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Researchers say liars under scrutiny can't completely suppress facial expressions

Published July 13, 2011

Mark Frank has spent two decades studying the faces of people lying when in high-stakes situations and has good news for security experts.

“Until this study, research had not shown whether or not liars could suppress elements of their facial expression as a countermeasure.”
Mark Frank, Professor
Department of Communication

"Executing Facial Control During Deception Situations," a study he co-authored with former graduate student Carolyn M. Hurley, PhD, reports that although liars can reduce facial actions when under scrutiny, they can't suppress them all.

Frank, PhD, a professor of communication at UB, supervised and co-wrote the study with lead author Hurley, now a research scientist at the U.S. Transportation Security Administration.

Published earlier this year in the Journal of Nonverbal Behavior, the study examined whether subjects could suppress facial actions like eyebrow movements or smiles on command while under scrutiny by a lie catcher.

It turns out subjects could to a degree, but not completely and not always.

The results are derived from frame-by-frame coding of facial movements filmed during an interrogation in which participants, some lying, some telling the truth, were asked to suppress specific parts of facial expressions. Hurley and Frank found that these actions can be reduced, but not eliminated, and that instructions to the subjects to suppress one element of expression resulted in reduction of all facial movement, regardless of their implications for veracity.

Despite these findings, the majority of the 60 study participants reported believing that they had controlled all facial movement and had remained "poker faced" during the interview/interrogation.

"Behavioral countermeasures," says Frank, "are the strategies engaged by liars to deliberately control face or body behavior to fool lie catchers. Until this study, research had not shown whether or not liars could suppress elements of their facial expression as a countermeasure.

"As a security strategy," he says, "there is great significance in observing and interpreting nonverbal behavior during an investigative interview, especially when the interviewee is trying to suppress certain expressions."

Click here for a news interview in which Frank describes elements of his research.