Memory

Joesph Jacobs

Study: Factors affecting capacity

Digit span study to work out the capacity of STM

Method: Researcher readds 4 digits aloud and participant has to recall them. Then 5, 6, 7 etc.

Findings: Number 9.3 Letters 7.3

Conclusion: STM has limited capacity 

Evaluation:

  • Long time ago, did not control confounding variables
  • Overestimated capacity- Cowan (2001) reviewed and concluded cap was 4 chunks
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Alan Baddeley

Study: Research on coding

Method: Gave different list of words to 4 groups of participants- acoustically similar, acoustically dissimilar, semantically similar, semantically dissimilar. They were asked to recall them immediately (STM) and 20 minutes after (LTM).

Results: STM- worse on acoustically similar. LTM- worse on semantically similar

Conclusion: STM- coded acoustically. LTM- coded semantically

Evaluation:

  • Artificial stimuli- generalising the findings, not meaningful
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Peterson & Peterson

Study: Duration of STM

Method: Tested 24 undergraduates, each taking part in 8 trials. On each trial the student was given a consonant syllable/trigram e.g. CFP And was given a 3 digit to count back from in 3s, to prevent rehearsal. Stop after 3,6,9,12 etc seconds (retention interval)

Results: Longer the interval, the less correct responses

Conclusion: STM has a very short duration unless we repeat it

Evaluation:

  • Artificial stimulus- lacks external validity
  • Memory trace simply disappears if not rehearsed (spontaneous decay)
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Harry Bahrick et. al

Study: Duration of LTM

Method: 17-74 year olds, using school yearbooks 1) Photo-recognition (matching) 2) Free recall of names

Results: 15 yrs 1) 90% 2) 60% 48 yrs 1) 70% 2) 30%

Conclusion: LTM can last a very long time

Evaluation:

  • Confounding variables- people could have practiced
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George Miller

Study: Span of memory & Everyday Chunking (capacity)

Method: Everyday observations e.g. 7 days in a week, 7 deadly sins

Findings: People can chunk in 7s- people can aslo recall 5 words as well as 5 letters

Conclusion: 7 + or - 2 items

Evaluation: 

  • Overestimate- Cowan concluded 4 chunks 
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Shallice & Warrington

Study: Patient KF with amnesia

Findings: STM for for digits was very poor when read aloud to him but recall was much better when read the digits himself 

Other studies as well as KF showed that there could be a STM for noises

Evaluation: People with brain damage do not represent the everyday mind, memory

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Craik & Watkins

Found that what really matters is the type of rehersal (not rehersal) 

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Tulving et. al

Study: Neuroimaging evidence

Method: Particants took part in various memory tasks while thier brains were scannned using a PET scanner

Findings: Episodic- prefrontal cortex (right), Semantic; prefrontal cortex (left), Procedural: Cerebellum and baal ganglia

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Bellellive et al

Study: demonstrate that episodic memories could be imporoved in older people who had a mild cognitive impairment

Findings: trained participants performed better than control group 

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Cohen & Squire

Disagree with Tulving's division of LTM- accept procedural is separate but belive semantic and episodic  are one store called declarative memory (conciously recalled) whereas procedural is non-declarative.

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Logie

Subdivided the Visuo-spatial sketchpad into:

Visual cache (storing visual data)

Inner Scribe (records arrangement of objects)

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Baddeley et al

Study: dual-task performance

Findings: showed that particpants had more difficulty doing two visual tasks than doing one visual one verbal

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Baddeley et al

Demonstrated that people find it more difficult to remember a long list of words rather than short words- word length effect

Because there is finite space for rehersal in articultaory process (about 2 secs)

Word length disappears if person is gven an articulatory suppression task- a repetitve task that ties up articulatory process e.g.doing a task whilst saying la la la- kept busy

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Braver et al

Method: gave participants tasks involving central exec whilst having brain scan

Findings: found greater activity in left prefrontal cortex & increased as task became harder 

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McGeoch & McDonald

Study: Retroactive interference

Method: Participants had to learn a list of words until they could remember them with 100% accuracy. Then had to learn a new list

