Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Psychology

Program Name/Specialization

Social Psychology

Faculty/School

Faculty of Arts

First Advisor

Judy Eaton

Advisor Role

Thesis Supervisor

Abstract

There is limited research examining the possibility of a temporary appearance change (e.g. a black eye) between exposure to a perpetrator at the time of a crime and later identification attempts by eyewitnesses. Across two experimental studies, this research examines how eyewitness identification decisions are impacted by an appearance change and how lineup procedures can influence eyewitness accuracy. Study 1 examined how a transient facial feature, a black eye, affects the accuracy of eyewitnesses’ identification decisions, while manipulating the severity of the black eye (prominent bruising, faded bruising, no bruising). Participants (N=403) were exposed to a 43-second mock crime video in which the perpetrator had a visible black eye and were later shown either a six-person simultaneous lineup or a six-person sequential lineup with either the target-present or target-absent. The appearance change was either replicated or removed among all lineup members dependent on the lineup condition. Study 2 examined how the presence of an appearance change at the time of a crime affects eyewitness accuracy, and whether eyewitness accuracy is further affected by the availability of partial face information. Participants (N=478) were exposed to a mock crime video where the perpetrator had a visible black eye and were later presented with a six-person sequential lineup with either the target-present or absent. The appearance change was either replicated or removed among all lineup members dependent on the lineup condition.

Findings from Study 1 suggested that lineup formation does have a significant effect on eyewitness accuracy in target present lineup conditions, with sequential lineups yielding a higher rate of eyewitness accuracy. However, no significant differences were found regarding replication and removal of the appearance change. This suggests that the presence of the appearance did not significantly affect eyewitness accuracy. Findings from Study 2 indicate that a temporary appearance change does have a significant effect on eyewitness accuracy when there is only partial face information available to the eyewitness. In the target-present conditions replication of the appearance change (prominent black eye condition) resulted in higher eyewitness accuracy, whereas, in the target-absent conditions, removal of the appearance change (no black eye condition) yielded higher eyewitness accuracy. Additionally, participants who were exposed to the upper face (forehead, eyes, nose) condition yielded higher accuracy rates than those who were exposed only to the eye region (eyes, eyebrows) conditions.

Overall, these findings indicate that temporary appearance changes seem to have less of an effect on eyewitness accuracy when full facial information is available to the witness; however, when only partial face information is available, the appearance change becomes increasingly more influential on eyewitness accuracy. This research can help inform how law enforcement officials should carry out eyewitness lineup procedures when it is reported that a temporary appearance change was present at the time of the crime and/or when restricted facial information is available to the witness, such as if a perpetrator was wearing a mask.

Convocation Year

2026

Convocation Season

Fall

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