Choice reaction time and hand steadiness were studied under conditions in which correct performance of a task produced painful electric shock. Task performance deteriorated in response to shock. Deterioration was greater when shock was applied to the active hand than when applied to the passive hand. The hand steadiness test also involved variation in shock intensity and administration of aspirin or placebo. Tremor increased with shock intensity, and aspirin decreased the difference in performance between shock and nonshock trials. The methods employed offer a means of laboratory simulation of disability produced by pathological pain and a possible means of evaluation of analgesic effectiveness. Submitted on September 11, 1961