The laboratory measurement of human anger

A method was developed for the unobtrusive measurement of the frequency, duration, and intensity of nonfunctional jaw contractions in humans. Employing this method, several experiments explored the environmental causes of jaw clenching. Jaw contractions were differentially increased by the delivery of noise, the cessation of cigarette smoking, or the termination or reduction of both response-dependent and response-independent money and points convertible into money. In another experiment progressive increases and decreases in amounts of response-independent money decreased and increased jaw clenching. The recent history of reinforcement magnitude was more influential than the absolute level of contemporary reinforcement. The temporal distribution of jaw clenching relative to either reinforcement-maintained or reinforcement-independent concurrent responding closely paralleled relationships which have been previously reported between overt attack behavior in animal species and comparable experimental operations. Occasional instances of overt aggressive behavior corresponded to increased frequencies of jaw clenching. In humans, jaw contractions appear to be a sensitive and valid measure of the propensity to attack.