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Showing posts from May, 2018

We find the defendant....

If you’ve ever heard the jury foreman give a jury’s decision, you’ll notice that they never say the defendant is “innocent.” Instead, they’ll conclude that the defendant is “not guilty.” Although the terms may sound interchangeable, “not guilty” and “innocent” actually mean two different things. “Not guilty” is a legal conclusion, whereas “innocent” means the person didn’t commit the crime. For example, think of O.J. Simpson. In a court of law, he was found “not guilty” of killing his ex-wife – but if you ask the majority of Americans, they’ll tell you he’s not innocent. Here, we’re going to talk a bit about the distinction between the two conclusions – and why it matters to psychology and law researchers*.

When we say that “not guilty” is a legal decision, we mean that it’s a decision based on criteria described by laws – namely in the U.S., if the prosecutor can convince the jury of the defendant’s guilt. This is based partially on the amount of evidence that points toward the defend…

The experiment requires you to continue

Authority plays a prominent – perhaps obvious – role in the legal system. Police, lawyers, and judges all wield prestige and authority. Psychologists have been interested in people’s tendency to obey authority for decades, and much of our understanding of the psychology of authority is built on the work of one man. If you’ve taken an introductory psychology class, you have probably heard about Stanley Milgram’s studies on obedience to authority. Milgram’s program of obedience research is some of the most famous – if not the most famous – work in psychology. Many people have heard of Milgram’s work, but most people don’t know the details of his experiments or about the follow-up work of researchers who came after him.

In the most well-known version of Milgram’s obedience experiment procedure1, an experimenter first greets two participants and explains that they are to take part in a study on the role of punishment in learning. The experimenter (apparently) randomly assigns one of the …

Line 'em up and pick 'em out

The eyewitness lineup is an iconic scene in criminal investigations. Just reading that sentence probably summoned up a specific image in your mind: the one way glass, separating two very different rooms. In the first, four to eight (probably) men stand, slightly nervous, staring straight ahead. In the other, an officer stands with an eyewitness, asking them if they recognize any of the people in the other room. Sometimes, the witness is seated at a desk looking at photographs of the men. In either situation, your eyes are drawn to one guy in particular. The witness thinks for a long time, and then picks a person. The officer gives a huge sigh of relief and reassures the witness, “You picked the guy, thanks.”

This stereotype of eyewitness lineups is likely based on movies and media – and it is, in many instances, consistent with how lineups are conducted in real life. Unfortunately, many of the things that happen in lineups like this are problematic can lead to the wrong person being…

Danger: Risk of contaminated false confessions

Guest post by Fabiana Alceste.
In 1994, a Washington, D.C. detective named James Trainum questioned a woman under suspicion of homicide. After a 16-hour interrogation, the woman relented and provided a detailed narrative of how she and two other men killed a man and threw him in the Anacostia River1. Her confession seemed perfect—she incriminated herself and included accurate and privileged information about the crime that only the police and the true perpetrator could have known.

After the confession, Trainum and his colleagues naturally considered the case closed. Although investigators could not find any other evidence against the suspect, her confession reinforced the investigators’ belief in her guilt – in part, because it contained those accurate details. Soon after, the investigation showed that it was impossible for this woman to have committed the crime—she had an ironclad alibi—and the charges against her were dropped. But how could she have possibly known the details of the …