Multiple and concurrent schedule performance: independence from concurrent and successive schedule contexts

Six pigeons were trained on multiple variable-interval schedules and performance was measured in the presence or absence of another variable-interval schedule (the common schedule) arranged concurrently with both components. Manipulations included varying the rate of reinforcement on the common schedule, leaving the common schedule unchanged while the components of the multiple schedule were varied, varying the multiple schedule components in the absence of the common schedule, and varying one component of the multiple schedule while the other component and the common schedule were unchanged. The normal rate-increasing and rate-decreasing effects of reinforcement rate increase were found, except that changing one multiple schedule component did not affect the response rate in the successively available common schedule component. Both concurrent and multiple schedule performance undermatched obtained reinforcement-rate ratios, but the degree of undermatching in multiple schedules was reliably greater. Allocation of responses between multiple schedule components was unaffected by the concurrent availability of reinforcement, and allocation of responses between concurrent schedules was unaffected by the successive availability of different reinforcement rates.     

Drug effects in squirrel monkeys trained on a multiple schedule with a punishment contingency

The behavior of four monkeys trained on a multiple schedule was differentially sensitive to selected pharmacological agents. The three components of the multiple schedule were: (1) a variable-interval schedule in which responses were reinforced on the average of once per minute; (2) a concurrent schedule in which every tenth response was reinforced and every fifteenth response, on the average, was shocked; and, (3) a neutral stimulus in the presence of which responses were neither reinforced nor shocked. Pentobarbital, chlordiazepoxide, and meprobamate increased responding during each of the components. Scopolamine and d-amphetamine decreased variable-interval performance, had minimal effects on performance during the concurrent-schedule component, and increased responding in the presence of the neutral stimulus. Chlorpromazine decreased variable-interval responding and had slight effects on the responding during the other two components.     

Multiple baseline investigation of stimulus functions in an FR chained schedule,

The performance of pigeons was studied on a multiple schedule in which a three-member FR chained schedule alternated with a three-member FR tandem schedule. The chain and tandem schedules contained identical response requirements. In the chained schedule, more pausing and lower response rates occurred in the first and second components than occurred in the tandem control, in which the same exteroceptive stimulus was associated with all components. Because the reinforcement and response contingencies were identical in the chain and tandem schedules, differences in performances can be attributed to stimulus control.     

Fixed-ratio punishment

Responses were maintained by a variable-interval schedule of food reinforcement. At the same time, punishment was delivered following every nth response (fixed-ratio punishment). The introduction of fixed-ratio punishment produced an initial phase during which the emission of responses was positively accelerated between punishments. Eventually, the degree of positive acceleration was reduced and a uniform but reduced rate of responding emerged. Large changes in the over-all level of responding were produced by the intensity of punishment, the value of the punishment ratio, and the level of food deprivation. The uniformity of response rate between punishments was invariant in spite of these changes in over-all rate and contrary to some plausible a priori theoretical considerations. Fixed-ratio punishment also produced phenomena previously observed under continuous punishment: warm-up effect and a compensatory increase. This type of intermittent punishment produced less rapid and less complete suppression than did continuous punishment.     

Fixed-interval punishment

The average rate of bar-pressing maintained by a variable-interval schedule of milk reinforcement in 33 rats was found to be a decreasing function of intensity of concurrent punishment and, over a wide range of shock intensities, was inversely related to punishment frequency. Cumulative records were, however, negatively accelerated during 30-min punishment sessions with complete suppression occurring earlier and earlier (after fewer and fewer shocks) as intensity increased. In addition, acceleration was often observed between successive fixed-interval shock presentations and, at low and moderate intensities, bursts of responding occurred after each shock. The time to recover between punishment sessions (post-punishment recovery) was an increasing monotonic function of punishment intensity.     

Conditioned punishment

Responses of pigeons were maintained by a VI schedule of food reinforcement. Conditioned punishment was programmed by having these responses concurrently produce an originally neutral stimulus. The effectiveness of this response-contingent stimulus was maintained by infrequent and prearranged stimulus-shock pairings delivered independently of responses. This conditioned punishment procedure reduced the overall response rate as long as the procedure was in effect. The extent and durability of the reduction was a function of the intensity of the shock that was paired with the stimulus. Analysis of the reduction in the overall response rate revealed: (1) a reduction of responses occurring in the absence of the response-contingent stimulus, which was designated as a “punishing” effect, and (2) a reduction of responses during the response-contingent stimulus, which was designated as a “suppressive” effect.     

