Moderators of Lineup Administrator Expectancy Effects on Eyewitness Identification Accuracy

Cuny John Jay College Of Criminal Justice, New York NY

Investigators

Abstract

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5) Evidence of interpersonal expectancy effects in behavioral research led psychologists to suggest that lineup administrators' knowledge of a suspect's identity may play a role in mistaken identifications and to recommend double-blind lineup administration. However, the eyewitness identification task contains features that may constrain the influence of interpersonal expectancies. When the suspect closely resembles the perpetrator, expectancy effects may be suppressed because witnesses will choose the suspect without benefit of administrator cues; administrator influence may operate only when the suspect is less similar to the perpetrator. Similarly, the strength of the witness's memory may limit an administrator's influence to choose the suspect. These effects may be more likely when witnesses' criteria for choosing are low such as when certain system variables (biased instructions, simultaneous lineup presentation) are present. This research manipulates the similarity of the suspect to the perpetrator, memory strength (varying retention interval and exposure time), and the witness's criterion for making a choice from the lineup in three studies that simulate an eyewitness identification (i.e., a participant witnesses an event and the subsequently attempts an identification from a photo array). Using mathematical modeling techniques, the principal investigator examines the fit of the data from these studies to predictions made by the WITNESS model of eyewitness identification decision-making. The intellectual merit of these studies focuses on testing theorized constraints of administrator expectancy effects on eyewitness accuracy. The studies could prove transformative in that they could lead to a significant refinement of the leading theory of eyewitness memory, the WITNESS model. Moreover the findings have the potential for broad impact because they could inform police, many of whom have been resisting the recommendation to administer double-blind lineups, about when it is most important to expend resources to conduct seemingly more costly procedures. They will also provide information to assist investigators, expert witnesses, judges, and juries on eyewitness reliability.