Persistent Behavior Maintained by Unavoidable Shocks

Abstract

Squirrel monkeys were trained on a multiple schedule in which 10-min periods on a continuous shock avoidance schedule, indicated by a yellow light, alternated with 10-min periods on a 1.5-min variable interval schedule of food reinforcement (VI 1.5). A white light indicated that VI 1.5 was in effect, except for the middle 2 min of the period on VI 1.5, in which a blue light appeared and terminated with the delivery of a 0.5-sec unavoidable shock. Stable response rates developed in the avoidance and VI 1.5 components. However, the highest response rates occurred in the blue, preshock stimulus. A series of experiments showed that responding in the blue stimulus persisted even when responding had been extinguished on both the VI schedule of food reinforcement and the shock avoidance schedule. Responding in the blue stimulus ceased when the blue stimulus terminated without shock or when it terminated with a response-contingent shock. Each time responding ceased, it was restored by terminating the blue stimulus with an unavoidable shock. When the blue stimulus was on throughout each session and unavoidable shocks were delivered at regular 10-min intervals, responding was well maintained. These results show that in monkeys that have been trained on a continuous avoidance schedule, unavoidable shocks can maintain responding even under conditions where responses have no programmed consequences. Estes and Skinner (1941) demonstrated that a stimulus (pre-aversive stimulus) that repeatedly preceded an unavoidable shock suppressed the responding of rats on a fixed-interval schedule of food reinforcement. Many subsequent studies have extended this finding by showing that a pre-aversive stimulus suppresses the response rates of several other species on various schedules of positive reinforcement (e.g., Brady, 1955;Brady and Hunt, 1955;Azrin, 1956;Sidman, 1956;and Valenstein, 1959 the relative durations of the presence and absence of the pre-aversive stimulus; the degree of suppression was inversely related to the percentage of time that the pre-aversive stimulus was present.Sidman, Herrnstein, and Conrad (1957) first demonstrated that a pre-aversive stimulus could increase responding when a continuous shock avoidance schedule (Sidman, 1953) was used to maintain behavior; with further exposure to this procedure, however, the response rate during the pre-aversive stimulus gradually decreased toward the response rate that prevailed between presentations of the pre-aversive stimulus. When the conditioned avoidance response was extinguished, response rates decreased more slowly in the presence of the pre-aversive stimulus than in its absence.Herrnstein and Sidman (1958) found that -if monkeys had been previously conditioned on a shock avoidance schedule, the EstesSkinner procedure produced increased response rates in the pre-aversive stimulus even when a VI schedule of food reinforcement was used to maintain behavior. If the conditioned avoidance response was extinguished before the Estes-Skinner procedure -was instituted, respon...

PATTERNING WITH FIXED‐TIME SCHEDULES OF RESPONSE‐INDEPENDENT REINFORCEMENT1

“…When Sidman, Herrnstein, and Conrad (1957) maintained responding with a continuous shock-avoidance schedule, the superimposition of a stimulus correlated with electric shock presentation according to a fixedtime schedule resulted in positively accelerated responding. Kelleher, Riddle, and Cook (1963) demonstrated that the fixed-time shock schedule would maintain this pattern even when the response-dependent schedule was discontinued. These experiments involving responding maintained by shock are important demonstrations that the effects of a schedule depend on a complex of conditions.…”

A test of the Wagner-Rescorla model’s prediction of no response decrement in a nondifferential following a differential schedule of reinforcement

“…When US presentations in extinction retard the rate of response cessation relative to that rate obtained with CS-alone extinction, as has been demonstrated most powerfully for avoidance and escape responses (Coulson, Coulson, & Gardner, 1970;Fowler, 1971;Kelleher, Riddle, & Cook, 1963;McKearney, 1969;Stretch, Orloff, & Dalrymple, 1968) but also for conditioned suppression (Ayres & DeCosta, 1971) and leverpressing (Rescorla & Skucy, 1969) in rats, an explanation in terms of the adventitious temporal contiguity of response and reinforcement (Skinner, 1948) is probably most common. Other investigators have emphasized the discriminative properties of reinforcement (Rescorla & Skucy, 1969;Uhl, 1973;Zeiler, 1968).…”

Brief Exposure to Contingent Reinforcement Produces a Sustained Increment in the Strength of an Elicited Response

“…Several previous studies have reported sustained responding following termination of a shock-avoidance contingency during periods of continued shock or shock-correlated stimulus delivery (Herrnstein & Sidman, 1958;Kelleher, Riddle, & Cook, 1963;Sidman, Herrnstein, & Conrad, 1957;Waller & Waller, 1963). In those studies, original examination of behavior began with the operant conditioning of lever pressing or panel pressing with reinforcement via food delivery and/ or shock avoidance.…”