Social modeling influences on sensory decision theory and psychophysiological indexes of pain.

Subjects exposed to social models dissimulating tolerance or intolerance generally exhibit matching behavior in their verbal ratings of painful stimulation. It has been unclear, however, whether these changes reflect voluntary alteration of evidence or genuine changes in distress. This study used alternative measures and controlled for methodological limitations of earlier studies by examining nonpalmar skin potential in addition to palmar skin conductance and heart rate indexes of psychophysiological response to electric shock, and by evaluating verbal expressions of pain with sensory decision theory methodology. Of 20 female volunteer subjects, half served as controls, and half were exposed to a tolerant female model. Both the subject and the model verbalized ratings of discomfort provoked by a series of electric shocks of increasing intensity. Subjects then underwent a series of preselected random shocks. Sensory decision theory analyses revealed lower discriminability of the shocks among subjects exposed to a tolerant model. Several indexes of nonpalmar skin potential and heart rate reactivity exhibited lower reactivity in the tolerant group. Tolerant modeling was also associated with decreases in subjective stress. The results were consistent with the position that changes in pain indexes associated with exposure to a tolerant model represented variations in fundamental characteristics of painful experiences as opposed to suppression of information.