Judging Honesty by Words, Not Fidgets

From the New York Times May 12, 2009

Before any interrogation, before the two-way mirrors or bargaining or good-cop, bad-cop routines, police officers investigating a crime have to make a very tricky determination: Is the person I'm interviewing being honest, or spinning fairy tales?

Until recently, police departments have had little solid research to guide their instincts. Now forensic scientists have begun testing techniques they hope will give officers, interrogators and others a kind of honesty screen, an improved method of sorting doctored stories from truthful ones.

The new work focuses on what people say, not how they act. It has already changed police work in other countries, and some new techniques are making their way into interrogations in the United States. In part, the work grows out of a frustration with other methods.

Liars do not avert their eyes in an interview on average any more than people telling the truth do, researchers report; they do not fidget, sweat or slump in a chair any more often.They may produce distinct, fleeting changes in expression, experts say, but it is not clear yet how useful it is to analyze those.

Nor have technological advances proved very helpful. No brain-imaging machine can reliably distinguish a doctored story from the truthful one, for instance.

"Focusing on content is a very good idea," given the limitations of what is currently being done, said Saul Kassin, a professor of psychology at John Jay College of Criminal Justice.

One broad, straightforward principle has changed police work in Britain: seek information, not a confession. In the mid-1980s, following cases of false confessions, British courts prohibited officers from using some aggressive techniques, like lying about evidence to provoke suspects, and required that interrogations be taped.

Officers now work to gather as much evidence as possible before interviewing a suspect, and they make no real distinction between this so-called investigative interview and an interrogation, said Ray Bull, a professor of forensic psychology at the University of Leicester.

"These interviews sound much more like a chat in a bar," said Dr. Bull, who, with colleagues like Aldert Vrij at the University of Portsmouth, has pioneered much of the research in this area. "It's a lot like the old 'Columbo' show, you know, where he pretends to be an idiot but he's gathered a lot of evidence."Dr. Bull, who has analyzed scores of interrogation tapes, said thepolice had reported no drop-off in the number of confessions, nor major miscarriages of justice arising from false confessions.

In one 2002 survey, researchers in Sweden found that less- confrontational interrogations were associated with a higher likelihood of confession.

Still, forensic researchers have not abandoned the search for verbal clues in interrogations.In analyses of what people say when they are lying and when they are telling the truth, they have found tantalizing differences.

Kevin Colwell, a psychologist at Southern Connecticut State University, says that people concocting a story prepare a script that is tight and lacking in detail. "It's like when your mom busted you as a kid, and you made really obvious mistakes, Well, now you're working to avoid those."

By contrast, people telling the truth have no script, and tend to recall more extraneous details and may even make mistakes.They are sloppier.

Psychologists have long studied methods for amplifying this contrast. Drawing on work by Dr. Vrij and Dr. Marcia K. Johnson of Yale, among others, Dr. Colwell and Dr. Cheryl Hiscock-Anisman of National University in La Jolla, Calif., have developed an interview technique that appears to help distinguish a tall tale from a true one.

The interview is low-key but demanding. First, the person recalls a vivid memory, like the first day at college, so researchers have a baseline reading for how the person communicates.

The person then freely recounts the event being investigated, recalling all that happened. After several pointed questions ("Would a police officer say a crime was committed?" for example), the interviewee describes the event in question again, adding sounds, smells and other details.

Several more stages follow, including one in which the person is asked to recall what happened in reverse.

In several studies, Dr. Colwell and Dr. Hiscock-Anisman have reported one consistent difference: People telling the truth tend to add 20 to 30 percent more external detail than do those who are lying. "This is how memory works, by association," Dr. Hiscock-Anisman said.

"If you're telling the truth, this mental reinstatement of contexts triggers more and more external details."

Not so if you've got a concocted story and you're sticking to it.

"It's the difference between a tree in full flower in the summer and a barren stick in winter," said Dr. Charles Morgan, a psychiatrist at the National Center for Post-Traumatic Stress Disorder, who has tested it for trauma claims and among special-operations soldiers.

The science is evolving fast. Dr. Bull, Dr. Vrij and Par-Anders Granhag at Goteborg University in Sweden are finding that challenging people with pieces of previously gathered evidence, gradually introduced throughout an investigative interview, increases the strain on liars. And it all can be done without threats or abuse, which is easier on officers and suspects.

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