Factors Affecting Eyewitnesses (1)


Davies & Hines (2007)

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.

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Loftus, Loftus & Messo (1987)

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.

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Steblay (1992)

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

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Arousal Hypothesis

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.

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Easterbrook (1995)

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

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Mitchell, Livosky & Mather (1998)

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.

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Yerkes-Dodson Law (1908)

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

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Christianson (1992)

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

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Hardy & Parfitt (1991)

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

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Yuille & Cutshall (1986)

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.

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Deffenbacher (2004)

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

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Ebbinghaus' Forgetting Function

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

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Steblay, Dysart, Fulero & Lindsay (2001), (2003);

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

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Shepherd (1983)

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%).

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Ebbesen & Rienick (1998)

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.

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Hastorf & Cantril (1954)

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.

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Tuckey & Bewer (2003a;b)

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

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Loftus & Palmer (1974)

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

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