Improving accuracy of EWT: Cognitive interview

• What did Miller suggest?

  argued that most things come in 7s.

  On average we can recall 7 items(+-2)
• Limitations of Millers research

  May have overestimated the capacity of STM

  Cowan (2001) reviewer other research and concluded that capacity of stm was only about 4 chunksSuggests that the lower end of Millers estimate (5 chunks) is more appropriate than 7 chunks
• When did Jacobs do his study?(research on capacity)

  1887-the digital span test
• What was the letter average in Jacobs study?

  7.3
• What was the digital span average in Jacobs study?

  9.3
• What was Jacobs method?

  Researcher gives a number of digits and participants has to recall them in order.The researcher then increases the amount by 1 and the participant has to recall the sequence again, until they cannot remember.
• What was Peterson and petersons aim?

  to investigate the duration of STM
• What was Peterson and Petersons method?

  tested 24 students in 8 trials.On each trial, thestudent  was given a consant syllable eg YCG.They were then given a 3 digit number which they had to repeat backwards, to avoid rehearsal.

  On each trial they were told to stop after periods of time:3,6,9,12,15,18
• When did Peterson and Peterson conduct their study?

  1959
• List some weakness of Peterson and peterson study.

  -sample of 24-may have encountered Multi stori model before. Increasing demand characteristics

  -memory of psych students may eb different to those who aren't-cannot be generalised to population.

  lacks external validity- recalling consonant syllables does not reflect most everyday memory activity 
• List some strengths of peterson and petersons study.

  -took place in a lab 

  -high control of extraneous variables

  -scientfici-can be replicated and is reliable
• Findings of p and p

  3 seconds-90% recall

  18 seconds-10% recall
• What was p and ps method?

  tested 24 students in 8 trials.On each trial, thestudent  was given a consant syllable eg YCG.They were then given a 3 digit number which they had to repeat backwards, to avoid rehearsal.

  On each trial they were told to stop after periods of time:3,6,9,12,15,18
• What was Bahricks aim?

  investigate the duration of LTM
• When did Bahrick do his study?

  1975
• Weaknesses of Bahricks study

  -lacks population validity- only focuses on one high school. 

  -unable to generalise to other countries (UK,europe) as they are all american students.

  -may be rehearsal as some may still be in touch with ex classmates.
• Strengths of Bahrick study

  high external validity

  real life meaningful memories studied

  recall rates were lower with artificial material(Shepard 1967)
• Bahrick Findings?

  15 years  after graduation-90% accurate for photo recognition

  48 years-70% accurate.

  free recall

  60% after 15

  30% after 48
• Bahrick Method?

  392 uni graduates between 17-74 

  Tested in 2 ways 

  1. photo recognition- 50 yearbooks and recalling names

  2.free recall-names in graduating class
• Baddeley aim?

  establish whether STM and LTM encode information in different ways
• When did Baddeley do his study?


  1966
• Baddeley findings

  -Acoustically simialr and sementically similar were harder to recall
• STM encodes information acoustically, while LTM encodes information semantically.
• Limitations of Baddeley include:

  Artificial stimuli- word lists had no personal meaning. Baddeleys findings may not tell us much about coding in different kinds of memory tasks. 

  -sample included 72 participants not representative of population and limits generalisability.

  lab study-low ecological validity-unlikely procedure in real life
• Strengths of Baddeley include:

  -High reliability-study was standardised

  -interference tasks(20 minute delay) to make sure he was actually measuring LTM memories

  -identified clear difference between 2 memory stores, lead to msm trengths of Baddeley

   
• Baddeleys method was as follows:

  -Gave participants 4 trials at learning the order of a list of words

  -Used 20 minutes delay with interference activities and asked the participants to recall.

  72 participants through oppurtunity sampling and were randomly allocated to 4 groups.

  slideshow of 10 words

  3 seconds per word.

  Groups were-

  1.Accoustically similar(cap,hat,sack)

  2.dessimilar(led,cow,dad)

  3.semantically similar(big,large,huge)

  4.semantically dissimilar(hot,pen,man)
• What is a cognitive interview?

  a method of interviewing eyewitnesses to help them retrieve more accurate memories.It involves using techniques based on evidence-based psychological knolwedge.
• Give some weaknesses of Ci 

   

  counterpoint of Kroekhen- increase in inaccurate info, more detailed recall increases the chances of making mistakes? quality over quantity?

  Milne and Bull(2002)-found that the techniques used on their own produced more info than the standard police interview.

  some components better than others-combiantion of reinstate context and recall everything produced best recall.

  (creates doubts on credibility)

  time consuming- requires specialist training and many forces do not have resources to provide more than a few hours(Kebbell and Wagstaff 1997)
• Give some strenghts of CI

  supporting effectiveness-Meta analysis by Konkhen et al.

  combined data from 55 studies comparing CI AND ECI with standard police interview.

  Ci-average 41% increase in accurate info compared to standard.

  only 4 studies showed no difference.

  Fisher et al(1990)- witnesses reported greater detail in their accounts of the crime when american detectives had been trained to use the technique.

   

  -more structured
• What is the enhanced cognitive interview?

  advanced version of CI, which adds more social aspects to the setting and procedure.Including relinquishing and establishing of eye contact, reducing eyewitness anxiety, minimising distractionsn and getting the witness to speak slowly.
• Why is the technique of 'changing the perspective' done in cognitive interviews?

  To disrupt the effects of expectations and also the effect of schema on recall.

  Schema for a particular setting-eg going to a shop) generates expectations of what would have happened-schema recalled rather than actual event.
• Why is the technique of 'reversing the order' done in cognitive interviews?

  to prevent people reporting their expectations of how the event must have happened,rather than reporting actual events.

  Also prevents dishonesty-more difficult to reverse order if lying.
• What are the four main techniques?

  1.Report everything-may trigger other important memories.

  2.Reinstate the context-witness should return to the original crime scene 'in their mind' and imagine the env,(such as what the weather was like, what they could see).

  3.Reverse the order-events should be recalled in a different order from the original sequence.

  4.Change perspective-witnesses should recall the incident from other's perspective.
• What did Fisher and Geiselman argue about eyewitness testimony?

  Could be improved if the police used techniques when interviewing witnesses.