G1: synonyms G2: antonyms G3: words unrelated to orignal G4: consonant syllables G5: 3 digit no.s G6: no new list

Findings: Synonyms prodcued recall 

Conclusion: Worst recall with similar words

Evaluation

  • Consistently researched- show both types are common
  • Not very real- artificial
  • Verys hort time in between- not real 
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Baddeley & Hitch

Study: Wanted to find if interference was better explanation than passing of time

Method: Asked rugby players to recall names of teams they had played that season, week by week. Some games may have been a few weeks ago (missed some)

Findings: Recall did not depend on time but how mnay games had been played 

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Tulving & Psotka

Study: Cues in interference

Method: Gave participants five lists of 24 words, organised into six categories

Findings: Recall was about 70% for first word list but fell as additional list was given. However, given cued recall test at the end- they were told the names of categories as a clue- rose to 70% again.

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Godden & Baddeley

Study: context-dependent forgetting

Method: Learned on land- recall on land, learned on land- recall underwater, learned underwater- recall on land, learn underwater- recall underwater

Findings: Recall was 40% lower when in non-matching conditions- external cues available ar learning were different to ones at recall, causing retrieval failure

Evaluation: 

  • Contexts have to be very different for an effect
  • Replicated using recognition test instead of recall- performance was the same in all foru situations- presence or absence of cues only affects memory when you test it in a certain way
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Carter & Cassaday

Study: State-dependent forgetting

Method: Gave anti-histamines to participants to make them drowsy, creating an internal physiological state different from normal state. Had to learn words:

Learn on drug- recall on drug, Learn on drug- recall when not on it, Learn off drug- recall on drug, Learn off drug- recall off drug

Findings: Worse recall when not the same 

Conclusion: When cues are not present, forgetting is worse

Evaluation:

  • Supporting evidence
  • Real life
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Loftus & Palmer

Study: Leading Questions

Method: Participants watched film clipsmof car accidents & were asked questions & one critical question about speed using words smashed, collided, bumped, contacted and hit

Findings: Mean estimate for 'smashed' was 40.5 mph whereas estimate for 'contacted' was 31.8 mph

Also did second experiment, people who heard smashed said there was breaking glass (there was not) so affected memory

Evaluation: 

  • Real events- helps to improve legal system
  • Only watched a clip- not real emotions, which can affect recall
  • Own age bias
  • Participants do not want to let researcher down (Zargosa & McCloskey)
  • Research studies do not have same consequences as real life (Foster et al)
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Gabbert et al

Study: Post-event discussion

Method: Pairs- ecah perosn watched the same video but from different angle and then discussed events

Findings: 71% reported events they did not see but picked up from discussion whereas 0% incorrect in control group

Conclusion: People go along with other witnesses- memoery conformity 

Evaluation:

  • Own age bias
  • Videos do not represent everyday life emotions
  • Anastasi & Rodes- 18-25 and 35-45 were more accurate than 55-78
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Johnson & Scott

Study: Anxiety has negative effect

Method: Lab study. Participants sat in waiting room and heard an argument. A man then walked out with grease on his hands carrying a pen (low anxiety). Another grouo heard the same argument but the smashing of glass and then the man walked out holding a paper knife covered in blood (high anxiety group)

Findings: Participants had to select man from 50 photos- LA: 49% HA: 33%- tunnel theory- focus on weapon (source of danger)

Evaluation: 

  • Does not represent real life
  • Weapon focus effect is unusual effect/suprise, not anxiety- Pickel conducted experiment with handgun, scissors, wallet, and raw chicken. Recall was worse with raw chicken 
  • Ethical issues
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Yuille & Cutshall

Study: Anxiety has a positive effeet on recall

Method: Real life study with shooting in a gun shop in Cnanda. 13/22 witnesses agreed to take part in study. Held interviews 4-5 months later and were compared to original police interviews (accuracy was determined on a 7 point scale). Also asked to report any emotional problesm they had experienced since.

Findings: Not much change in accuracy, only in terms of height, hair colour etc. High stress: 88% Low stress 75%

Evaluation: 

  • Field studies lack control
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