Theories of memory

• Human memory can most broadly be defined as the process by which we retain information about events that have happened in the past
• Coding can be defined as how information is stored in the various memory stores
• Features of short term memory:

  1. information that we process and recall straight away
  2. information we are currently aware of
  3. Information is taken in through our senses and the coding is changed to acoustic
  4. Rehearsing information can keep it in the STM for longer
  5. Limited between an average of 5-9 items - limited storage
  6. Duration between 18-30 seconds
• What is the capacity of the short term memory?

  7 (plus or minus 2) items
• what is the duration of the short term memory?

  18-30 seconds
• Features of the Long Term Memory:

  1. outside of our awareness
  2. can retrieve if needed
  3. coded for meaning - semantically
  4. potentially unlimited capacity
  5. duration is a potential lifetime
• What is the capacity of the long term memory?

  Potentially unlimited
• What is the duration of the long term memory?

  a potential lifetime
• Capacity can be defined as the amount of information held in the memory stores
• Duration can be defined as the length of time information can be held in the memory
• Coding can be defined as converting information from one format to another
• Information is stored in different formats depending on the store (STM/LTM)
• What did Baddeley do?

  Lab experiments with 4 conditions

  standardised

  replicable/reliable

  lacks ecological validity - artificial tasks

  lacks construct validity - tasks do not reflect/ are not reflective of real life tasks
• Acoustically = sounds
• Semantically = meaning
• What were the 4 conditions of Baddeley's lab experiment?

  1. acoustically similar (cat, can, cab)
  2. acoustically dissimilar (pit, few, cow)
  3. semantically similar (great, large, big)
  4. semantically dissimilar (good, huge, hot)
• What was the task in Baddeley's research?

  Learn the words and then recall as many as they could remember in order
• What were the results of Baddeley's study?

  STM recall - recall immediately - acoustically similar/ dissimilar

  LTM recall - recall after a break - semantically similar/ dissimilar
• What were the conclusions of Baddeley's research?

  STM coding = acoustic

  LTM coding = semantic
• Evaluation of Baddeley's study:

  1. Lab experiment - reliable, reproduceable, control over extraneous variables (e.g. same words, same time to recall/learn)
  2. Lacks ecological validity - in a lab setting - not real life setting (e.g. could have been done in a classroom) - shows demand characteristics
  3. Lacks construct validity - lists of random words rather than real life scenarios e.g. shopping lists
• Describe Miller's Research?

  observed everyday practice - noticed things come in 7s

  e.g. musical notes, days of week, 7 sins

  Therefore believed span of STM was 7 items +/- 2 (capacity)
• Evaluate Miller's research?

  Lack of research

  overestimated capacity of STM

  Nelson Cavan reviewed other research and concluded capacity is 4 +/- 1 chunks - towards the lower end of Miller's estimate

  5 items is more appropriate
• Describe Jacobs' Research?

  Research into how much information can be held in the STM at one time

  Read out 4 digits and increased the number every time until participants could not longer repeat it back to him

  He concluded that the final number they could recall correctly was their digit span

  On average 9.3 numbers and 7.3 letters immediately after being shown them
• Evaluate Jacobs' Research?

  Strength = it has been replicated

  HOWEVER - it is a very old study and early research often lacked controls e.g. some participants digit spans may have been underestimated if they were distracted during the test - confounding variables.

  BUT the findings were confirmed by better controlled studies (Bopp and Verhaeghen) who carried out a valid test of digit span in the STM
• Describe Peterson and Peterson's study?

  tested 24 undergrad students

  8 trials - in each trial given a consonant syllable to remember and a 3 digit number to count backwards from until told to stop.

  Each trial was stopped at a different time (e.g. 3,6,9,12,18 seconds

  Suggested STM had a short duration.
• Evaluate Peterson and Peterson's study?

  Meaningless stimuli in STM study

  The stimulus material was artificial although not completely irrelevant as we do sometimes have to remember fairly meaningless material (e.g. phone numbers)

  Even so, recalling consonant syllables does not reflect most everyday memory tasks - lacks external validity
• Describe Bahrick's research?

  Aim was to study the duration of the LTM

  Studied 392 American participants aged 17-74

  He obtained their high school year books and tested their recall of the people present in various ways

  1. photo recognition (50 photos)
  2. free recall - names

  He tested them after 15 years - photo recognition = 90%

  tested them after 48 years - 70% photo recall

  Free recall less accurate: 60% after 15 years and 30% after 48 years

  Shows that LTM may last a lifetime
• Evaluation of Bahrick's study: 1. Sample size was small 2. Sample was not representative of the population

  High external validity - researchers investigated meaningful memories

  When LTM studies conducted on meaningless pictures - recall rates lower

  Gives a more 'real' estimate of the duration of the LTM
• Whose research refutes Miller's?

  Nelson Cavan
• Whose research confirmed Jocobs'?

  Bopp and Verhaeghen
• How many trials did Peterson and Peterson do?

  8
• How many participants did Bahrick have?

  392 Americans 17-74
• What was the recall % after 15 years?

  photos - 90%

  free recall - 60%
• What was the recall % after 48 years?

  photo - 70%

  free recall - 30%
• Who developed the Multi-store Model?

  Atkinson and Shiffrin
• What did Atkinson and Shiffrin say?

  Memory is a process. The information we learn passes through a number of stores during the journey from STM to LTM
• Research on coding: information is stored in memory in different forms, depending on the memory store. The process of converting information between different forms is called coding