Factors that influence the accuracy of EWT Flashcards
What are the studies on anxiety and eyewitness testimony?
Deffenbacher et al (2004) did a meta-analysis on 18 studies after looking at 21 and found a negative relationship between anxiety and eye witness testimony.
However, Christianson and Hubinette (1993) asked 58 real witnesses and found that those threatened with a gun were more accurate in their recall, than less aroused witnesses. This continued to be true 15 months later
What is used to explain the contradiction in the studies on anxiety?
Deffenbacher suggested the Yerkes-Dodson law (1908) could explain this contradiction. This law states that a moderate amount of arousal causes increased performance, but excessive amounts become detrimental.
What is the weapon focus effect?
The effect of a person concentrating on more central details of a violent crime, such as the weapon used then the peripheral details, such as the persons face.
What research is there on the weapon focus effect?
Johnson and Scott (1976) showed two conditions. The first was a discussion in a adjoining room, with a man leaving with a pen and grease on his hands. The second was a discussion the same, except the discussion was harsher and the man leaving wielded a bloody paperknife covered in blood. When asked to identify the man from 50 photos condition 1 was 49% accurate while the second was 33%. Showing that the weapon may have distracted them.
Steblay (1992) did a meta-analysis and found the presence of a weapon reduces the accuracy of the witnesses’s identification of the wielder.
Loftus et al (1987) monitored witnesses eye movements and found that their eyes were drawn to the weapon and away from peripheral details, such as the face.
What research has been done on the age of witnesses?
Parker and Carranza (1989) asked children and college students to correctly identify a target individual out of a slide sequence of a mock crime. The children had a higher rate of choosing but were less accurate than the college students.
Yarmey (1993) asked 651 adults to recall the physical characteristics of a young women they had spoken to for 15 seconds 2 minutes ago. Young and Middle aged people were more confident and accurate than Older people.
Memon et al (2003) found that after a 35 minute delay they was no difference in the identification accuracy of younger and older eyewitnesses. But if the delay was a week long the older witnesses were less accurate.
Deffenbacher et al (2004) found that heightened stress did not have a debilitating effect on eyewitnesses.
How are some of the age studies explained?
Anastasi and Rhodes (2006) showed participants of varying ages were shown 24 faces of varying ages and asked to rate them for attractiveness. This was followed by a filler activity. Then they were shown 48 pictures, 24 of which they’d already seen and asked to identify which were repeated. They found that the younger and middle-aged were most accurate, but more interestingly each age group was best at identifying its own age group.
Brigham and Malpass (1985) would explain this with the differential experience hypothesis - we have better memories of groups we spend more time with.
The perceptual learning hypothesis would say we process the faces better because we spend more time with similar ones.
