The scientific eyewitness literature borrows from both cognitive psychology and social psychology in order to account for many of the findings. Cognitive psychologists tend to study the roles of attention, perception, memory, and interference as factors affecting the accuracy of eyewitness testimony whereas social psychologists tend to study the roles of witness beliefs and social influences on eyewitness testimony. Commonly, however, the phenomena observed in the experiments are both cognitive and social. Eyewitness testimony research includes studies of the accuracy of witness s first-hand reports of memory for objects, actions, time, distance, and people. Numerous general conclusions about the accuracy of eyewitness identifications can be derived from staged-crime experiments.
False identifications are surprisingly common in staged crime experiments.
When the perpetrator is in the lineup, the perpetrator is the person most commonly identified. When the actual perpetrator is not in the lineup, eyewitnesses often have great difficulty recognizing the perpetrator s absence. When the perpetrator is not in the lineup, there is still someone who looks more like the perpetrator than do the other lineup members and eyewitnesses tend to identify that person. Failure to give this instruction is known as an instruction-biased lineup. Importantly, giving the warning does not have an appreciable effect on the rate of identifications of the culprit when the culprit is present, but only serves to protect innocent lineup members when the culprit is absent.