“Weapons effect” revisited: Motor effects of the reception of aversive stimulation and exposure to pictures of firearms

The effect of presenting images of firearms on the speed of clenching of the fist of human subjects simultaneously receiving an aversive stimulation was studied. It was thought that, whereas the classic interpersonal experimental situation confounds the effects of the stimulus presented and several interpersonal processes, speed of fist clenching in a noninterpersonal setting could constitute a valid measure of the subject's readiness to fight. Twenty-four male and 24 female students (ages > 20 and <36 years) were instructed to press with their right hand a device commanding the projection of slides upon reception of an acoustic signal. Speed of clenching of the hand was recorded in the four conditions generated by the combination of two levels of acoustic signal (aversive and nonaversive) and two modalities of slides (firearms or tools). The results show that the reception of aversive sound accelerates fist clenching. Simultaneous presentation of slides of firearms and reception of aversive noise increases the speed of clenching of the fist. The slides' main effect was not significant. More irritable subjects tend to execute this movement faster than their less irritable counterparts, and more emotionally susceptible subjects tend to be slower than less susceptible ones. Male subjects were faster than females. This pattern of results is discussed in relation to the hypothesis formulated by the authors.