Relations among equivalence, naming, and conflicting baseline control.

Three studies were conducted with different groups of 6 students each to explore the effects of training class-inconsistent relations and naming on demonstrations of emergent arbitrary stimulus relations. In all studies, two three-member equivalence classes of Greek symbols (A1B1C1 and A2B2C2) emerged as a result of training in conditional discriminations. Two new symbols were introduced (X and Y), and additional conditional discriminations were trained, whereby X was designated as the positive discriminative stimulus (S+) and Y was designated as the negative discriminative stimulus (S-) for A1 and B2. Conversely, Y was designated as the S+ and X as the S- for B1 and A2. This introduced conflicting sources of control within and between classes. In Study 1, subjects were not provided with names for the stimuli. In Study 2, the experimenter provided common names for the stimuli within each class. In Study 3, the subjects were required to use the common names during conditional discrimination training and test-trial blocks. In all experiments, equivalence responding with respect to the original classes was disrupted for some subjects subsequent to learning the new relations. Furthermore, in Studies 2 and 3, there were frequent examples of noncorrespondence between observed (listener or speaker) naming patterns and derived relations. These results support the view that demonstrations of equivalence are subject to control from a variety of sources rather than being fundamentally dependent on naming.

Effects of drugs on the temporal distribution of schedule-induced polydipsia in rats.

Drinking was induced in food-deprived rats by a fixed-time 1-min schedule of food presentation. With three rats, d-amphetamine (0.25, 0.5, 1.0, and 2.0 mg/kg) led to a dose-related increase in licking early in the interfood intervals, the peak of the temporal distribution of licking being shifted to earlier values. These effects were seen even when d-amphetamine had no effect on overall rates of licking and drinking. With another three rats, however, diazepam (0.5, 1.0, 2.0, and 4.0 mg/kg) did not shift the peak of the temporal distribution of licks in interfood intervals, even at doses that produced small increases in overall rates of licking and drinking. However, diazepam did reduce the peak of the distributions of licks at doses that did not decrease water intake and licks per minute.

Stimulus effects on concurrent performance in transition.

Six experimentally naive pigeons were exposed to concurrent variable-interval variable-interval schedules in a three-key procedure in which food reinforcement followed pecks on the side keys and pecks on the center key served as changeover responses. In Phase 1, 3 birds were exposed to 20 combinations of five variable-interval values, with each variable-interval value consistently associated with a different color on the side keys. Another 3 pigeons were exposed to the same 20 conditions, but with a more standard procedure that used a nondifferential discriminative stimulus on the two side keys throughout all conditions. In Phase 2, the differential and nondifferential stimulus conditions were reversed for each pigeon. Each condition lasted for one 5-hr session and one subsequent 1-hr session. In the last 14 conditions of each phase, the presence of differential discriminative stimuli decreased the time necessary for differential responding to develop and increased the sensitivity of behavior to reinforcement distribution in the 1st hr of training; during the last hours of training in each condition, however, the effects of the differential discriminative stimuli could not be distinguished from the effects of reinforcement distribution per se. These results show the importance of studying transitions in behavior as well as final performance. They may also be relevant to discrepancies in the results of previous experiments that have used nonhuman and human subjects.

Effects of d-amphetamine and of diazepam on non-punished and punished schedule-induced drinking in rats.

Drinking induced in food-deprived rats by a Fixed-Time 1min schedule of food presentation was measured by the amount of water consumed per session and the number of licks per inter-food interval. Subsequently each lick initiated a 10-sec signalled delay in the delivery of food, which led to a decrease in drinking (punishment). With three rats the effects of d-amphetamine (0.25, 0.5, 1.0, 2.0mg/kg) were assessed on non-punished and then on punished drinking. With another three rats, the effects of diazepam (0.5, 1.0, 2.0, 4.0mg/kg) were assessed. The smaller doses of d-amphetamine had no consistent effect on overall measures of non-punished schedule-induced drinking, but the largest dose decreased them. With the signalled delay d-amphetamine increased punished schedule-induced drinking. Non-punished drinking was increased by small doses of diazepam and decreased by the largest dose, but no dose of diazepam affected punished drinking.

B. F. Skinner and G. H. Mead: on biological science and social science.

Skinner's contributions to psychology provide a unique bridge between psychology conceptualized as a biological science and psychology conceptualized as a social science. Skinner focused on behavior as a naturally occurring biological phenomenon of interest in its own right, functionally related to surrounding events and, in particular (like phylogenesis), subject to selection by its consequences. This essentially biological orientation was further enhanced by Skinner's emphasis on the empirical foundations provided by laboratory-based experimental analyses of behavior, often with nonhuman subjects. Skinner's theoretical writings, however, also have affinity with the traditions of constructionist social science. The verbal behavior of humans is said to be subject, like other behavior, to functional analyses in terms of its environment, in this case its social context. Verbal behavior in turn makes it possible for us to relate to private events, a process that ultimately allows for the development of consciousness, which is thus said to be a social product. Such ideas make contact with aspects of G. H. Mead's social behaviorism and, perhaps of more contemporary impact in psychology, L. Vygotsky's general genetic law of cultural development. Failure to articulate both the biological and the social science aspects of Skinner's theoretical approach to psychology does a disservice to his unique contribution to a discipline that remains fragmented between two intellectual traditions.

The effects of signalled and unsignalled lick-dependent delays on the development of schedule-induced drinking in rats.

