Autonomic and behavioral responding to concealed information: differentiating orienting and defensive responses

A mock crime experiment was conducted to examine whether enhanced responding to concealed information during a polygraph examination is due to orienting or defensive responding. Thirty-six undergraduate students enacted one of two mock crimes. Pictures related to both crimes were presented while heart rate, magnitude of the skin conductance response, and reaction times to a secondary probe were measured. Compared to control pictures, participants showed heart rate deceleration and enhanced electrodermal responding to pictures of the crime they had committed. Probe reaction times did not differ significantly between crime and control pictures. The present findings support the idea that the orienting reflex accounts for the enhanced responding to concealed information. Theoretical and practical implications of the orienting account are discussed.