memory

coding

how information is stores in the various memory stores

capacity

amount of information held in a memory store

duration

length of time information can be held in a memory store

study for coding

Baddeley

• 4 groups of participants given different lists of words to remember

• acoustically similar/dissimilar or semantically similar/dissimilar

• asked to recall worlds in correct order - immediately (STM) and also after 20 minutes (LTM)

information is coded ___ in STM

acoustically

information is coded ___ in LTM

semantically

findings from Baddeley study on coding

• when recalling immediately (STM) participants did worse for acoustically similar worlds

• when recalling after 20 mints (LTM) they did worse with semantically similar words

study on capacity - digit span

Jacobs

• research reads 4 digits

• participants recalls out loud in correct order

• if correct, then increases to 5 digits and so on

• once participant cant recall correctly - indicates their digit span

findings from Jacobs digit span study

• mean span for digits was 9.3 items

• mean span for letters was 7.3

study + findings on capacity - span

Miller

• made observations of everyday practice

• things come in 7 (days of the week, musical notes)

• span of STM 7 items +/- 2

chunking

Miller - grouping sets of digits or letters into units or chunks in order to remember more easily

study for duration of STM

Peterson and Peterson

• 24 students in 8 trials each

• given consonant syllable eg YCG to remember + given 3 digit number

• counted back from the number until told to stop (prevents mental rehearsal)

• told to stop after 3/6/9/12/15/18 seconds (retention interval) then recall the consonant syllable

findings of Peterson and Petersons STM duration study

• after 3 seconds, average recall was 80%

• after 18 seconds is was 3%

STM duration

about 18 seconds, unless verbal rehearsal

study for duration of LTM

Bahrick

• 392 american participants between 17 and 74

• high school yearbooks used

memory tested by

1) photo recognition test, some from yearbooks

2) free recall test - naming people from their graduation class

findings from Bahrick’s duration of LTM study

• participants who graduated within 15 years were 90% accurate in photo recognition

• free recall was 60%

• participants graduated with 48 years were 70% accurate for photo recognition

• free recall 30%

duration of LTM

may be up to a lifetime

strength of Baddeley’s study for coding

• identified clear difference between memory stores

• later research showed some exceptions

• idea of STM coded acoustically and LTM semantically has remained correct

• important step into understand memory - led to multi-store model

limitation of Baddeley’s study for coding

• used artificial stimuli

• word lists had no personal meaning to participants

• tell us little about coding in different memory tasks in everyday life

• people may use semantic coding for LTM when processing meaningful information

• findings have limited application

strength of Jacob’s study for digit span

• study had been replicated

• old study which often lacks valid control - digit spans may have been underestimated due to confounding variables

• repeats have been confirmed by better controlled studies

• valid test of digit span in STM

limitation of Millers study for span

• overestimated STM capacity

• review of other research concluded the span is more like 4 ± 1 chunks

• the lower end of the estimate is more accurate (5) than 7

limitation of Peterson x2 study for STM duration

• stimuli was artificial

• not completely irrelevant as we still remember fairly meaningless material eg. phone numbers

• but recalling consonant syllables doesn’t reflect everyday memory activities

• lacks external validity

strength of Bahrick’s study for LTM duration

• high external validity

• use of meaningful material (names and faces)

• studies of LTM with meaningless pictures had lower recall rates

• findings reflect a more accurate estimate of LTM duration

multi-store model (Atkinson and Shiffrin)

function of the multi-store model

describes how memory works in terms of 3 stores (sensory register, short-term memory, long-term memory) and how information is transferred from one store to another

sensory register

all stimuli from the environment passes into the sensory register

stores each of our 5 sense

coding of the sensory register

coding in each store is modality specific (depends on the sense)

iconic memory

visual information

echoic memory

acoustic information

duration of the sensory register

very brief - less than half a second

capacity of the sensory register

very high - over 100 million cells in one eye, each story data

how information passes from the sensory register further into the memory system

attention (paying attention to the information)

how we keep information in STM

maintenance rehearsal - repeating material over and over

how information is passed from STM to LTM

prolonged rehearsal - repeating the material for long enough

how we recall information from the LTM

transferred back into the STM by retrieval

case study HM

• brain surgery due to epilepsy went wrong - hippocampus removed from both sides of his brain (central to memory function)

• after operation - he thought it was 2 years earlier and remembered little of the operation

• couldn't form new long term memories

• performed well on STM tests

• supports separation of stores

MSM strength- research support

• studies differentiate STM and LTM

• Baddeley coding study - mix up acoustically similar words in STM and semantically similar with LTM

• capacity and duration studies also support the separation (Peterson/Bahrick)

• clearly show they are separate stores, supporting MSM

MSM limitation - invalid model for everyday life

• many studies supporting MSM use artificial stimuli that doesn't reflect things we remember in everyday life

• (Baddeley, Jacobs, Peterson)

• may not explain how memory works in everyday life where we remember meaningful information

limitation of MSM - multiple STM stores

• KF + other studies

• found there may be another STM store for non-verbal noises

• may be more than one STM store processing different types of information

KF case study

• motorbike accident resulted in brain damage + amnesia

• LTM remained intact but not STM

• digit span - low when words read aloud

• digit span test - words presented visually - better performance

• also, his STM for non-verbal noises was intact (eg dog barking)

