Chapter 17: Evaluating Eyewitness Testimony of Adults

The analysis demonstrates that eyewitness misidentification is the leading cause of wrongful convictions, requiring a systematic understanding of factors that compromise testimony accuracy. Witness characteristics prior to an event, including own-race bias, age effects, and familiarity, significantly predict identification performance, with individuals recognizing faces from their own demographic groups substantially better than out-group faces. During the criminal event itself, environmental conditions such as distance, lighting, and exposure duration directly affect memory encoding, while the presence of weapons causes attentional capture that redirects focus from the perpetrator's face. Intoxication and extreme stress further degrade memory quality, though moderate stress may enhance recall of central details. Post-event factors largely under law enforcement control introduce considerable bias and contamination through suggestive interviewing techniques, the memory-contaminating process of composite creation, biased lineup composition, exposure to misleading information, and repeated identification procedures that create source confusion. The chapter emphasizes that witness confidence, traditionally weighted heavily by courts, shows only modest correlation with accuracy and is easily manipulated through post-identification feedback, whereas response latency—the speed of identification—provides a more reliable indicator of accuracy. For forensic experts evaluating eyewitness cases, the chapter provides guidance on avoiding ultimate opinions about witness accuracy while educating fact-finders about the science of identification, analyzing whether procedures were equally likely to identify innocent and guilty suspects, and critically reviewing comprehensive case records including non-identifications that police frequently omit but that reveal important information about memory weakness and procedural flaws.