Memory - Memory Model (STM, LTM, MSM, WMM) Flashcards
1
Q
What is the duration of STM?
A
- 18-30 seconds (without rehearsal)
2
Q
What was the procedure of Peterson and Peterson’s study?
A
- Peterson and Peterson (1959)
- ppts (24 undergrad students) were shown a consonant trigram
- then asked to count backwards in 3s to prevent rehearsal of trigram
- after 3, 6, 9, 12, 15, 18 sec intervals, they repeated the trigram (done using different ones)
3
Q
What were the results of the STM duration study?
A
- 3 secs = 90%
- 9 secs = 20%
- 18 secs = <10%
- shows how information can quickly decay if not rehearsed
- the max. duration of STM is 18 - 30s (more research into STM has been carried out)
4
Q
What are the strengths of Peterson and Peterson’s study?
A
- lab experiment:
- tightly controlled variables
- e.g. no. of trigrams, how long they were presented
- can be replicated to get reliable results
5
Q
What are the weaknesses of Peterson and Peterson’s study?
A
- unrealistic:
- these nonsense trigrams do not represent activities that take place in every day life
- so it has low ecological validity
- there may have been interference:
- the previous trigrams may have caused confusion
- the results can be questioned as it could have been due to the ppts forgetting or interference
6
Q
What is the duration of LTM?
A
- 30-50 years (lifetime)
7
Q
What was the procedure of Bahrick’s study?
A
- Bahrick et al (1975)
- 400 American ppts were asked to identify/match names to pics/recall their former classmates
- (after 48 years) names to faces = 70%
- free recall with no picture cue = 30%
- supports the idea that LTM can last a lifetime
- also suggests that individuals are able to access the info in their LTM much easier when cues are presented
- ** so cues are often need to help with retrieval **
8
Q
What are the strengths of Bahrick’s study?
A
- high external validity:
- researchers investigated meaningful material (remembering classmates)
- so it has a higher ecological validity than Peterson’s study
- also gives a better estimate of the duration of LTM
9
Q
What are the weaknesses of Bahrick’s study?
A
- less control of IV (natural experiment):
- likely that some names may have been rehearsed (if classmates were still in touch etc.)
- making it a confounding variable, so the results may have been invalid
- specific information:
- names of classmates is particularly meaningful/regularly rehearsed
- so not all LTMs remain for a lifetime
10
Q
What is the capacity of STM?
A
- limited
- Jacobs (9 digits and 7 letters)
- Miller (7 +/- 2)
11
Q
How did Jacobs (1887) study the capacity of STM?
A
- serial digit span technique
- the researcher read out 4 digits and ppt had to repeat it back immediately
- more digits were added until the ppt was unable to repeat it back
- results:
- 9 digits and 7 letters were correctly recalled
- capacity increased with age
- some may have used strategies like chunking to improve their digit span
- ** digits are easier to remember than letters **
12
Q
What are the strengths/weaknesses of Jacobs’ study?
A
- study has validity as it has been repeated and similar results have been obtained
- lacks ecological validity:
- learning random lists of numbers and letters is not a realistic method
- more meaningful info may be recalled better (STM may have greater capacity)
- other factors:
- previous sequences recalled by ppts may have confused them on later trials
- this may have been a confounding variable (affecting the results of this study)
- not sure whether extraneous variables (IQ levels, distractions) were controlled
13
Q
What did Miller (1956) believe the capacity of STM was?
A
- 7 +/- 2 items
- he believed that it could be increased through “chunking”
- Cowan (2001) revives this and argued that the capacity of STM was around 4 chunks (lower end of ‘7 +/- 2’)
14
Q
What are the three ways information can be coded?
A
- acoustic:
- storing info based on the way it sounds
- semantic:
- coding info based on its meaning
- visual:
- storing info in terms of its looks
15
Q
How is information stored in the STM?
A
- mainly encoded in acoustic form
16
Q
How is information stored in the LTM?
A
- mainly stored on the basis of its meaning (semantics)
17
Q
What was the procedure of Baddeley’s study?
A
- Baddeley (1966):
- ppts were shown a sequence of 5 words under one of the four conditions
- they had to immediately write them down in order
- acoustically similar
- acoustically dissimilar
- semantically similar
- semantically dissimilar
18
Q
What were the results of this study?