Food pellets were programmed to be delivered to rats every 60 sec (Fixed Time 60-sec schedule), and the development of schedule-induced drinking was measured in terms of the amount of water consumed and the number of licks per inter-pellet interval. For some rats (masters) 10-sec delays in food delivery were dependent on licks. Yoked-control rats received food at the same time as their masters and independently of their own behaviour. In Experiment 1, in which the delays were signalled by a blackout, the master rats began to drink, but this schedule-induced behaviour then decreased to levels lower than those shown by the yoked controls. When the signalled delays were discontinued, the drinking of the master rats recovered. In Experiment 2, in which the delays were not signalled, the master rats did not develop as much schedule-induced drinking as the yoked controls, and discontinuing the delays led to only small increases in drinking. These results support the view that schedule-induced drinking is subject to control by its consequences.

Punishment of schedule-induced drinking in rats by signaled and unsignaled delays in food presentation.

Food-deprived rats were exposed to a fixed-time 60-s schedule of food-pellet presentation and developed schedule-induced drinking. Using an ABA reversal design, three experiments investigated the effects of events then made dependent on licks. In Experiment 1, lick-dependent signaled delays (10 s) in food presentation in general led to decreased drinking, which recovered when the signaled delays were discontinued. The drinking of yoked-control rats, which received food at the same times as those exposed to the signaled-delay contingency, showed much smaller changes. Experiment 2 showed that 10-s lick-dependent signals alone did not reduce drinking. In Experiment 3, when licks produced unsignaled 10-s delays in food there were less marked and more gradual changes in drinking than in Experiment 1, although these effects again were greater than with yoked-control animals. We concluded that both signaled and unsignaled delays functioned as punishers of drinking. These findings support the view that schedule-induced drinking, like operant behavior, is subject to control by its consequences.

Effects of d-amphetamine and of beta-phenylethylamine on fixed interval responding maintained by self-regulated lateral hypothalamic stimulation in rats.

d-Amphetamine sulphate (0.25-4.0 mg/kg) and beta-phenylethylamine hydrochloride (1.25-50 mg/kg) respectively were administered IP to two groups of rats (R1-R4 and R5-R8 respectively) responding on a fixed interval (FI) schedule (R1-R4 FI 60 sec, R5-R8 FI 30 sec) of electrical hypothalamic stimulation. The duration of each train of stimulation was controlled by the duration of each lever press that initiated stimulation. Under these conditions administration of d-amphetamine resulted in a marked increase in overall response rates on the FI 60 sec schedule. This effect was significant at 1, 2 and 4 mg/kg. d-Amphetamine had not significant effect on the duration of hypothalamic stimulation or on the duration of responses occurring during the FI. Administration of beta-phenylethylamine resulted in a decrease in overall response rates on the FI 30 sec schedule. This effect was significant at 50 mg/kg. beta-Phenylethylamine increased the duration of responses occurring during the FI, this effect being significant at 25 and 50 mg/kg, but had no significant effect on the duration of hypothalamic stimulation. These results indicate that the systemic effects of d-amphetamine on response rate, and of beta-phenylethylamine on both response rate and response duration, are dissociable from changes in the self-regulated duration of lateral hypothalamic stimulation.

Effects of chlordiazepoxide on the self-regulated duration of lateral hypothalamic stimulation in rats.

Rats were exposed to a fixed-interval 60-s schedule under which responding was maintained by electrical stimulation of the lateral hypothalamus. The duration of stimulation was controlled by the duration of each lever press that initiated reinforcement. The effects of variation in current intensity and administration of several chlordiazepoxide (CDP) doses (2.5--20 mg/kg IP) were investigated. The duration of stimulation was inversely related to current intensity. Administration of CDP resulted in increases in response rate and the durations of reinforced and non-reinforced responses. CDP increased the response duration reliably more with non-reinforced responses than with responses that served to regulate the duration of stimulation. Thus CDP-induced increases in the duration of brain stimulation with the single lever self-regulation procedure may not be attributed to a specific effect of this compound on neural processes underlying reinforcement. The present results indicate the utility of intermittent schedules in establishing the specificity of drug effects on self-regulated duration of brain stimulation in the single-lever condition.

The effects of pimozide and of reward omission on fixed-interval behavior of rats maintained by food and electrical brain stimulation.

Pimozide (0.125 to 2.0 mg/kg) was administered to rats whose behavior was maintained by a fixed-interval schedule in which the reward was either food (Experiment 1) or electrical stimulation of the brain (Experiment 2). The effects of the drug were compared with the effects of withholding reward (i.e., extinction) in both experiments. Reward omission and administration of pimozide both resulted in decreases in overall rates of responding and increases in the time taken by the subjects to complete a specified number of fixed-intervals. The typical patterning of responding during the sessions of reward omission was also characteristic of the effects of pimozide with food reward but not with brain stimulation reward. The duration of trains of brain stimulation which was under the control of the subjects in Experiment 2, was not altered by administration of pimozide. The differences between the effects of pimozide on behavior maintained by intermittent food reward or by intermittent brain stimulation reward limits a global interpretation of the effects of neuroleptics.

Polydipsia induced in rats by second-order schedules of reinforcement.

Three rats were exposed to a second-order schedule in which fixed-interval components ended either with food or with a brief stimulus that was never paired with food. Food and the brief stimulus occurred in a random sequence (variable-ratio 2 overall schedule). Another three rats were exposed to a similar second-order schedule, the only difference being that the food or the stimulus was presented independently of operant behavior (fixed-time components). The three rats exposed to the fixed-interval components licked at a water spout after each food presentation. These rats also licked in the intervals after the brief stimulus. Although the discriminative properties of food and of the brief stimulus were identical in relation to subsequent reinforcement, licking after the stimulus was less than after food. The three rats exposed to the second-order schedules with fixed-time components also licked at the water spout after food, but these rats did not lick consistently after brief stimulus presentations.