No abstract

The hypothesis was advanced that prompt CS termination on CR trials reinforces avoidance acquisition because it serves as an excellent discriminative cue for US avoidance rather than because it leads to fear reduction. It was shown that a cue other than prompt CS termination could serve this function both in delayed (Experiment I) and in trace (Experiment II) avoidance conditioning paradigms. The important role played by anticipatory responses-CRs which are independent of the avoidance contingency-in avoidance acquisition was pointed out.

In a two-choice discrimination situation, a cue-producing response produced the discriminanda for 0.05 sec. The cue-producing responses beyond those normally necessary to identify the discriminanda thus provided only redundant information. Two of the four Capuchin monkeys studied showed a large increase in cue-producing responses during reversal learning and extinction, and they reversed much faster than the two whose cue-producing responses showed little increase. During acquisition of a difficult discrimination, the cue-producing responses of the first two subjects reached a high level and during overtraining gradually reduced to their initial low level. The results were related to Wyckoff's theory of observing behavior and to the notions of uncertainty, reduction, and lack of information as extensions of the concepts of reinforcement and motivation.Observing behavior has been investigated in a number of different contexts. In one class of experiments, the observing response, though not associated with differential "primary" reinforcement, produces information (discriminative cues) which may provide the source of reinforcement for the observing behavior. For example, the fact that a pigeon continues to peck a key when the only consequence of this action is to produce a stimulus which provides information concerning the schedule in force on a second key (e.g., Hendry and Dillow, 1966;Kelleher, Riddle, and Cook, 1962), may be interpreted in terms of the conditionecl reinforcement arising from the response-produced stimuli. Experiments showing that rats learn to choose the side of an E-maze which provides information concerning the availability of reward, rather than the side on which the reinforcement schedule is precisely the same but without the information cue (e.g., Mitchell, Perkins, and Perkins, 1965;Prokasy, 1956), are also interpretable in terms of conditioned reinforcement. Both sets of results may be accommodated by the assumption that the conditioned reinforcement strength of a stimulus is a positively accelerated function of the (primary) reinforcement frequency with which the latter is correlate(d (cf. Kelleher et al., 1962;Wyckoff, 1959).The reinforcement for observing behavior in the vigilance situation, a second category of observing response experiments, is even more direct: detection of the target stimulus depends upon execution of the observing response (e.g., Holland, 1958). The observing behavior investigated in the present experiment is somewhat similar to that studied in the first class of experiments. The observing response, referred to here as a cue-producing response (CPR), gave the subject a brief glimpse of the discriminanda of a two-choice discrimination problem; this may be considered to comprise the conditione(l reinforcement for the cue-producing behavior. However, since on any given trial the information provided by each CPR was identical, additional responses beyond those normally required to identify the discriminanda provided only redundant information. The primary interest wa...

Effects of unpaired preacquisition exposure of CS and UCS on classical conditioning of the nictitating membrane response of the albino rabbit.

other anticholinergic drugs and the repeated failures to find such effects with anticholinergics which have primarily peripheral effects (e.g., Carlton, 1968; Whitehouse, Lloyd, & Fifer, 1964), it is perhaps safe to assume that the effects noted here are related to the attenuation of central-ACH activity. 3 REFERENCES CARLTON, P. L. Cholinergic mechanisms in the control of behavior by the brain. Psychol.