Cognitive Flashcards
Memory
The process by which we retain info about events that have happened in the past
STM Capacity
Very limited capacity 7 +/- 2 - Miller’s magic 7
LTM Capacity
Potentially unlimited = hard to measure
Millers Magic 7
Tested capacity of STM & found = 7 +/- 2 meaning in every day life we may only remember 7 numbers / letters
Digit Span Test
Jacob’s 1887
Given number of digits & Ptp asked to remember in order - inc by 1 digit each time until can no longer remember in order
= 443 females (8-19) North London collegiate school - mean digit span = 9.3 & letter span = 7.3
Strengths of Miller’s Magic 7
Theory is based on & supported by research e.g., Jacob’s
J’s research = based on systematic & replicable procedure - Digit span shown as reliable & valid by others
Weaknesses of Miller’s Magic 7
J’s research done in 1800s may not = well controlled - could be affected by confounding variables
M’s theory that ppl can remember as many chunks as letters = disproved - shorter span for longer chunks - Simon 1974
Cowan 2001 reviewed a variety of studies into STM & concluded it is likely to be limited to about 4 chunks
Some researchers have looked at STM capacity for visual info & 4 items = limit
M’s work based on others work may have made mistakes
Strengths of Jacob’s Study
Based on systematic & replicable procedure - shown to be r & v by others
In controlled environment & large num of ptps = gen to large group of ppl
Created objectifiable method
Weaknesses of Jacob’s study
May = IDs
Cannot be gen to rest of society only = young girls
May not have been well controlled like today - confounding variables
STM Duration
Limited 18-30 seconds
Most ppl keep info longer by rehearsing- repeating keeps memory active
LTM Duration
Unlimited theoretically whole life
Peterson & Peterson 1959 Procedure
Investigated probability of recalling info when rehearsal = prevented
Lab exper Repeated Measures 24 intro psych students at Indiana Uni
Ptp given a 3 letter trigram & a number to count back from in 3s / 4s when red light appeared recall = 3-18s
Peterson & Peterson 1959 Findings
As delay inc recall ability decreased
Verbal repetition prevents rehearsal from taking place so items being learnt = lost - lasted approx 18 secs
Peterson & Peterson 1959 Criticisms
Nonsense trigrams in a lab = low eco val
Relates to 1 aspect of memory & may not apply to all aspects (semantic, episodic & procedural)
Students aren’t like everyone else - clever & younger
Psych students may try to guess the aim may change behav - DCs
Single blind & double blind can combat
Research into STM Duration
STM = short duration - P&P suped by Sebrechts (1989) - Ptps asked to unexpectedly recall 3 words did well if recall = immediate after 4 = almost 0 - sups limited duration w/o rehearsal / processing
M recent research shows STM duration is not as P&P thought - Naire (1999) thinks can = 96 secs
Research into STM Duration Criticisms
In Naire’s study ptps were asked to recall the same items across trials earlier studies used dif items could lead to interference dec recall
Info remains in STM for quite a while unless overwritten / replaced
Bahrick Procedure
Aimed to investigate VLTM in a natural setting w/ personal significance - comp verbal & visual
Sample - 400 Ptp 17-74 various tests - year book used to ensure accuracy
1. Free recall names in grad class 2. Photo Rec 50 photos from their class 3. Name Rec x school friends
Bahrick Findings
Tested w/in 15 yrs = approx 90% accurate faces & names
After 48 = 80% for name & 70% for face
Free recall less good 15 yrs = 60% 48 = 30% - LTM lasts longer if visual than verbal as older free recall dec = harder to retrieve w/o stimulus
Bahrick Conclusions
Evidence of VLTM - some loss - verbal almost as good as visual - recog better than recall - need stimulating
Bahrick Criticisms
Could have looked at yearbook recently - could recall m info - may have met friends recently
Some may know m / some old have mem probs
Eco val not lab exper
Encoding
Initial learning of info = how info from sensory input is changed into a form it can be stored
E.g., a word seen may be stored is encoded into a sound / meaning
1st stage of process of memory involves processing info not same in LTM & STM
Visual Encoding
Images
Elaborative Encoding
Relating to prior knowledge
Tactile Encoding
Touch