Five individuals, who were treated for severe self-injurious behaviors (SIB) with contingent electric shock, participated. Hereby, each occurrence of the target response was followed by a remotely administered aversive consequence. Participants' heart rates were compared at times when the active device of the equipment for the above procedure was attached to their body and when the active device was detached. Although typical response patterns emerged across the participants results demonstrated that heart rates were lower when the active device was attached, tentatively supporting the notion that anxiety and stress may be collateral to participants' SIB.