Effect of negative motivation on the behavioral and autonomic correlates of deception.

In forensic contexts, lying is often motivated by the will to avoid negative consequences (e.g., an arrest). Previous research investigating the effect of motivation on deception has, however, nearly exclusively focused on the effect of positive motivation (e.g., via financial rewards). In the current study, we aimed to replicate previous studies on the behavioral and autonomic correlates of deception and to investigate the influence of negative motivation on those correlates. Participants committed a mock theft and underwent a questioning procedure in which they had to truthfully and deceptively answer questions about the committed mock crime and a control crime. Half of the participants completed the procedure without any specific motivation, whereas the other half of the participants was told that lies detected by a computer algorithm would result in an unpleasant electric stimulation. Results revealed longer reaction times, larger skin conductance responses, and a relative heart rate slowing for lying compared to truth telling. The latter two effects were larger in the motivation compared to the control condition. Results are in line with the motivation impairment hypothesis and effects of positive motivation on the autonomic correlates of information concealment. The observation that a higher motivation increased rather than decreased deception effects is promising for forensic contexts. The possible explanation that these effects could be related to fear conditioning should stimulate future research on the stability of differences between lying and truth telling in people who experienced no or only seldom punishment for deception in their learning history.