memory

• Multi-store model of memory (MSM)

  Atkinson and Shiffrin: A representation of how memory works in terms of three stores:

  1. Sensory register

  2. STM

  3. LTM

  
  

  Describes how information is transferred from one store to another, how it is remembered and how it is forgotten
• Capacity


  How much can be held in memory
• Duration


  How long a memory lasts before it is unavailable
• Coding


  The way information is changed so that it can be stored in memory
• Sensory register


  A temporary storage device for holding sensory memories
• Iconic memory store in the sensory register

  Visual information, coded visually
• Echoic memory store in the sensory register

  Auditory information, coded acoustically
• Duration of sensory register

  Less than half a second
• Capacity of sensory register

  Very high
• When is information passed from the sensory register to STM?

  When we pay attention to it
• Short term memory (STM)


  Memory for immediate events
• Capacity of STM


  7 +/- 2 items
• + Supporting evidence for capacity of STM

  Jacobs: Ps were read lists of words/numbers that thy had to recall immediately after the presentation. The length of the words or numbers was increased until Ps could only accurately recall the information, in the correct order, 50% of the time.

  
  

  Findings: Ps could recall 9 numbers but only 5 letters.

  
  

  Miller: We can remember 5 words and 5 letters by chunking/grouping sets of digits or letters into units.
• - The capacity of STM is not the same for everyone


  It has been shown to increase between the ages of 8 and 19. Miller and Jacobs both suggested that capacity falls between 5 and 9 for everyone, which may not be the case.
• Duration of STM


  Around 18 seconds
• + Supporting evidence for duration of STM

  Peterson and Peterson: 24 university students were tested over 8 trials. On each trial, P was given a consonant syllable and a three-digit number. They were asked to recall the consonant syllable after a retention interval, during which they had to count backwards from their three-digit number.

  
  

  Findings: Ps were 90% correct after 3 seconds, 20% correct after 9 seconds, and 2% correct after 18 seconds
• - Unrepresentative sample in Peterson and Peterson's study


  Used only university students, meaning it is difficult to generalise the findings

  
  

  Students use their memory more actively than adults meaning their memory is likely to be more accurate than others.
• - Peterson and Peterson's findings may show the effect of displacement rather than decay


  Decay is where information is forgotten, where as displacement is where information has been overridden.

  
  

  These memories (consonant syllable) had been overridden by something else (three-digit number) meaning their conclusions may be inaccurate.
• Coding of STM


  Acoustically
• + Supporting evidence for coding of STM

  Baddeley: Ps heard words then had to recall them in the correct order.

  
  

  Findings: When they had to recall them immediately after hearing it they tended to do worse with acoustically similar words, suggesting STM is coded acoustically.
• - Baddeley used artificial stimuli


  The word list had no personal meaning to Ps. The results may be inaccurate, therefore, meaning we should be careful about generalising the results to all memory.

  
  

  When processing more meaningful information (e.g. a shopping list), people may use semantic coding even for STM tasks.
• How is information transferred for STM to LTM?

  Maintenance rehearsal
• Long term memory (LTM)

  Memory for events that have happened in the past
• Capacity of LTM


  Unlimited

  
  

  The main constraint is accessibility not availability
• Duration of LTM


  Almost a lifetime
• + Supporting evidence for duration of LTM

  Bahrick et al: 392 graduates were shown photos from their high-school yearbook.

  
  

  Recognition group: For each photo Ps were given a group of names and asked to select the name that matched the person in the photo.

  
  

  Recall group: Ps were simply asked to name the people in the photos.

  
  

  Findings (recognition group): 90% were correct in the recognition group after 14 years of graduating, 60% were correct in after 47 years of graduating.

  
  

  Findings (recall group): 60% were correct after 7 years and less than 20% were accurate after 47 years.

  
  

  Conclusion: People can remember certain types of information for almost a lifetime. LTM appears to be better when measured by recognition tests than by recall tests.
• + Bahrick's study used meaningful stimulus


  High-school yearbooks are meaningful stimuli.

  
  

  This tests peoples memories from their own lives so it had high ecological validity.
• Coding of LTM


  Semantic
• + Supporting evidence for coding of LTM

  Baddeley: Ps heard words then had to recall them in the correct order.

  
  

  Findings: When they had to recall them after an interval of 20 minutes, they tended to do worse with semantically similar words, suggesting LTM is coded semantically.
• - Baddeley may not have tested LTM


  It is questionable as to whether testing after 20 minutes is actually testing LTM.
• + Supporting evidence for MSM from case studies


  Clive Wearing and HM both suffered from anterograde amnesia. They both had severe damage to areas of their brains that contain the hippocampus (part of the brain in charge of memory).

  
  

  They both lost the ability to form new LTM, but had normally functioning STM. This demonstrates how STM and LTM are completely separate entities.

  
  

  - Case studies cannot be generalised to everyone.
• + Supporting evidence for MSM from brain scans


  Beardsley: Prefrontal cortex is active during STM tasks but not LTM tasks.

  
  

  Squire et al: Hippocampus is active during LTM tasks but not STM tasks.
• - Maintenance rehearsal may not be the reason information is transferred from STM to LTM


  Craik and Watkins: Elaborative rehearsal is required for long-term storage. This occurs when you link the information to your existing knowledge, or think about what something means.

  
  

  Craik and Tulving: Ps were given lists of nouns and asked a question that involved shallow or deep processing.

  1. Is the word printed in capital letters? (shallow processing)

  2. Does the word fit in a sentence? (deep processing)

  Ps remembered more words that were deeply processed than those that involved shallow processing.
• Cognitive interview


  A method of interviewing eyewitnesses to help them retrieve more accurate memories
• 4 techniques used in cognitive interview

  1. Report everything

  2. Mental reinstatement of the context

  3. Reverse the order

  4. Change perspective
• Report everything


  Encouraged to include every single detail, no matter how irrelevant it may seem
• Mental reinstatement of context


  Returning to original crime scene in their minds, based upon context-dependent forgetting
• Reverse the order


  Events should be recalled in a different order from the original sequence.

  
  

  This is done to prevent witnesses reporting their expectations of the event.
• Change perspective


  Witnesses should recall the incident from other people's perspective.

  
  

  This is done to disrupt the effect of expectations and also the effect of schema on recall.
• Enhanced cognitive interview


  Fisher et al developed some additional elements of the cognitive interview which focus on the social dynamic of the interview. These include:

  1. When to establish eye contact

  2. How to reduce anxiety felt by eyewitness

  3. Minimising distractions

  4. Getting the witness to speak slowly