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How stress can lead to false confessions

Teresa Tanoos's picture
Study finds innocent people often pressured into making false confession

Anyone who has ever been wrongly accused of a crime will tell you it was stressful, but according to a study published in Law and Human Behavior, the innocent are frequently less stressed than the guilty – and that makes them more susceptible to admitting a crime they did not commit.

In an effort to find out what leads innocent people to making false confessions, researchers from Iowa State University launched a study that measured numerous indicators of stress, such as blood pressure, heart rate and nervous system activity.

The results showed that stress levels increased for all participants when they were first accused, but they were significantly lower for the wrongly accused. Researchers said that's a concern because it can make those who are innocent less likely to vigorously defend themselves in a real interrogation.

"The innocent are less stressed because they believe their innocence is going to protect them and they think everything is going to be OK, so there is no reason to get worked up over this accusation," said Stephanie Madon, an associate professor of psychology and researcher for the study.

"But if you're going into a police interrogation and you're not on your guard, then you could make decisions that down the line will put you at risk for a false confession. Because once you talk to police, you're opening up the chance that they're going to use manipulative and coercive tactics," Madon added.

Madon, along with Max Guyll, an assistant professor of psychology, said that minimization is one of those tactics used in interrogations and the tactic they used in their study.

As Guyll explained it, by minimizing the severity of a crime, investigators try to convince the person they are questioning that it's in their best interest to confess. Although it’s initially easy for the person to defend his or her self, they start to wear down over time.

"If you're brought in late at night and kept for several hours, you're exhausted, and you have these investigators who are in a position of power. They're challenging everything you say and they're not accepting anything you say," Guyll said. "That pressure starts to take a toll physiologically and there's a greater chance you'll give up and confess."

As one can imagine, once an innocent person ends up making a confession to a crime they did not commit, the stress they previously minimized starts taking a toll.

Accordingly, the Innocence Project, a nonprofit group that works to exonerate those who are wrongly convicted, set out to help clear the innocent, many of whom were wrongly convicted due to false confessions. To date, the organization has helped clear 80 people who admitted to crimes they did not commit.

Madon said that other researchers have also studied false confession cases in which police recorded the length of the interrogation. Among those cases, they found that people were questioned for up to 16 hours on average before admitting to a crime they did not commit.

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"These people held out for a very long time, but they couldn't hold out forever," Madon said. Interrogations usually last only 30 minutes to 2.5 hours, but with some false confessions, individual suspects were questioned for up to 24 hours.

"Being in a police interrogation is a very powerful situation," Guyll said. "If you wear a person down you can probably get false confessions."

Students from Iowa State University were recruited to serve as participants for the study, and it took only a brief amount of time for some to confess. The students were connected to monitors that allowed researchers to measure their stress levels at different points during the experiment.

This is the first study to look at physiological response, which is important because the results cannot be easily misrepresented or unfairly influenced if the researchers asked students how much stress they felt when accused.

For the experiment, the students were given an assignment, a portion of which was to be completed individually, and the rest 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.

The students, both the innocent and the guilty, were later accused of academic misconduct and asked to sign a form confessing. The researchers found that 93 percent of the guilty students confessed, but 43 percent of those who were innocent also agreed to sign the confession form.

While the innocent showed less stress than the guilty when first accused of misconduct, that changed when students were further pressured to sign a confession. Compared with students who gave up and confessed, the innocent who refused to confess showed increased 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 energy could start to take a toll, Guyll said, adding that this could 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," he explained.

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

SOURCE: Law and Human Behavior, "Innocence and Resisting Confession During Interrogation: Effects on Physiologic Activity," Max Guyll, Stephanie Madon, Yueran Yang, Daniel G. Lannin, Kyle Scherr, Sarah Greathouse. August 5, 2013; DOI: 10.1037/lhb0000044