Journal oi Abnormal Psychology 1966, Vol. 71, No. 2, 87-94 THE REDUCTION OF UNCERTAINTY CONCERNING FUTURE PAIN 1 AUSTIN JONES University of Pittsburgh P. M. BENTLER University of California at Los Angeles GEORGIA PETRY Psychological Service of Pittsburgh Ss received series of electric shocks to the forearm in which the temporal schedule and the sequence of shock intensities were associated with varying levels of randomness or uncertainty. The Ss were permitted an instrumental response which produced, in advance, information concerning 1 or both of these aspects of the shocks. Such information functioned as a strong positive reinforcement for most Ss. Instrumental response rate was a significant in- creasing function of the degree of uncertainty associated with the shock series, and occurred significantly more often for information concerning the temporal occurrence of shock than for its intensity. Studies of information deprivation have shown that the reduction of uncertainty re- garding series of photic stimuli reinforces instrumental response and that the rate of response is an increasing linear function of the magnitude of the uncertainty reduced (Jones, 1961, 1964, 1966; Jones, Wilkinson, & Braden, 1961). In these experiments the reduction of uncertainty through the presenta- tion of series of brief light flashes varying in their statistical properties appears to consti- tute a reinforcement principle that is inde- pendent of any observable, direct association with a previously established primary or sec- ondary reinforcement. This suggests that the reduction of uncertainty may be a dimension of reinforcement of considerable generality— serving to modify a wide range of human behaviors. The purpose of the present study was to assess the human motivational processes associated with the reduction of uncertainty concerning future pain. The subjects experi- enced various conditions with the instruction that some brief, painful electric shocks to study was supported in part by Grant MH 07632 from the National Institute of Mental Health, United State Public Health Service. Experiment II is based upon a master's thesis submitted by the third author to the Graduate Faculty of the Uni- versity of Pittsburgh. the forearm would occur, but that the sched- ule of shocks and their intensity would be probabilistically determined, so that the sub- ject would always be in some measure un- certain as to the characteristics of the stimu- lation he would receive. The subject was permitted an instrumental response which would provide information (uncertainty- reduction) concerning future shocks in the form of messages transmitted via earphones. In the first of two experiments, it was hy- pothesized (a) that the majority of subjects would perform such responses, (b) that re- sponse rate would be an increasing function of the degree of uncertainty associated with the temporal sequence of the shocks, and (c) that response rate would be greater when associated with the reduction of uncertainty concerning two stimulus dimensions rather than one. The expectation that the majority of subjects would perform the uncertainty- reducing responses was based upon the view that the reduction of uncertainty permits the subjects to make responses which serve to minimize pain and/or anxiety. Such responses may be of a "central" or ideational type, such as thinking to oneself "I don't have to be anxious about the shock now because it is not due for 1-J minutes," or of a motor type, such as waiting relaxed till the shock 87