Monday, 28 January 2013
Bluffing in Interrogations Leads to False Confessions
When someone who was suspected of a crime confessed to it, that always used to be regarded as convincing evidence of his or her guilt. But with the advent of molecular biology, traces of DNA have been used to prove the innocence of many suspects, some 25% of whom had previously pleaded guilty or signed confessions after being interrogated.
How is this possible? The psychologists who study this question distinguish two main categories of factors that can lead suspects to incriminate themselves in this way. The first category consists of personal vulnerabilities, such as being young, or intellectually impaired, or having a compliant personality. The second consists of pressures inherent in the conditions of custody and interrogation, such as having an insufficient knowledge of the law, or being afraid of being assaulted, or threatened with a severe sentence, or subjected to torture that causes pain.
A study published in 2010 by Jennifer Perillo and Saul Kassin of the Department of Psychology at the John Jay College of Criminal Justice in New York examined one of the factors in this second category: bluffing. Bluffing during an interrogation means an interrogator’s claiming to have evidence, but not explicitly stating that this evidence involves the suspect being interrogated. In theory, for example, if an interrogator said that blood had been found at the crime scene and was being analyzed, this claim should exert pressure only on a suspect who was actually guilty, because anyone else would have nothing to fear. Or at least that is what was once believed.
But Perillo and Kassin’s experiments suggest otherwise. In these experiments, the participants—all student volunteers—were accused of the “crime” of having made a computer crash by pressing a key that they had been told not to press while performing another task. In fact, none of them had pressed this key, but the participants assigned to the “bluff ” group were told that the experimenter had evidence incriminating them, while the participants assigned to the control group were not. The students in the “bluff ” group falsely confessed to the “crime” more often than the students in the control group. The majority of the students who confessed said that they had done so because they expected to be proven innocent later on.
These results suggest an unconscious bias in the way that suspects reason. If this bias is confirmed in other studies, it might well raise questions about certain police practices that have probably resulted in many judicial errors.