Wrongful convictions can be reduced through science, but tradeoffs exist

May 22, 2012

Many of the wrongful convictions identified in a report this week hinged on a misidentified culprit — and a new report in a top journal on psychological science reveals the paradox of reforms in eyewitness identification procedure. In our efforts to make sure that good guys don't get locked up, we could let more bad guys go.

In the May issue of Perspectives on Psychological Science, a journal of the Association for , leading scholars in psychology and the law explore and debate various aspects of eyewitness identification procedures, providing a scientific foundation for this important social issue.

In recent years, researchers and policymakers have called for specific reforms to eyewitness identification procedures that would help to reduce the rate of false identification. These reforms affect various aspects of identification procedure, including how lineups are constructed, what witnesses are told prior to the lineup, and how police officers should behave during the procedure.

Such procedural reforms are often viewed as having 'no cost' – they reduce the false identification rate without affecting the correct identification rate. But psychological scientist Steven Clark (University of California, Riverside) argues that 'no cost' view may not actually be true. After extensive review of the existing data, Clark points out the paradoxical tradeoffs to reforms in eyewitness identification procedure. Existing data suggest that when we choose to enact reforms that are designed to reduce false identifications, we may also reduce the number of correct identifications at the same time.

But this tradeoff does not tell the whole story, say Gary Wells (Iowa State University), Nancy Steblay (Augsburg College), and Jennifer Dysart (John Jay College of Criminal Justice). While reform procedures may reduce the number of 'hits,' they do so by minimizing the influence of suggestive and coercive practices, such as biased instructions and cues from lineup administrators. Wells and his co-authors argue that the so-called 'lost' hits aren't actually relevant, because hits that result from suggestive practices are not legitimate identifications. Eryn Newman from Victoria University of Wellington and Elizabeth Loftus from the University of California, Irvine agree, arguing that eyewitness identification evidence should be based solely on the independent memory of the witness, not on the results of suggestive or coercive procedures.

There is, however, a scientifically valid way to compare witness-identification procedures, say John Wixted and Laura Mickes, both of the University of California, San Diego. If we identify the procedures that reliably differentiate between innocent and guilty suspects over time and across different situations, we will be able to determine which techniques are diagnostically superior to others.

Until we have such comprehensive data, the best way to protect innocent defendants, says Larry Laudan of the University of Texas, is by clearly communicating the fact that eyewitness identifications, regardless of their format, are fallible. According to Laudan, we now have enough empirical data to be able to inform jurors about the error profiles of various procedures. Sharing this information, he argues, is more important than trying to arrive at "the one unique and definitive format for conducting identifications."

In the end, Clark points out that the goal of his article is not to argue for or against any particular witness identification procedure. Rather, he hopes to create strong links between social science data and public policy. "To the extent that social science research has a useful role in shaping policy decisions," says Clark, "social scientists must do for policymakers what they do best and what policymakers cannot do for themselves: conduct careful studies, and provide a clear and complete analysis of the empirical data."

Explore further: Understanding the science of eyewitness identifications

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