Memory - Memory Model (STM, LTM, MSM, WMM)

Question 1

What is the duration of STM?

Answer 1

• 18-30 seconds (without rehearsal)

Question 2

What was the procedure of Peterson and Peterson’s study?

Answer 2

• 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)

Question 3

What were the results of the STM duration study?

Answer 3

• 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)

Question 4

What are the strengths of Peterson and Peterson’s study?

Answer 4

• lab experiment:
  
  • tightly controlled variables
  • e.g. no. of trigrams, how long they were presented
  • can be replicated to get reliable results

Question 5

What are the weaknesses of Peterson and Peterson’s study?

Answer 5

• 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

Question 6

What is the duration of LTM?

Answer 6

• 30-50 years (lifetime)

Question 7

What was the procedure of Bahrick’s study?

Answer 7

• 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 **

Question 8

What are the strengths of Bahrick’s study?

Answer 8

• 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

Question 9

What are the weaknesses of Bahrick’s study?

Answer 9

• 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

Question 10

What is the capacity of STM?

Answer 10

• limited
  
  • Jacobs (9 digits and 7 letters)
  • Miller (7 +/- 2)

Question 11

How did Jacobs (1887) study the capacity of STM?

Answer 11

• 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 **

Question 12

What are the strengths/weaknesses of Jacobs’ study?

Answer 12

• 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

Question 13

What did Miller (1956) believe the capacity of STM was?

Answer 13

• 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’)

Question 14

What are the three ways information can be coded?

Answer 14

• acoustic:
  
  • storing info based on the way it sounds
• semantic:
  
  • coding info based on its meaning
• visual:
  
  • storing info in terms of its looks

Question 15

How is information stored in the STM?

Answer 15

• mainly encoded in acoustic form

Question 16

How is information stored in the LTM?

Answer 16

• mainly stored on the basis of its meaning (semantics)

Question 17

What was the procedure of Baddeley’s study?

Answer 17

• 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

Question 18

What were the results of this study?

Answer 18

• 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

Question 19

What are the strengths/weaknesses of Baddeley’s study?

Answer 19

• 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)

Question 20

What is the Multi-Store Model?

Answer 20

• 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

Question 21

What is the sensory register?

Answer 21

• 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)

Question 22

What was the procedure of Sperling’s study?

Answer 22

• 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)

Question 23

What are the strengths/weaknesses of Sperling’s study?

Answer 23

• 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)

Question 24

What are the strengths of the MSM?

Answer 24

• 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

Question 25

What are the weaknesses of the MSM?

Answer 25

• ‘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:

Question 26

What are the types of LTM?

Answer 26

• 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

Question 27

What are the differences between the different LTM?

Answer 27

• 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

Question 28

What are the strengths of the types of LTM?

Answer 28

• 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)

Question 29

What are the weaknesses of the types of LTM?

Answer 29

• 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

Question 30

What is the Working Memory Model?

Answer 30

• 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

Question 31

What is the central executive?

Answer 31

• 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

Question 32

What is the phonological loop?

Answer 32

• 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

Question 33

What is the visuo-spatial sketchpad?

Answer 33

• 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

Question 34

What is the episodic buffer?

Answer 34

• 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

Question 35

What was the procedure of Baddeley and Hitch’s (1976) study?

Answer 35

• 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

Question 36

What are the strengths of the WMM?

Answer 36

• 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

Question 37

What are the weaknesses of the WMM?

Answer 37

• 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