PORTSMOUTH, England, June 8 (UPI) -- Police manuals often recommend methods to help investigators use visual and speech-related cues, but British research shows the cues are unreliable.
But researchers at the University of Portsmouth say that placing additional mental stress on interviewees could help police identify deception.
A series of experiments involving over 250 student "interviewees" and 290 police officers had interviewees either lie or tell the truth about staged events. Police officers were then asked to tell the liars from the truth tellers using the recommended strategies.
Those paying attention to visual cues proved significantly worse at distinguishing liars from those telling the truth than those looking for speech-related cues.
However, liars appeared less nervous and more helpful than those telling the truth -- contrary to the advice of the Behavioral Analysis Interview strategy, which uses verbal and non-verbal responses.
But when the researchers added to the "cognitive load" by asking the participants to tell their stories in reverse order significantly more non-verbal cues occurred and police officers were better able to discriminate between truthful and false accounts, according to the findings published at Economic and Social Research Council Society Today.