Cognitive - Eyewitness Testimony - Anxiety

Weapon Focus effect - Arousal may focus the witness on more central details of the attack (e.g. the weapon) than the more peripheral details.

Johnson and Scott (1976) 

Procedure

- Used two conditions - one with a weapon and one without.
- Participants heard a discussion in another room.
- Condition 1: Man emerged with a pen and grease on his hands.
  Condition 2: Man emerged with a knife covered in blood.
- Participants asked to identify man from 50 photos.

Findings

- Participants in condition 1 were 49% accurate.
- Participants in condition 2 were 33% accurate.

Evaluation

+ Field experiment - easily replicated - high reliability.
+ Independent groups - no order effects.

- Era dependent and outdated.
- Protection from harm - participants could be distressed.
- High ecological validity - reflects natural behaviour.
- Deception.
- Can't establish cause and effect.
- Independent groups - participant variables.

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Christianson and Hubinette (1993) 

Procedure

- Questioned 110 witnesses who had seen 22 genuine bank robberies. 

- Some were onlookers, some employees.

Findings

- Victims more accurate in recall and remembered more details about robbers than bystanders even after 15 months later. 

- People (especially victims) are good at remembering highly stressful events if they occur in real life rather than in the artificial surroundings of the laboratory. 

Evaluation

+ Natural experiment - reflects real behaviour - high ecological and external validity.

- Social desirability bias. 

- Low internal validity. 

- Can't be replicated - low reliability.

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Yuille and Cutshall (1986) 

Procedure

- Interviewed 13 witnesses to real-life shooting. 

Findings

- Witnesses gave accurate accounts months later. 

- Those closest to event recalled more detail.

- Most distressed were the most accurate 5 months later. 

- Heightened arousal enhanced accuracy

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Defenbacher et al (2004) 

Procedure

- Meta-analysis of 18 studies looking at anxiety on accuracy of recall. 

Findings

- High levels of stress negatively impacted on the accuracy of eyewitness memory. However, some studies found it may enhance accuracy. 

- Yerkes-Dodosn law established - curvilinear relationship between arousal and accuracy.