Leading social science researchers identify two main categories of variables affecting eyewitness identification: estimator variables and system variables.
Estimator variables are those that cannot be controlled by the criminal justice system. They include simple factors like the lighting when the crime took place or the distance from which the witness saw the perpetrator. Estimator variables also include more complex factors, including race (identifications have proven to be less accurate when witnesses are identifying perpetrators of a different race), the presence of a weapon during a crime, and the degree of stress or trauma a witness experienced while seeing the perpetrator.
System variables are those that the criminal justice system can and should control. They include all of the ways that law enforcement agencies retrieve and record witness memory, such as lineups, photo arrays, and other identification procedures. System variables that substantially impact the accuracy of identifications include the type of lineup used, the selection of “fillers” (or members of a lineup or photo array who are not the actual suspect), blind administration, instructions to witnesses before identification procedures, administration of lineups or photo arrays, and communication with witnesses after they make an identification.
Several implementable procedures have been shown to significantly decrease the number of misidentifications by controlling system variables and reducing the chances of producing a biased result.
The Innocence Project recommends that all jurisdictions immediately adopt the following policies:
- Blind administration
Problem — Numerous studies show that lineup administrators, when they know who the suspect is, can strongly bias the eyewitnesses. Usually unintentional, an administrator may make a suggestive statement or supply an unconscious gesture or facial expression that provides misleading feedback to the witness.Reform Solution — Implementing blind administration, where the officer administering the lineup is unaware of who the suspect is, can prevent these unconscious actions and significantly reduce the likelihood of misidentification. For law enforcement agencies with limited manpower or in situations where all members of a particular law enforcement agency are aware of the identity of the suspect, a lineup can be administered in a “blinded” fashion, whereby the administrator – who knows the suspect’s identity – is shielded from observing the lineup members being viewed by the eyewitness and therefore cannot influence the selection.
- Lineup composition
Problem — Lineup composition is crucial for a fair lineup , as a biased lineup can cause an innocent suspect to stand out and thus increase the likelihood of a false identification.Example – On July 17, 1982, a young woman was raped by a black man whom she said was a total stranger. After she reported the crime, a police officer singled out Marvin Anderson as a suspect because the perpetrator had told the victim that he “had a white girl,” and Marvin Anderson was the only black man the officer knew who lived with a white woman. Because Anderson had no criminal record, the officer went to Anderson’s employer and obtained a color employment photo identification card. The victim was shown the color identification card, along with six black-and-white mug shots, and identified Anderson as her assailant.He was only eighteen years old when he was convicted of robbery, sodomy, abduction, and rape. Anderson was released under parole fifteen years later, but took another four years to be exonerated through DNA testing.
Reform Solution — “Fillers” (the non-suspects included in a lineup) should resemble the eyewitness’ description of the perpetrator. Further, the suspect should look similar to the fillers (for example, he should not be the only member of his race in the lineup, or the only one with facial hair). Eyewitnesses should also not view multiple lineups with the same suspect.
Problem — Often, the witness feels pressure to pick a perpetrator out of a lineup, even if they are unsure of whether one of the individuals, is in fact, the perpetrator.Reform Solution — The person viewing the lineup should be told that the perpetrator may or may not be in the lineup and that the investigation will continue regardless of the lineup result. This reduces the pressure on the witness of feeling like they have to pick a perpetrator. The witness should also be told not to look to the administrator for guidance.
- Confidence Statements
Problem — Studies show that eyewitnesses who were given confirmatory feedback on their identification inflated their recollections of the confidence they felt in their selections.Reform Solution — Law enforcement should elicit and document a statement from an eyewitness, in which the eyewitness provides a statement relating to his or her level of confidence in the identification at the time the identification is made. The confidence statement should be documented before any feedback is provided in order to capture a true sense of an eyewitness’s level of confidence at the time the identification is made and minimize the possibility that an inaccurate portrayal of confidence – based on memory alteration – is presented at trial.
Problem — It is sometimes difficult to present findings of error or misconduct made by the lineup administrator at trial; alternatively, it may also be difficult for a prosecutor to show the jury that a lineup procedure was legitimately conducted.Reform Solution — Identification procedures should be videotaped whenever possible.
Studies on blind administration of lineups: