Deffenbacher- meta anlysis of 18 studies showed that high levels of anxiety negatively affected accuracy of EWT.
However some studies show that aniexty can have positive impact.
Study byChristianson and Hubinette- questioned 58 real witnesses to a robbery. Those who had been threatend remembered more and were more accurate in recall than those who were onlookers as they were more emotionally aroused.
Yerkes- Dodson law- says that performance improves with increase in arousal up to a certain optimum point and then declines with futhre increase.
Weapon focus effect- in violent crimes, arousal may focus attention on central details eg a weapon. Loftus et al identified weapons focus effect. 2 conditions, one involving weapon the other not. Condition 1 (less violent) people were 49% accurate in identifying man. Condition 2 (more violent) people were 33% accurate. Suggests weapon may have distracted them.
Age differences in accuracy:
Parker and Carranza- compared ability of primary school and college students to identify a target individual. In photo identification, child more likely to choose somebody than adult although they were more likely to make errors.
Memon et al- studied acuracy of young and older eyewitnesses. When delay between incident and identification was short, was no difference in 2 groups. When delayed by 1 week, older witnesses less accurate.
Age of witness
The owen age bias:
Most studies shown older adults poorer at eyewitness memory. However, may result from stimuli typically used in these studies. Most studies used college students to correctly identify faces of similar aged targets. However, older adults where asked to identify college aged student targets. As a result, much of the work done on age differences in ERT has ignored possibility that participants may simply have better memory for faces of their own age.
Explaining the own age bias:
Findings from this research consistent with own race bias where people better at identifying people from their own ethinic group. The DIFFERENTIAL EXPERIENCE HYPOTHESIS suggests that the more contact we have with particular age group or ethnic group the better our memory would be for such individuals.