False confessions can be disturbingly easy to generate in social experiments, particularly when persuasive techniques such as bluffing are used. A 2011 study from the City University of New York, the University of California-Irvine and Nova Southeastern University published in Psychological Science, “Confessions That Corrupt: Evidence from the DNA Exoneration Case Files,” examines the link between confessions and the corruption of other evidence in real-world situations.

The researchers examined 241 cases of exonerated individuals from The Innocence Project between 1992 and 2009 to determine the likelihood that a false confession taints other types of evidence, the kinds of evidence most affected by a false confession and how often this occurs.

Key findings include:

• False confessions were implicated in nearly 25% of the exonerations examined, but were less common than eyewitness false identifications (75%) or misuse of forensic evidence (51%).
• Nearly 78% of the cases associated with false confessions contained multiple types of problematic evidence, compared to only 47% of cases involving true confessions. Nearly 46% of false-confession cases contained one additional non-confession evidence error; 32% contained two or more.
• “False confessions were most often accompanied by invalid or improper forensic science, eyewitness identification mistakes and informants.”
• Researchers compared the prevalence of false confession errors to that of eyewitness errors, and determined that “pure confession cases contained more additional types of errors…. More specifically, pure confession cases were significantly more likely than pure eyewitness cases to be accompanied by forensic-science errors (67% vs. 45%).”
• If the false confession is among the first pieces of evidence collected, it tends to color the interpretation of subsequent evidence. Researchers found that “confessions were more likely to precede than to follow both forensic-science errors … and informant errors.”

Human error is often to blame for corrupted evidence, including scientific evidence: “As a result of scandalous improprieties in several crime laboratories and the frequency with which forensic-science errors had surfaced in wrongful convictions, the National Academy of Sciences (2009) was highly critical of a broad range of forensic disciplines.” The researchers note that their study focused on a limited number of variables, and suggest that a confession’s impact on case evidence may be more far-reaching than described in the study.

Tags: civil rights, crime, science

By Margaret Weigel | February 29, 2012