Schedules using noxious stimuli. I. Multiple fixed-ratio and fixed-interval termination of schedule complexes

The termination of a schedule complex, comprising a stimulus in the presence of which brief presentations of electric shocks are scheduled, is a reinforcer. Conditions were studied under which schedule-controlled patterns of responding characteristic of fixed-interval, fixed-ratio, and multiple fixed-interval fixed-ratio schedules can be maintained in the squirrel monkey by terminating a schedule complex. The schedule of shock presentation was a critical determinant of the patterns of responding, especially under fixed-interval schedules of termination. The rates and patterns of responding under various schedules of termination of schedule complexes were generally akin to those maintained under comparable schedules of food presentation. The findings suggest a general similarity in the dynamic aspects of performances under schedules of schedule-complex termination and comparable schedules of food presentation. The schedule of reinforcement is more important than the nature of the reinforcer in the control of behavior.     

Commitment using punishment.

Experimental parameters were adjusted so that pigeons' pairwise choices among three alternatives reflected the following order of preference: (a) a smaller-sooner reinforcer, (b) a larger-later reinforcer, and (c) the smaller-sooner reinforcer followed by a punishment (consisting of an extended blackout period). After this order of preference was established, the pigeons were exposed to a two-link, concurrent-chain-like choice procedure. One terminal link consisted of a choice between the smaller-sooner and the larger-later reinforcer; the other terminal link was identical to the first except that the smaller-sooner reinforcer was followed by blackout punishment. The pigeons' preference (in their initial-link choice) for the terminal link with the punished smaller-sooner alternative increased as the delay between the initial and terminal links increased. By choosing this terminal link, the pigeons are said to have "committed" themselves to obtaining the larger-later reinforcer. However, unlike prior studies of commitment (e.g., Rachlin & Green, 1972), it was still possible after making the commitment for the pigeons to choose the smaller-sooner reinforcer and undergo the punishment. The pigeons did in fact occasionally make this highly deleterious choice.     

Summation of punishment suppression

In two experiments, eight rats were trained to lever press with food on a variable-interval schedule. Bar pressing produced shock on a variable-interval schedule in the presence of two independently presented stimuli, a light and a tone. Two rats in each experiment received alternative presentations of the light and the tone and were consequently always in the presence of a stimulus that signalled variable-interval punishment. The other two rats in each experiment were treated similarly except that they received periods in which neither light nor tone was present. During these periods, bar pressing was not punished. The two stimuli that signalled punishment were then presented simultaneously to evaluate the effect of stimulus compounding on response suppression. The subjects trained without punishment-free periods did not show summation to the compound stimulus; the subjects trained with punishment-free periods showed summation of suppression. The major difference between the two experiments was the longer mean interval of variable-interval punishment used in the second experiment. This manipulation made the summation effect more resistant to extinction and thus increased its magnitude.     

利他性惩罚的动机

社会规范的维系离不开对违规者实施的利他性惩罚, 然而, 从个体心理层面来看, 利他性惩罚的动机却并不是全然利他的。除了积极维护公平原则以外, 追求良好声誉、规避潜在损失或消除负性情绪也在不同程度上驱动了利他性惩罚。此外, 对惩罚成本数量和成本形式的敏感也表明基于成本-收益原则的策略性动机在驱动利他性惩罚中占据一席之地。进一步探索在利他性惩罚实施过程中不同动机之间的相互作用是未来的重要研究方向。     

Resistance to punishment as a function of intensity and frequency of prior punishment experience

Rats with a history of intermittent punishment have been found to persist in the face of continuous punishment. It was predicted from an extension of frustration theory to punishment that increasing the intensity or frequency of intermittent punishment would increase persistence to high fear elicited by continuous punishment. Two experiments, employing 310 rats, verified this prediction for both intensity and frequency manipulations but indicated rather narrow boundary conditions for their effects.