• supports idea of multiple STM stores

limitation of MSM - prolonged rehearsal

• MSM says prolonged rehearsal = more likely to transfer into LTM

• studies found instead the type of rehearsal is more important

• elaborative rehearsal - linking information to existing knowledge + thinking about the meaning

• suggests info can be transferred into LTM without prolonged rehearsal

• MSM may not fully explain achievement of LTM storage

LTM - episodic memory + how it’s retrieved

personal events/memories

retrieved consciously with effort

LTM - semantic memory + how it’s retrieved

knowledge of the world/facts/concepts

retrieved consciously with effort

LTM - procedural memory + how it’s retrieved

knowledge of how to do things/skills

retrieved subconsciously and without effort

case study Clive Wearing

• severe form of amnesia from viral infection attacking his brain + damaging hippocampus

• used to be a world-class musician

• intact procedural LTM - can still play piano + conduct a choir

• faulty episodic LTM - doesn't remember his musical education

• remembers some aspects of life before infection eg.that he has children, but can’t remember their names

• faulty STM - greets his wife happily every time she walks in as if its been years

types of LTM strength - clinical evidence

• HM and Clive Wearing

• impaired episodic memory due to brain damage

• semantic + procedural memory stayed unaffected (could remember word meanings + how to speak/walk etc)

• supports different stores of LTM as one can be damaged while the others are unaffected

types of LTM limitation - control of studies

• clinical studies used as support often lack control of variables

• brain injuries were unexpected and couldn’t be controlled

• research doesn't know what their memory was like before the damage - no comparison

• limits what clinical studies can say tell us about types of LTM

types of LTM strength - real-world application

• allows psychologists to help people with memory problems

• age is linked to loss of episodic memory - recalling recent memories/events, though past ones remain intact

• Belleville designed an intervention to help improve episodic memories in older people - participants performed better on memory test after training than a control group

• distinguishing types of LTM enables specific treatment

types of LTM limitation - conflicting findings

• Buckner + Petersen - found semantic memory is located on the left side of the PFC, and episodic memory on the right

• other research links left PFC with encoding episodic memory, and the right with episodic retrieval

• challenges neurophysiological evidence supported type of LTM

The Working Memory Model (Baddeley and Hitch)

function of the WMM

explains how STM is organised and how it functions

components of the WMM

central executive, phonological loop, visuo-spatial sketchpad, episodic buffer

role of the central executive

supervisory role

monitors incoming data + focuses/divides attention + allocates subsystems to tasks

capacity of the central executive

very limited processing capacity, doesn’t store information

role of the phonological loop

deals with auditory information

• phonological store - stores words you hear

• articulatory process - allows maintenance rehearsal, repeats sounds/words in a loop to keep them in working memory

capacity of the phonological loop

2 seconds worth of what you can say

role of the visuo-spatial sketchpad

stores visual and/or spatial information

helps visualise things

components of the VSS

• visual cache - stores visual data

• inner scribe - records arrangement of objects in the visual field

capacity of the VSS

limited - 3 or 4 objects

role of the episodic buffer

temporary store for information

integrates visual, spatial and verbal information processes by other stores

maintains sense of time sequencing

storage component of the central executive

links working memory to LTM + wider cognitive processes

capacity of the episodic buffer

limited - about 4 chunks

WMM strength - clinical evidence

• KF

• poor STM for auditory information

• could process visual information normally

• could recall letters/digits better when he read them than when they were read to him

• his phonological loop was damaged but his visuo-spatial sketchpad was intact

• supports existence of separate visual/acoustic STM memory stores

WMM limitation - lack of controls

• KF may have had other cognitive impairments (not just damage to phonological loop) affecting his memory

• the trauma from the accident may have affected his cognitive performance severely

• challenges evidence coming from clinical studies of people with brain injuries

WMM strength - support for visuo-spatial sketchpad

• Baddeley study - participants were fine carrying out visual and verbal task at the same time (dual task)

• when both tasks were visual/verbal - performance declined

• because both visual tasks compete for same subsystem - VSS

• verbal + visual tasks dont compete

• evidence for a separate subsystems (VSS) that processes visual input, and one for verbal processing (PL)

WMM limitation - confusion over central executive

• lack of clarity over nature of the central executive

• its recognised as the most important component of memory - but is the least understood

• its defined as simply ‘attention’ whereas it needs to be more specified - some psychologists believe is may have subcomponents

• challenges the quality of the WMM

interference theory

explanation for forgetting in LTM

when 2 pieces of information disrupt each other - causes forgetting one or both or distortion of memory

harder to access information in LTM, interference makes it harder to locate them

proactive interference

when an older memory interferes with a newer one

retroactive interference

when a newer memory interferes with an older one

interference - study on effects of similarity

McGeoh and McDonald

• participants learned 10 words until they could remember them 100% accurately, then learned a new list

• 6 different groups for type of new word lists (synonyms, antonyms, unrelated to original list, consonant syllables, 3 digit numbers, no new list (control))

interference - findings of McGeoh and McDonald’s study on effects of similarity

• when recalling the original list - synonym group did the worst

• showed that interference was worst when memories are similar

• could be due to PI or RI