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.

In one recent study, the psychologists had 38 undergraduates enter a professor’s office and either steal an exam or replace one that had been stolen. A week later, half told the truth in this structured interview, and the other half tried not to incriminate themselves by lying in the interview. A prize of $20 was offered to the most believable liars.

The researchers had four trained raters who did not know which students were lying analyze the transcripts for response length and richness of added detail, among other things. They correctly categorized 33 of the 38 stories as truthful or deceitful.

The study, whose co-authors were Amina Memon, Laura Taylor and Jessica Prewett, is one of several showing positive results of about 75 percent correct or higher.

This summer, Dr. Colwell and Dr. Hiscock-Anisman are scheduled to teach the technique at the San Diego Police Department, which has a force of some 2,000 officers. “You really develop your own antenna when interviewing people over the years,” said Chris Ellis, a lieutenant on the force who invited the researchers to give training. “But we’re very open to anything that will make our jobs easier and make us more accurate.”