Email rachel.zajac@otago.ac.nz
Tel +64 3 479 3988
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Eye-Witness Reliability
I work at the intersection of psychology and law. More specifically, I study the factors that influence people's ability to provide reliable evidence about events they have witnessed. Here are some of the questions that my students and I are currently trying to answer:
What effect does cross-examination have on children's testimony?
The majority of children testifying in adversarial criminal trials undergo cross-examination, during which their testimony is challenged by the opposing lawyer in an attempt to discredit it. By examining court transcripts and conducting experimental studies of children's responses to this type of questioning, we have repeatedly shown that most children make changes to their earlier testimony when cross-examined. Furthermore, these changes do not appear to be restricted to corrections of earlier mistakes. In fact, cross-examination-style questioning appears to exert an overall negative effect on children's accuracy. Our current research is aimed at finding out why this occurs, which children are most at risk, whether we can intervene to facilitate accuracy, and whether adults may also struggle to answer cross-examination questions accurately.
Can an eyewitness's evidence become contaminated through discussions with another witness to the same crime?
Crimes often involve more than one witness, and eyewitnesses are highly likely to discuss what they saw with each other before investigators arrive on the scene. Unfortunately, incorrect information provided by one eyewitness can contaminate another witness's evidence. We recently demonstrated that this effect extends well beyond witness's verbal reports about what they saw, by providing empirical evidence that co-witness misinformation about a perpetrator's appearance can increase the chances of mistaken identification from a photographic lineup. We are now trying to pinpoint the specific conditions under which this occurs.
How can we help children to avoid making mistaken identifications on photographic lineups?
There are numerous crimes in which a child may hold the only clue to the perpetrator's identity. Unfortunately, traditional procedures for eliciting eyewitness identification evidence can pose significant difficulty for children. In particular, children appear reluctant to reject photographic lineups, even when the perpetrator is not present. Given the devastating implications of mistaken identification in a legal context, it is crucial that researchers attempt to better understand children's lineup decisions and, where possible, intervene. We have recently developed the 'wildcard,' a simple technique to improve children's identification accuracy. We are now examining the conditions under which the wildcard is successful, and whether its success may extend to other groups of witnesses who are prone to error (eg, older adult witnesses).