Sequential response effects in the white rat during conditioning and extinction on a DRL schedule,

Sequential IRT data were obtained for three rats on a DRL 60-sec reinforcement schedule. It was found that first-order sequential dependencies exist under this schedule, including the partial dependence of the length of any given IRT on the length of the preceding IRT. The sequential analysis also served to extend the finding in the literature, based on frequency distributions, that the likelihood of a reinforced IRT is greater after a reinforced IRT than a non-reinforced IRT. Rapid extinction and reconditioning were obtained.     

Solution of the intermediate size problem by pigeons

Pigeons learned to respond to the middle-sized member (S^D) of a set of three simultaneously presented stimuli with responses to the S^D reinforced on a VI 1 schedule. They were then tested for several days with other sets of three stimuli. One procedure presented reinforcements on a VI 1 schedule during the test independent of the stimulus chosen when a reinforcement was programmed. The tests were also given under extinction conditions. With the testing carried out with extinction, preference consistently was for the test stimulus most similar in physical size to the S^D. However, when the tests were with reinforcement, random responding resulted. Another effect of testing with reinforcement was an increase in incorrect responding with the training set. Such a test procedure was unsatisfactory for determining the effective aspect of the S^D. The conclusion, based on the data of the extinction series, was that pigeons learned the intermediate size problem on the basis of the discrimination of absolute stimulus properties.     

Escape behavior under continuous reinforcement as a function of aversive light intensity

In 11 male albino rats, lever-pressing responses, maintained under a CRF escape schedule with light as the aversive stimulus, were examined at each of five intensities, viz., 2.5, 18, 105, 190, and 386 ft-C. The function relating reciprocal of latency of the escape response to aversive light intensity passed through a maximum.     

Development of behavioral compensation to the effects of scopolamine during fixed-interval reinforcement

Rats were injected with scopolamine before every daily session of water reinforcement on a fixed-interval (FI) schedule. Initially the drug decreased the rate of responding. Control injections of scopolamine following each session did not. Over 119 sessions, the typical FI performance developed more slowly in the animals drugged before the sessions. Their rates of responding increased from session to session, to a level slightly greater than that of the animals drugged after the sessions. Their rates did not increase. The effects of injections before the session were not duplicated by increasing the deprivation of animals drugged after the session.