3 factors that can affect eye witness memory:1. Stress, violence, attitudes2. time factors3. misremembering
-48% of all wrong convictions are due to misidentification
Retrieval stage factors:
- system variable influencing retrieval
- aids to recall/recognition:
- cognitive interview technique
- identity parades
Malpass and Devine (1981) - eye witness identifica
Aim: find if instructions given before an identity test can change result.
Method: researchers staged an act of violence in a lecture: students present asked to identify vandal from 1 of 2 line ups. half with vandal present and half with out vandal. half in each condition were given bias instructions and half not.Results: 100% in vandal present/bias gave + identification, 75% correct. unbias - gave 83% + identification - all correct.
Vandal absent/bias - 78% + identification - all false. unbias - 33% + false
Conclusions : Bias instructions leads to significantly more false identifications than neutral.
Pickel (1998) - 'weapon focus'
Aim: to test whether the weapon indicates threat, thus more arousal and weapon focus an if weapon focus is because it's unusual.
Method: participants watched a 2-minute video: man walks into a hair salon and receptionist gives him money.5 groups, man holding different things:1. nothing 2. scissors 3. hand gun 4. wallet 5. raw chicken. questionnaire: - first part on receptionist, second part on man (target). Asked to describe target and what he did, and identify him in line-up.
Results: no difference between high threat and low threat. However, high unusualness was a worse description than low, although no weapon focus in line-up.
Conclusion: it's not threat that creates weapon focus but unusualness.
Lindsay and wells (1985) - improving identificatio
Aim: is simultaneous line-up more suggestive than asking them to say whether each alternative is guilty?
Method: 5 staged thefts in view of students. 5 minutes later they were asked to identify theif from 6 photographs. half shown at same time, half asked to say whether each one was guilty or not, researchers held 12 even though they only showed 6, this is to stop the participants waiting. half shown with thief present, half not.
Results: Thief present - presentation didn't affect outcome: 58% simultaneous, other 50% correctly identified. However thief-absent, 43% simultaneous made false identifications, 17% for other
Conclusions: sequential line-up reduces false identification rate - thus making identification tests less suggestive.