Document Type



Doctor of Philosophy (PhD)



First Advisor's Name

Stephen Charman

First Advisor's Committee Title

committee chair

Second Advisor's Name

Jacqueline Evans

Second Advisor's Committee Title

committee member

Third Advisor's Name

Deborah Goldfarb

Third Advisor's Committee Title

committee member

Fourth Advisor's Name

Amy Hyman-Gregory

Fourth Advisor's Committee Title

committee member


Eyewitness-identification, showups, decision-making, procedural safegaurd

Date of Defense



Showups—an identification procedure in which a single suspect is presented to an eyewitness—are considered to be highly suggestive by the U.S. Supreme Court and eyewitness researchers. Despite the suggestive nature of the procedure, showups are often utilized by law enforcement as a fast and easy means of either quickly arresting a suspect (if the witness makes an identification) or setting a suspect free (if the witness does not make an identification). Researchers have therefore begun examining procedural safeguards that might mitigate the suggestiveness of showups. To date, only the additional-opportunities instruction (AOI) has been developed as an easily implemented safeguard to address the suggestiveness of being presented a single suspect. This instruction has proved beneficial in the lab but has yet to replicate using more ecologically valid paradigms. It is argued that this failure to replicate is due to the instruction’s failure to undermine what we consider to be the leading factor behind the procedure’s suggestiveness in the real-world: the witness’s belief that police believe the suspect is guilty. Therefore, the present study had two research goals: 1) To test whether a new belief instruction aimed at undermining this belief improves showup identification outcomes; and 2) to test whether the AOI improves identification outcomes using a novel ecologically valid paradigm in which this belief exists. Using a 3 (belief instruction: control/suspect/bystander) X 2 (additional-opportunities instruction: given vs. not given) X 2 (target status: target-present vs. target-absent) between subjects design, participants (N = 1814) viewed a mock-crime they were led to believe was actual footage of a real crime and were presented with a showup identification procedure they believed to be part of an actual criminal investigation. As hypothesized, the AOI and suspect belief instructions had no impact on eyewitness decision-making; however, our novel bystander belief instruction led to a beneficial tradeoff between culprit and innocent suspect identifications as analyzed by logistic regression and receiver operator characteristic (ROC) analyses. Confidence-accuracy characteristic (CAC) analysis found no confidence-accuracy relationship.





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