Psychologists occasionally testify about the factors that influence eyewitness identification accuracy in criminal cases in which eyewitness identification is a pivotal issue. Considerable research has addressed the need for this testimony and its impact on the jury. Typically, the expert witness is trained in cognitive or social psychology and has published scholarly work about eyewitness identification accuracy. Most often, the expert witness is offered by the attorney for the defendant. In such cases, the expert undergoes “direct examination” by the defense attorney and “crossexamination” by the prosecuting attorney.

The purpose of this form of expert testimony is to educate the jury about the factors that are known from research to influence the likelihood of false identification. The content of the expert testimony typically focuses on issues ...