Eliciting new information from eyewitnesses via repeated interviews: How does it impact accuracy and credibility? Amina Memon Royal Holloway, University of London Geralda Odinot University of Leiden David LaRooy University of Abertay

We know that..... Witnesses may be questioned on multiple occasions over lengthy delays (LaRooy Katz, Malloy & Lamb, 2010). That “different” information is often produced across repeat interviews raises concerns among legal professionals

Consistency and Accuracy: Impact on Witness Credibility Judges and Legal scholars deem witness consistency to be one of the most important measures of witness credibility Witness credibility is often attacked by highlighting inconsistencies in statements including the reporting of new previously unreported details. Self-contradiction is believed to be a result of a defect in memory or honesty of a witness Fisher, Brewer & Mitchell, 2009

In an applied setting We need to look carefully at what is recalled and not just amount (Koriat and Goldsmith, 1994) New information should not be viewed as inconsistent or contradictory or indicate that a witness is not credible or inaccurate (Gilbert & Fisher, 2006).

Lengthy delays The delays which occur during an investigation may compromise the quality of the evidence that can be obtained from a witness We could only sample short delays but we wanted to see if even a delay of 1 week would make a difference.

Research Questions How is eyewitness recall (quality and quantity) influenced over repeat interviews influenced by: Delay- forgetting increases over time so should a repeated interview be conducted as soon as possible? Interview (Cognitive or Structured) across repeat interviews?

Method 107 college students Video event of stalker who follows victim and enters her house One female interviewer fully trained in the Structured (SI) and Cognitive Interview (CI) Each witness was interviewed twice

Interviewer Training The interviewer underwent 2 day training in the Cognitive and Structured Interview methods with practice and feedback.

COGNITIVE Rapport & Ground Rules Report Everything Context Reinstatement Free Recall Question phase STRUCTURED Rapport & Ground Rules Free Recall Question phase

Immediate & 2 days Delayed for 7 & 9 days Condition 1CI-CI Condition 2SI-SI Condition 3CI-CI Condition 4SI-SI

Results Number of Correct Details in the first interview The number of NEW unique details across the two interviews 1. Interview type (CI or SI) 2. Interview timing (Early- Delayed for 7 days)

Note: most of these errors occurred during the questioning phase.

Results Next we will look to see if details (correct and incorrect) were consistently reported across the two interviews

Information gain from repeated testing Finally we looked at the cumulative recall across the two interviews We counted the repeated details only once and added any new previously unreported information.

Conclusions 1 Clear effects of early interview and repeated testing- gain in new correct details with small increase in errors CI advantage in correct details and consistent details- important for credibility CI small increase in reporting of erroneous detail- there were fewer errors in the free recall phase most arose in the questioning sequence.

Conclusions 2 Benefits of Repeated interviews-increase in the number of unique (cumulative) details Early interview advised but we need to examine the effects of longer delays

New Meta-analysis of the Cognitive Interview This research was funded by a European Union (FP6) grant