The Pittsburgh Post-Gazette/Ipso Facto
April 27, 2012
Last fall, I wrote a series of blogs on the Report of the Advisory Committee on Wrongful Convictions issued by the Pennsylvania Joint State Government Commission. One portion of the report suggested that cognitive bias in a suspect line-up or photo array could be reduced by implementing some simple procedures.
There is an abundance of research that suggests eyewitness identification can be influenced by things that are said or done during the identification process. Most eyewitnesses are untrained civilians who may be for the first time encountering the criminal justice system.
However, we are learning that even highly trained professionals can be influenced by what they know about a case prior to their analysis of evidence.
Fingerprint analysis had been considered the gold standard of evidence. Until recently the FBI described fingerprint identification as 100 percent infallible, that is no longer the case. “There’s going to be, I think, variability anytime there’s a human involved in the process,” FBI expert Melissa Gische told PBS’s Frontline.
What do we know about fingerprints? Impressions of fingerprints are left behind on various surfaces by the natural secretions of sweat. The friction ridges, the raised portion of the epidermis on fingers consisting of one or more connected ridges, are often the point of comparison.
First, an intentional recording of the fingerprint is made with black ink on a white card or recorded digitally. These are often collected after arrest and kept in a database. At a crime scene a “latent print,” the chance recording of a fingerprint deposited on a surface, is captured through chemical methods and brought into a lab for expert analysis.
Fingerprint identification came under scrutiny in 2004. The FBI publicly acknowledged the fingerprint misidentification of an Oregon lawyer wrongfully implicated in a terrorist bombing in Madrid.
Since then, the Department of Justice has begun research to set standards for the analysis of fingerprints. As part of that process, the FBI has implemented “blind verification” of analysis by agents unfamiliar with initial examinations.
Through a study conducted in 2004, cognitive neuro-scientist Itiel Dror found that otherwise competent and well-meaning experts were swayed by what they knew about a case submitted for analysis. Dror’s study demonstrated that if an analyst new that the suspect confessed or was arrested, the analyst’s findings could be influenced. Cognitive bias seeped into the process even with the best trained experts.
The solution may be similar to those suggested for eyewitness identification. Bias can be muted by “blind” line-ups or arrays, where the police officer administering the line-up does not know the suspect. For forensic evidence, a blind analysis where the analyst knows nothing about the case, a step further than the FBI’s blind verification, may equally reduce bias.
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