Eyewitness Misidentification of Suspects
Using research to make better photo lineupsBy Scot DuFour | Jul 19, 2017
According to the Innocence Project, there have been 350 people in the United States exonerated by DNA testing for crimes they did not commit. The causes of wrongful conviction are likely numerous but one statistic from the Innocence Project stands out: 71% of those 350 cases involved the incorrect identification of the suspect by a witness. Clearly we need to search for reasons that witnesses misidentify so many suspects and strive to correct the problem so we are arresting the right people.
Research on Lineups
Research suggests that lineups are not exceptionally reliable, but there are some consistent ways to conduct lineups that increase their efficacy.
Research shows that in traditional simultaneous lineups, for example, where a witness is shown an array of six photographs, the witness will choose someone 60% of the time even if the lineup does not contain the suspect.i Some researchers believe that the simultaneous lineup allows the witness to compare all the photos together, which results in the witness choosing the person that looks most like the suspect.
Sequential lineups attempt to overcome the obvious limitation of simultaneous lineups by showing the witness one photo at a time. Sequential lineups have been found to decrease the chance of false identification by 25% compared to simultaneous lineups.ii The same study found that increasing the number of photos shown to a witness in the simultaneous lineup also increases witness selection accuracy.
A study that created sequential lineups of up to twenty photographs found that witnesses were less likely to choose an innocent from the pictures.iii Even during the twenty photo sequential lineup 7% of the witnesses chose an innocent before choosing the actual culprit later in the lineup. This finding means that creating a sequential twenty photo lineup that only allows a witness to choose one photograph runs the risk of identifying innocents as the suspect. The benefits of allowing a witness to choose multiple photographs during the sequential lineups include more correct suspect selections and by choosing more than one photograph from the lineup the evidentiary weight of the lineup is not so great as to be the sole factor for conviction.
The research on lineups clearly favors the sequential lineup over simultaneous lineups by reducing misidentifications from 25% on simultaneous lineups that do not include the suspect to 7% during sequential lineups in which the witness did eventually choose the correct suspect. One potential downfall of the sequential lineup is an apparent decrease in the witness choosing the guilty personiv, but this weakness is acceptable where the importance of limiting misidentification of innocents is greater than certainty of identifying the suspect.
It’s common knowledge that memory can fade with time and the ability to recognize someone or remember who they are is something that can diminish. One study using lineups found that only 7.8% of witnesses could identify the correct suspect after 24 hours had passed compared to 34.2% after just two hours.v
Determining the best person to administer the lineup to the witness is important. Several studies have found that when the administrator of the lineup knows the location of the suspect among the photos the administrator unknowingly influences the witness.vi A double-blind lineup occurs when one detective creates the lineup and knows the location of the suspect but a second detective that does not know the suspect administers the lineup to the witness.
To do our best at protecting the innocent and locking up the bad guy we need to recognize the weaknesses of our methods. Research on lineups shows that sequential lineups of more than six photographs administered in a timely and double-blind manner is a good way of preventing witness misidentification.
i A.M. Levi, “Protecting innocent defendants, nailing the guilty: A modified sequential lineup,” Applied Cognitive Psychology 12 (1998).
ii Steblay, Dysart, Fulero, and Lindsay. “Eyewitness accuracy rates in police showup and linup presentations: A meta-analytic comparison.” Law and Human Behavior 27 (2003).
iii A.M. Levi (1998).
iv Wilson, Hugenberg, and Bernstein. “The cross-race effect and eyewitness identification: How to improve recognition and reduce decision errors in eyewitness situations.” Social Issues and Policy Review 7 (2013).
v A.M. Levi (1998).
vi Wilson, Hugenberg, and Bernstein (2013).