A
- immediately tested (STM) = least accurate with acoustically similar (commonly got them muddled)
- tested 20 mins later (LTM) = least accurate with semantically similar
- shows how info is normally coded acoustically in the STM and semantically in the LTM
19
Q
What are the strengths/weaknesses of Baddeley’s study?
A
- clear difference:
- supports he idea of there being two different ways of encoding in the STM/LTM
- low ecological validity:
- the results cannot be applied to real life as meaningless lists were used (no personal relevance)
- so it does not tell us much about coding memories in everyday life (limited application)
20
Q
What is the Multi-Store Model?
A
- introduced by Richard Atkinson and Richard Shiffrin (1968)
- argue that memory involves a flow of info through stages in a fixed linear sequence
- sensory register (unlimited capacity, 250 ms duration)
- STM
- LTM
- Env. Input —> S.R. —> (attention) STM [recall + rehearsal loop] <—> [rehearsal + retrieval] LTM
- info is detected by sense organs then enters the SR (coding depends on the sense)
- attention payed = STM
- rehearsed (from STM) = LTM
- info (STM) will decay within 30 secs if maintenance rehearsal does not occur
- prolonged rehearsal moves it to the LTM
21
Q
What is the sensory register?
A
- stores sensory info from the environment for a short period of time
- Atkinson and Shiffrin proposed that there are 5 separate sensory stores
- iconic = visual
- echoic = auditory
- haptic = sensory (physical, internal muscle tensions)
- gustatory = taste
- olfactory = smell
- duration = 250 ms
- capacity =unlimited
- coding = depends on the sense (modality specific)
22
Q
What was the procedure of Sperling’s study?
A
- Sperling (1960)
- ppts were shown grid with 3 rows of 4 letters for 50 ms and had to immediately recall (whole grid, random row)
- particular row = ppts could recall on average 3/4 items
- suggests that almost the whole grid was held in their SR (large capacity, short duration)
23
Q
What are the strengths/weaknesses of Sperling’s study?
A
- highly scientific:
- the variables were tightly controlled as it was a lab experiment
- this makes it easy for someone to replicate
- lacks ecological validity:
- due to the artificial setting of the study
- people do not normally have to recall letters in response to a sound (results may not represent real life)
24
Q
What are the strengths of the MSM?
A
- explains primacy and recency effects:
- primacy = likely to remember words at beginning of list (enough time to rehearse), which moves into the LTM
- recency = likely to remember words at the end of list as they are still in STM
- Murdoch asked ppts to learn lists of words (10-40) and free recall them
- he found that ppts tended to remember the first few words and the last word (not the ones in the middle)
- STM = middle words been there too long (displacement)
- LTM = middle words not long enough (asymptote)
- case studies support idea of two separate stores (STM/LTM):
- Henry Molaisan (HM) was studied by Scoville and Milner (1957)
- his brain damage was caused by the removal of the hippocampus from both sides of his brain
- after the operation, his personality/intellect remained intact (could recall list of 6 numbers) but could not form LTMs
- support from brain-scanning techniques:
- Beardsley (1977) used brain scanning and found that different parts of the brain are active during STM/LTM tasks (e.g. prefrontal cortex = STM)
- Squire (1992) = also found that the hippocampus was active during LTM
- suggests how the STM/LTM are separate stores
25
What are the weaknesses of the MSM?
- ‘info must be rehearsed to move into LTM’ is an over simplification as MSM does not explain flashbulb memories:
- does not take into account that more relevant info is easier to remember
- rehearsing info that we do not understand will not stay in LTM for long period of time
- Cratik and Watkins proposed two types of rehearsal (maintenance and elaborative)
- maintenance = repeating info (STM)
- elaborative = *linking info to existing knowledge*/processing on a deeper level (LTM)
- MSM only focuses on one type of rehearsal
- Kulik and Brown found that highly emotional/significant/shocking events are *easily stored* without any rehearsal
- shows that, in some cases, rehearsal is not needed to form LTMs
- evidence suggests STM/LTM are not single stores:
- most studies supporting MSM lack ecological validity:
26
What are the types of LTM?
- implicit = cannot easily be described
- *procedural*
- procedural = skills learned, learning to do something
- explicit = can easily be described
- *episodic*
- *semantic*
- episodic = concerned with event/s occurring
- semantic = facts
27
What are the differences between the different LTM?
- conscious = episodic, semantic
- unconscious = procedural
- brain scans:
- different types of memory are stored in different areas of the brain
- semantic = may not recall when memories were learnt/encoded
- episodic = stored with reference to time and place
28
What are the strengths of the types of LTM?
- supported by case studies:
- HM, Clive Wearing had severely impaired episodic memories but could learn new skills (*procedural memory*)
- both also had a relatively intact semantic memory
- Clive Wearing had a viral brain infection yet he was still able to read music/play piano
- evidence from brain scans (PETs):
- Tulving (1989) asked ppts to try memory tasks and found that SM = frontal/temporal lobes, EM = prefrontal cortex
- real life applications:
- it has positive applications
- Belleville (2006) found that it is possible to improve episodic memories in elderly people with impairments
- this shows the benefit of distinguishing between different types of LTM (*specific treatments can be developed*)
29
What are the weaknesses of the types of LTM?
- gender differences:
- research cannot be generalised to all of the population (needs to be treated with caution)
- Herlitz (1997) assessed LTM in 1,000 Swedish ppts and found that females had better *episodic* LTM
- semantic = no difference
- women may have stronger episodic memories due to their *higher verbal abilities*
30
What is the Working Memory Model?
- Baddeley and Hitch (1974) believed STM was too simple
- they argued that the STM itself has sub stores and each is responsible for processing different types of information
- input —> S.R. —> (attention) Working Memory <—> LTM
- working memory model:
- central executive
- phonological loop
- visuo-spatial sketch pad
- episodic buffer
31
What is the central executive?
- has overall control over the three components
- processes info in all sensory forms and decides which ‘slave system’ is needed
- it has a *limited capacity* and cannot make many decisions at the same time
32
What is the phonological loop?
- temporarily stores/rehearses ‘word-based’ info in the order it arrives
- phonological store = inner ear
- holds info in speech-based form for 1-2 secs
- articulatory processes = inner voice
- rehearses info from the phonological store
- *limited capacity and duration*
33
What is the visuo-spatial sketchpad?
- known as the inner eye which *stores*/*manipulates* a limited amount of visual and spatial info for a brief period of time
- helps us keep track of where we are in relation to other objects as we move through our environment
- visual cache
- inner scribe
- *limited capacity and duration*
34
What is the episodic buffer?
- acts as a backup store which ‘communicates’ with LTM and integrates visual, station and verbal info processed by other stores
- records the order in which events take place
35
What was the procedure of Baddeley and Hitch’s (1976) study?
- to investigate if ppts can use different parts of working memory simultaneously
- ppts asked to perform two tasks at the same time (dual task)
- digit span task (repeat list of numbers)
- verbal reasoning task (true/false questions)
- as no. of digits increased, ppts took longer to answer
- they did not make any errors in the verbal reasoning as the numbers increased
- verbal reasoning = central executive
- digit span technique = phonological loop
36
What are the strengths of the WMM?
- accounts for dual-tasking:
- impaired = completing two tasks at once that are both visual/verbal
- not impaired = two tasks requiring different stores
- accounts for case studies like KF (shows STM has different stores):
- KF had a motorcycle accident and was still able to recall his LTM, but had issues with STM
- he was able to remember visual images but not sounds (acoustic info)
- supports the idea of the two slave systems, *phonological loop*/*visuo-spatial sketchpad*
- brain scanning evidence:
- D’Esposito (1995) used fMRI scans to test different components of WMM
- prefrontal cortex was activated when verbal/spatial tasks were performed together
- suggests that it is part of the *central executive*
- can explain how we carry out everyday tasks:
- phonological loop = verbal reasoning, comprehension, reading
- central executive = problem solving
- visuo-spatial = navigation
- it has a greater face validity than the MSM
37
What are the weaknesses of the WMM?
- exact role of central executive is not clear:
- argues that it directs attention and decides which slave system to use
- but the CE may also consist of sub components
- Eslinger and Damasio (1985) studied EVR (removed cerebral tumour) and found that his CE was intact but had *poor* decision making skills
- suggests that his CE was not actually properly intact
- single case studies may not be reliable:
- hard to make a generalisation about ‘normal’ memory processing as these case studies are unique to the individual
- e.g. KF’s brain damage
- supporting studies
