Eyewitness Testimony

Memory

Watch this clip and answer the following questions 

http://www.youtube.com/watch?v=Nfz6e qaLrc4

Questions 1. 2.

3. 4.

5.

How many parked cars did you overtake before the roundabout? What coloured top was the person wearing who was talking into the passenger side? What was the registration no. of the white transit van? How many people were waiting to cross at the first set of traffic lights? What colour was the car that over took you?

Share your answers Are they all the same?  Was the pedestrian male or female? Can you be sure?  Did the wording of the questions influence your answers? 

Eyewitness Testimony Important aspect of criminal trials.  Often very influential.  Juries can decide based on eyewitness testimony alone. 

Reliable? Factors affecting? 

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How accurate do you think you would be in describing what you witnessed about the crash? What factors might influence your statement? Would being in a police station influence you? Would the police officers have any effect on you, say in their manner or in their questioning technique, even in the language they used? Would your impressions about police through television influence you?

Factors affecting testimony: 

Anxiety / Stress

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Reconstructive Memory

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Weapon Focus

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Leading Questions (Loftus and Palmer, 1974)

Anxiety/stress Clifford and Scott (1978) found that people who saw a film of a violent attack remembered fewer of the 40 items of information about the event than a control group who saw a less stressful version. As witnessing a real crime is probably more stressful than taking part in an experiment, memory accuracy may well be even more affected in real life.  However, Yuille and Cutshall (1986) found that witnesses of a gun shooting had remarkable memory. Even after 5 months and despite leading questions. 

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Chinese Whispers

Reconstructive Memory Bartlett, 1932 – recall subject to our perception based on our culture, norms and experience.  We fit memories into our understanding. This means memories can be distorted or unreliable.  'War of the Ghosts', Bartlett (1932) 

Weapon Focus As a witness you focus on the weapon making all other details secondary.  Loftus, 1987 

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Selective attention. Do you remember the clip with the gorilla?

Loftus and Palmer, 1974 Aim – to test if leading questions can distort eyewitness accounts.  M&P – Asked ppts (45 American students) to estimate the speed of vehicles after watching a clip of a car accident. A task ppl are generally poor at. The IV was the verb used in the question eg smashes, collided, contacted etc. 

Results

Conclusions A week later ppts were asked if they saw any glass at the scene. Despite there being none ppts in the ‘smashed’ condition were much more likely to say yes.  This suggests that memories are open to distortion by language and that confabulation can occur (addition of false details to an existing memory).  How might you use this knowledge if you are: 

a) A police officer

b) A lawyer?

Loftus and Zanni, 1975 Did you see the broken headlight? VS  Did you see a broken headlight? 

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Ppts asked ‘the’ were twice as likely to answer yes.

Evaluation Lacks ecological validity.  Consequences?  Closed questions. 

For you to research: 

Effect of individual differences on EWT:  Age  Occupation

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This work has led to the development of cognitive interview technique. Research more about this technique.