1 - Multi store model / coding, capacity, duration

What is the MSM (describe)

Describes how info flows through memory system

Coding definition

Info stored in memory in diff forms depending on memory store.

Process of converting info between diff forms = coding

Outline MSM model structure

Sensory register

• coding

• Capacity

• Duration

Coding - modality specific (depends on the sense)

• Eg iconic codes visual, echoing codes acoustic

Capacity - large

• due to millions of sensory receptors

Duration - Limited, less than half a second

• Sperling 1960’

Sperling 1960

1. Shown grid of letters and asked to recall them

2. Despite only seeing grid for short time, can recall a lot of it,

   shows high capacity nature of SR (high capacity)

3. Recall significantly declined as interval between seeing grid and recall increased. After a second it was virtually impossible

   shows fleeting nature (low duration)

STM

• coding

• Capacity

• Duration

Coding - acoustic

• baddeley 1966

Capacity

• Jacobs 1887

  digit span = 9.3

  Letter span = 7.3

• Miller 1956

  About 7 items +- 2

Duration - 18s

• Peterson + Peterson 1959

Jacob’s 1887

1. Start with 4 numbers, researcher adds a number and participant must recall the full list

2. Until participant can’t recall correctly

3. Digit span = 9.3

4. Letter span = 7.3

Strength of Jacob’s 1887

Study has been replicated in 2005 by Bopp and Verhaeghan

Tf increasing external validity

Miller 1956

Observations of everyday practice

• Noted that things come in 7s (eg 7 days of week), tf STM capacity = 7 items

• Chunking (grouping sets of digits/letters into chunks)

Miller limitation

Overestimated STM capacity

Nelson Cowan 2001 concluded capacity only 4+-1 chunks

Baddeley 1966

1. Given initial list

2. Gave second list. 4 diff types of lists to 4 diff groups

   Acoustically similar/dissimilar, Semantically similar/dissimilar

3. Recall original list

4. Recalling from STM - did worse acoustically similar words - tf STM coded acoustically

5. Recalling from LTM - did worse with semantically similar words - tf LTM coded semantically

Baddeley 1966 limitations

Low mundane realism = low ecological validity bc in highly controlled lab setting. Participants may not act ass they would irl

Use of artificial stimuli lowers external validity and real life application (comes up later)

Peterson + Peterson (1959)

1. Participants given consonant syllable (eg YCG)

2. given 3 digit number to count back from

3. Would be stopped at varying periods of time

4. After 18 seconds recall fell to 3%

   tf STM duration around 18s

Peterson + Peterson 1959 limitation

Use of artificial stimuli

Doesn’t reflect everyday life

Tf lacks external validity + real life application

LTM

• coding

• Capacity

• Duration

Coding - semantic

• Baddeley 1966

Capacity - unlimited

Duration - lifetime

• Bahrick 1975

Bahrick 1975

1. Participants of varying age + yearbook

2. Various tests = Photo recognition test, free recall test(recalling names)

3. Recall was better for younger but still present in older

   Shows LTM may last up to a lifetime for some material

Strength of Bahrick 1975

High external validity + real life application

Bc investigated meaningful memories

• Recall rates lower w/ meaningless pictures

More real estimate of of LTM duration

MSM strengths (2)

Support from case studies showing that LTM and STM are different

• Baddeley

• COUNTER = not everything is related to words (word lists = artificial stimuli) (eg faces, places)

  Tf not valid model of how memory works irl, tf limited application + lacks external validity

Real life application

• Prolonged rehearsal + active recall helps w/ revision

MSM limitations (1)

Evidence of more than 1 STM

• Shallice + Warrington Studied client w/ amnesia (KF)

  Could only recall info when read, not verbal said

  Tf only visual store was damaged

  Tf model must be more complicated than MSM