Cautioning jurors regarding co-witness discussion: the impact of judicial warnings

Abstract

This study examined how a judge's warning regarding the impact of co-witness discussion on eyewitness memory might affect juror decision making. 80 participants acting as jurors read a criminal trial transcript in which the major piece of prosecution evidence was the testimony of two eyewitnesses. Participants heard that there were some inconsistencies between the initial statements made by the two eyewitnesses at the scene of the crime, but that later one of the eyewitnesses amended her account so that it matched that of her co-witness. Half heard an admission by the eyewitnesses that they discussed the event after making their initial statements, while the others heard that the eyewitnesses denied any discussion had occurred. The trial judge then gave either a general warning about eyewitness accuracy or a specific warning about relying on eyewitness agreement as an indicator of accuracy when eyewitness discussion had occurred. After reading the transcript, each participant gave his or her individual ratings regarding verdict, belief in the eyewitnesses and reliance on various witnessing factors. The specific warning enhanced juror sensitivity to eyewitness discussion when assessing the evidence of the inconsistent eyewitness, but not the consistent eyewitness. There was no evidence that the warning resulted in scepticism.

Keywords:

• memory conformity
• eyewitness
• expert evidence
• judicial warning
• jury

Acknowledgement

This research was supported by an Australian Research Council Linkage Grant (LP0989719).

Notes

1. When we exclude from this analysis participants who were unable to remember whether discussion took place this difference is significant (t=2.0; df=34; p=0.05). Exclusion of these participants does not otherwise change the pattern of the results.