EVIDENCE FOR A MOTOR MECHANISM OF PAIN-INDUCED AGGRESSION INSTIGATIONIN HUMANS

The automatic skeletal motor responses of 20 male and 20 female studen t subjects (aged 20-36) receiving a painful stimulation (electric shoc k) were studied by examining voluntary concomitant extensions and flex ions of the arm. These movements were either of long duration, allowin g for an on-line control of their execution or, of short duration, req uiring extensive pre-programming. Subjects were instructed either to p ush or to pull a lever upon receipt of an acoustic signal, which was p aired or unpaired with an electric shock. Latencies for long duration movements (regardless of direction) were reduced by reception of painf ul stimulation. Latencies of short duration extensions and flexions we re respectively reduced and increased by painful stimulation. Latencie s of short duration movements were larger for females than males, rega rdless of movement direction. These data suggest that painful stimulat ion elicits automatic movements which affect programming of the termin ation of simultaneous voluntary movements. Implications of these findi ngs for the study of aggressive behavior are discussed. (C) 1994 Wiley -Liss, Inc.