Effects of single and repeated shock on perceived pain and startle response in healthy volunteers

Contingent shock (CS) has been used in a number of studies to suppress health-threatening self-injurious behavior of individuals with mental retardation and autism. As sustained suppression is an issue of concern, research into procedural variables of CS is needed. In this study, clinical evidence was used to infer a variable that might be of relevance for the application of clinical contingent shock, that is, to assess the effect of single versus repeated shock at a specific location on the body. With pain intensity and startle response as dependent variables, shocks were administered to 48 healthy volunteers. Electric shocks were identical to those that used in clinical practice. The second shock in succession to the same location of the body produced higher pain intensity ratings than the first shock and that the third shock in succession to the same location of the body produced higher pain intensity ratings than the second shock in succession. Startle responses, however, failed to be affected in this direction. The latter result is consistent with a previous study. Our data suggest that repeated shock to the same location is likely to be more effective to establish suppression than repeated shock to different locations.