Vocal and verbal indicators of deception as a function of lie complexity

The aim of the present experiment was to explain contradictory findings in the relation ship between speech disturbances and deception. We hypothesized that lie complexity would have an impact on the occurrence of speech disturbances during deception. We expected liars to use fewer speech disturbances (compared to truth tellers) when the lie is easy but to make more speech disturbances when the lie requires a lot of mental effort. We further hypothesized that truth tellers would include more details in their recall and would raise more doubts about their own memory than liars. Forty participants were shown a video and were requested to lie about some aspects of the video and tell the truth about other aspects of the video. One lie (giving an inaccurate description of the appearance of one of the people in the video) was easy to fabricate, another lie (making up a reason why the person in the video wanted to buy satellite television) was difficult to fabricate. The results generally supported the hypotheses.