Memory

Memory

1. STM and LTM

   • STM
     • Capacity
       • Jacobs - digit span 9.3 for digits, 7.3 for letters
       • Miller - people remember about 7 items and 7 chunks
       • Evaluation
         • Cowan - 4 chunks is probably the limit
         • Simon - larger chunks means fewer recalled
         • Jacobs - 19 year olds have an 8.6 digit span whereas 8 year olds have a 6.6 digit span
     • Duration
       • Peterson and Peterson - used consonant syllables, prevented verbal rehearsal. STM lasted 18 seconds
       • Evaluation
         • Nairne et al - duration for STM 96 seconds
         • Consonant syllables not meaningful but some memory activities do involve such stimuli
         • Reitman - auditory tones to avoid displacement, led to longer duration of STM
     • Coding: Baddely - Acoustically
       • Evaluation
         • Wickens et al - STM sometimes uses a semantic code
         • Brandimote et al - STMs visually coded if verbal rehearsal prevented
   • LTM
     • Duration; Bahrick et al - after 48 years partcipants were 70% accurate in face recognition of classmates and 30% for names
     • Coding - Semantically
       • Evaluation
         • In Baddeley's study, LTM was tested by waiting 20 minutes which isn't really LTM
         • Frost - visual coding in LTM
         • Nelson and Rothbart - acoustic coding in LTM

2. The multi store model

   • Description
     • Sensory register - large capacity, short duration
     • Attention transfers information from sensory register to STM
     • Maintenance rehearsal eventually creates a LTM
     • Retrieval from LTM goes through STM
   • Evaluation
     • Strengths
       • Lab studies that support it
       • Brain scans - e.g. Beardsley linked STM to prefrontal cortext, Squire et al linked LTM to hippocampus
       • Case study of HM - linked formation of new LTMs to hippocampus (Scoville and Milner)
     • Limitations
       • MSM is too simple - LTM and STM are not unitary stores
       • LTM involves elaborative rather than just maintenance reharsal

3. The working memory model

   • Description
     • Central executive acts as 'attention' and allocates tasks to slave systems
     • Phonological loop preserves order of auditory information
       • Phonological store holds the words for the PL
       • Articulatory process performs maintenance rehearsal for PL, inner voice
     • Visuo-spatial sketchpad for planning and processing visual and/or spatial tasks
       • Visual cache for form and colour
       • Inner scribe for spatial relations
     • Episodic buffer records events as they happen, links to LTM
   • Evaluation
     • Strengths
       • Hitch and Baddeley - participants slower when doing dual tasks. Demonstrates CE
       • KF - damage to PL, problems with verbal material (Shallice and Warrington)
       • SC - damage to PL, unable to learn word pairs presented out loud (Trojano and Grossil)
       • LH - damage to spatial system (Farah et al)
     • Limitations
       • CE doesn't explain anything and it is more complex than it is represented, evidence from EVR (Eslinger and Damasio)
       • Brain damage evidence unreliable because trauma may cause problems

4. Types of LTM

   • Episodic memories - personal memories for events forming a sequence. They include details of context and emotion
   • Semantic memories - knowledge shared by everyone, abstract and concrete. They are acquired via episodic memories
   • Procedural memories - knowing how to do something. They become automatic through repetition and are disrupted if you think about them
   • Evaluation
     • Episodic memory associated with temporal lobe (including hippocampus) plus frontal lobe
     • Semantic memory associated with temporal lobe
     • Procedural memory association with cerebellum and basal ganlia and limbic system
     • HM - new procedural memories could be formed but not semantic and episodic ones
     • Evidence from amnesia patients - semantic memories can form independantly of episodic memories
     • Brain damage evidence unreliable because can't be certain that causal part of brain identified

5. Explanations for forgetting

   • Interference
     • Description
       • Retroactive interference - old info interferes with new info
       • Muller and Pilzecker - recall was less good if there was an interfering task
       • Proactive interference - new info interferes with old
       • Underwood - analysed many studies, the more lists learned, the lower percentage of recall
       • McGeoch and McDonald - learn lists of words + list of synonyms - 12% recall, learn list of words + list of digits - 37% recall. Similarity matters
       • Baddeley and Hitch - rugby players who played fewer games had better recall of teams played against (less interference)
     • Evaluation
       • Artificial research - words and nonsense syllables, and low motivation. Doesn't represent everyday memory
       • Limited to some situations of forgetting, where two sets of stimuli are quite similar
       • Ceraso - spontaneous recovery of recognition memory after interference suggests memories are available but not accessible
       • Real-world application - competing adverts reduce their effect because of interference, better to show three in one day (Danaher et al)
       • Individual differences - people with greater working memory span are less susceptible to proactive interference (Kane and Eagle)
   • Retrieval failure
     • Description
       • Encoding specificity principle - material present at encoding is present at retrieval (Tulving and Thomson)
       • Tulving and Pearlstone - category + word learned. Free recall was 40%, cued recall was 60%
       • Some cues are not meaningfully linked at encoding but also act as cues
       • Context-dependant forgetting: Abernety - recall best with same instructor in the same room
       • Context-dependant forgetting: Baddeley and Godden - recall best when inital context matched recall environment
       • State-dependant forgetting: Goodwin et al - recall best when initial state (drunk or sober) matched state at recall
     • Evaluation
       • High in validity - wealth of supporting research evidence both in lab and natural environments
       • Limited to some situations of forgetting, where two sets of stimuli are quite similar
       • Cues don't always work - not useful when learning meaningful material (Smith and Vela)
       • Encoding specificity is circular - it is not a causal relationship (Nairne) and cannot be tested (Baddeley)
       • Retrieval failure can explain interference effects so is the more important explanation of forgetting

6. Accuracy of Eyewitness testimony

   • Misleading information
   • Anxiety
   • The cognitive interview