Factors Affecting Eyewitnesses (1)

Eyewitness task - video of burglary, burglar changes half way. Half of the participants were asked to remember, half weren't. Overall, 61% failed to notice the change (35% intentional, 88% incidental). 65% of those who had noticed the change correctly IDed both of the actors.

A man either pointed a gun at the cashier or handed them a cheque, Witnesses fixated more on the gun, and were less likely to correctly ID the perpetrator.

Meta-analysis - there is a decrease in correct perpetrator identification if a weapon is present.

First account used to explain the weapon focus effect. The presence of a weapon causes arousal and narrows the focus on to central cues, i.e. the gun, and less attention is given to peripheral cues.

Cue utilisation model - arousal restricts the focus of attention to the most immediate / central cues.

College students watched a videotaped event. There was either no weapon, a gun, or a stick of celery (unusal object). They later filled in a forced choice questionnaire. Participants were less likely to recall details about the perpetrator in the novel condition. Therefore, attentional effect is not specific to weapons.

Bell shaped curve of response / productivity as stress increases. The theory doesn't necessarily fit (Deffenbacher, 1983).

Stress may enhance memory for central details, but worsen it for peripheral details.

The Catastrophe model of anxiety and performance is now used to assess stress and performance / memory.

Field study - recall of witnesses of a violent crime, interviewed immediately and after 5 months. They were accurate in their recall with little change over the 5 months. The more stressed the witness was, the more detail they provided, although they tended to be closer / more involved in the crime.

Meta-analysis - heightened stress negatively impactedmemory. The accuracy of those with low anxiety was 54% and those with high anxiety was 42%.

As retention interval increases, the accuracy of the memory decreases.

Meta-analyses found a significant effect of delay on correct and incorrect perpetrator ID's.

Target present lineup used 1 week, 1 month, 3 months and 11 months after a live event. No difference in correct IDs from 1 wwek to 3 months (65%, 55%, 50%), although there was a dramatic decrease at 11 months (10%).

Varied retention interval and timing of first recall. The number of correct evet facts decayed, but errors remained constant over time. A single recall attempt prevented further decay in the total amount correctly recalled.

We all have a stereotype of a criminal, which can be problematic. Perceptions can be skewed and easily influenced by their motives. People sometimes see only what they want to see.

Eyewitnesses have better recall for schema-relevan information. They interpret ambiguous information in a schema-consistent way.

Misinformation effect or erroneous information can be provided through inadequate interviewing and memory contamination, e.g. the car crash study with leading questions.