + dictionary

• e.g. taste of an orange + meanings of words

• declarative (easy to put into words)

• not coded with time + place

• not time-stamped (don’t remember when we learnt fact)

• requires conscious effort to recall

• less resistant to forgetting

• left prefrontal cortex is associated with semantic memory

describe procedural memory

• memory for actions + skills (how we do things)

• e.g. riding a bike

• non-declarative (not easy to put into words)

• not coded with time + place

• not time-stamped (don’t remember when we learnt how to do)

• doesn’t require conscious effort to recall

• resistant to forgetting

• different brain regions are associated with procedural memory

which brain region is associated with episodic memory

right prefrontal cortex

which brain region is associated with semantic memory

left prefrontal cortex

which brain region is associated with procedural memory

different brain regions

is episodic memory declarative or non-declarative

declarative

is semantic memory declarative or non-declarative

declarative

is procedural memory declarative or non-declarative

non-declarative

is episodic memory coded with a time (time-stamped) + a place

yes

is semantic memory coded with a time (time-stamped) + a place

no

is procedural memory coded with a time (time-stamped) + a place

no

is episodic memory resistant to forgetting

no

is semantic memory resistant to forgetting

no

is procedural memory resistant to forgetting

yes

does episodic memory require conscious effort to recall

yes

does semantic memory require conscious effort to recall

yes

does procedural memory require conscious effort to recall

no

what does evidence from PET scans suggest about long term memory

different types of long term memory are stored in different parts of the brain

positive evaluation of types of long term memory (AO3)

• evidence from HM case study: HM’s episodic memory was damaged (he couldn’t recall events from his past e.g. death of his parents + Vietnam war). Semantic memory was intact (he knew what words meant). Procedural memory was intact (he could tie his shoe laces, speak + walk).

• neuroimaging evidence: evidence from Tulving’s PET scans suggest left prefrontal cortex was involved in recalling semantic memories, whereas right prefrontal cortex was involved in recalling episodic memories, which supports idea of separate LTM stores.

• real life application: it’s useful to be able to pinpoint exactly which type of LTM is impaired as this helps provide targeted treatments. Older people with mild cognitive impairment often have impairments in episodic memory, so researchers have developed training techniques to help them improve their episodic memory+ avoid negative consequences of age related decline.

negative evaluation of types of long term memory (AO3)

• problems with HM + CW case studies: small sample size so lacks population validity

• contradictory evidence: Cohen + Squire disagreed with Tulving + suggested only 2 types of LTM (non-declarative + declarative)