WASHINGTON, Nov. 17 (UPI) -- A false confession to a crime can lead to subsequent errors in testimony and evidence both from laypeople and forensic experts, U.S. psychologists say.
False confessions frequently play a major role in convicting innocent people, and studies have shown juries and potential witnesses are influenced by confessions even if they know they were coerced.
In addition, experienced polygraph examiners, fingerprint experts and other experts, when told of a confession, see what they expect to see --that is, evidence of guilt, said John Jay College of Criminal Justice psychologist Saul Kassin.
Kassin and colleagues reviewed the trial records of 241 people exonerated by the Innocence Project since 1992, and found that multiple errors turned up far more often in false confession cases than in eyewitness cases.
And two thirds of the time, the confession came first, followed by other errors, namely invalid forensic science and government informants, the study, published in Psychological Science, reported.
The study throws doubt on a critical legal concept designed to safeguard the innocent: corroboration. Appeals courts will uphold a conviction even if a false confession is discovered, as long as other evidence -- say, forensics or other witness testimony -- independently shows guilt.
"What these findings suggest is that there may well be the appearance of corroboration," Kassin said, "but it is false evidence that was corrupted by the confession -- not independent at all."
