Being wrongfully accused, it’s a nightmare I hope never to experience. This new research by Max Guyll, an assistant professor of psychology, and Stephanie Madon, an associate professor of psychology, shows that stress may lead to false confessions. To better understand what leads to false confessions, they  measured various indicators of stress, such as blood pressure, heart rate and nervous system activity. In the study the stress levels increased for all participants when they were first accused. However, the levels for those wrongly accused were significantly lower. Researchers said that’s a concern because it can make the innocent less likely to vigorously defend themselves in a real interrogation.

From the press release, how the study worked:

For students participating in the ISU study, it took only a short amount of time for some to confess. Students were connected to monitors so that researchers could measure their stress levels at different points throughout the experiment. The study is the first to look at physiological response, which is important because the results cannot be easily altered or influenced by bias if the researchers had asked students how much stress they felt when accused.

Madon said the students were given an assignment, part of which was to be completed individually and the other part with a partner. The experiment was set up so that the partner would ask some students for help with the individual task, essentially getting them to break the rules, so they would be guilty of misconduct.

Students, both innocent and guilty, were later accused of academic misconduct and asked to sign a form confessing. It came as no surprise to researchers that 93 percent of the guilty students confessed, but 43 percent of those who were innocent also agreed to sign the confession form.

Although the innocent showed less stress than the guilty when first accused of misconduct that changed when students were pressured further to sign a confession. In comparison to students who gave up and confessed, the innocent who refused to confess showed greater sympathetic nervous system activity, which is associated with the fight or flight response.

If questioned for a long period of time, the greater expenditure of resources could start to take a toll, Guyll said. And as a result, cause even more of the innocent to lose their energy and motivation to continue defending themselves, ultimately leading them to give up and confess.

“Everyone’s resources are drained over time, and this is made even worse when investigators constantly pressure the suspect and dispute their story,” Guyll said. “If you’ve ever been in an hour-long argument with someone, just think how exhausting that is, and how you get to a point where you will say you are wrong just to make it stop. Now imagine that argument going on for 16 hours.”

Researchers also videotaped the experiment to look at differences in body language and facial expressions among the different groups. While some students had a nervous smile or laughter, there was no measurable difference in the responses between the guilty and wrongly accused.

Abstract of the research:

Innocent suspects may not adequately protect themselves during interrogation because they fail to fully appreciate the danger of the situation. This experiment tested whether innocent suspects experience less stress during interrogation than guilty suspects, and whether refusing to confess expends physiologic resources. After experimentally manipulating innocence and guilt, 132 participants were accused and interrogated for misconduct, and then pressured to confess. Systolic and diastolic blood pressure (SBP, DBP), heart rate (HR), respiratory sinus arrhythmia (RSA), and preejection period (PEP) responses quantified stress reactions. As hypothesized, the innocent evidenced smaller stress responses to interrogation for SBP, DBP, HR, and RSA than did the guilty. Furthermore, innocents who refused to confess exhibited greater sympathetic nervous system activation, as evidenced by shorter PEPs, than did innocent or guilty confessors. These findings suggest that innocent suspects underestimate the threat of interrogation and that resisting pressures to confess can diminish suspects’ physiologic resources and lead to false confessions.