Timing Behavior and Conditioned Fear

Abstract

Rats were trained on a two-response timing procedure which required that response B follow response A by at least a minimum specified interval in order to be reinforced with food. Repeated presentation (5 min on, 5 min off) of an auditory warning stimulus terminated by a brief electric shock to the feet (conditioned fear) produced a marked suppression in the frequency of A-to-B response sequences during the waming stimulus. The distribution of A-to-B interresponse times (timing behavior), however, did not change during the warning stimulus.The suppressing effect of conditioned fear (conditioned emotional response or CER) upon the rate of an ongoing lever-pressing response for food has been well documented in previous reports (Estes and Skinner, 1941;Brady and Hunt, 1955; Stein, Sidman and Brady, 1958). The present experiment examined the effects of the CER procedure upon properties of the operant behavior in addition to the response rate. Specifically, the effects of conditioned fear upon timing behavior using a two-response chain with a time delay required between responses was investigated. METHOD SubjectsThree experimentally naive male albino rats served. The principles of laboratory animal care as promulgated by the National Society for Medical Research were observed. ApparatusThe Ss were housed and tested in the elevator device shown in Fig. 1 the walls and grid floor of an individual test cage. Ad libitum water was provided from a bottle on the wall of each cage. When the test panel was in position in front of a cage, the S was presented with a response key on the left and right sides of the front panel, about nose high, a trough between the keys near the grid floor for pellet delivery, and a small speaker mounted in the center of the front panel near the ceiling. Under program control, the panel moved up from the home position at the bottom of the elevator, not facing any cage, to a cage in which an S lived for a test session. At the termination of the test for one S, the front panel moved up to a second S, and so on through the entire series before returning to the bottom of the elevator.Conventional relay circuitry was used to program the experimental contingencies. The data were recorded on punched paper tape for later sorting and computation by a digital computer. Parallel recording of some of the data by electro-mechanical impulse counters was used to verify the accuracy of the punched tape system. ProcedureOver the course of several days Ss were food deprived, magazine trained, and shaped to nose-press the illuminated key at the right (key B) for continuous reinforcement. Next, key A, on the left, was illuminated and key B was darkened. Pressing key B when darkened had no effect. Pressing key A when illuminated extinguished the light on key A and illuminated key B. A press on Key B at this time was reinforced, the key B light ex-247 VOLUME 7, NUMBER 3 MAY, 1964

EFFECTS OF PUNISHING ELEMENTS OF A SIMPLE INSTRUMENTAL‐CONSUMMATORY RESPONSE CHAIN1

“…For example, the primary effect of punishment of responding maintained by fixed-ratio schedules of positive reinforcement is to increase the pause characteristically exhibited after reinforcement, rather than to increase interresponse times within the ratio run (Azrin, 1959;Dar-(lano and Sauerbrunn, 1964). Similarly, Migler and Brady (1964) found that conditioned suppression of a sequence of two instrumental responses, the second of which was reinforced, was due to a reduction in the number of sequences initiated, rather than to an increase in the time intervening between the two responses. By contrast, Church (1969) found a selective effect of ptunishment on the punished component of an instrumental-consummatory response chain in a situation in which the component responses were spatially separated.…”

Response Rate Viewed as Engagement Bouts: Effects of Relative Reinforcement and Schedule Type

“…Then, if the pause has been sufficiently long, a press on a second lever (Lever B) is reinforced. It turns out that the Bto-A times are quite sensitive to various reinforcement and motivation-like operations (e.g., deprivation level) but that the A-to-B times are rather insensitive to such operations (Mechner & Guevrekian, 1962;Migler & Brady, 1964). In other words, the tendency to initiate (i.e., visit) the DRL segment is more sensitive to such operations than is the learned pattern of responding during the visit.…”

CONDITIONED SUPPRESSION OR FACILITATION AS A FUNCTION OF THE BEHAVIORAL BASELINE1

“…Perhaps it is the timing process generated by these schedules and not the recorded response which is disrupted. Migler and Brady (1964) considered this possibility. They performed an experiment in which two responses were used.…”