Deprivation and satiation: The interrelations between food and wheel running

Two experiments were designed to assess whether depriving rats of food would increase the reinforcement effectiveness of wheel running (Experiment 1) and whether satiation for wheel running would decrease the reinforcement effectiveness of food (Experiment 2). In Experiment 1, a progressive-ratio schedule was used to measure the reinforcement effectiveness of wheel running when rats were deprived or not deprived of food. Completion of a fixed number of lever presses released a brake on a running wheel for 60 s, and the response requirement was systematically increased until the rat stopped pressing or until 8 hr had elapsed. The ratio value reached (and the total number of lever presses) was an inverted-U function of food deprivation (percentage body weight). In Experiment 2, when wheel running preceded test sessions, fewer food-reinforced lever presses were maintained by the progressive-ratio schedule, and responding occurred at a lower rate on a variable-interval schedule. An interpretation of these results is that deprivation or satiation with respect to one event (such as food) alters the reinforcement effectiveness of a different event (such as access to wheel running).     

Effectiveness of social reinforcement as a function of contingent and noncontingent satiation

The social satiation effect is the inverse relation between the availability of a social stimulus and its subsequent efficacy in a reinforcing role. According to a suggested cognitive-interactive theory, the satiation effect is mediated by children's attributions of contingency between their own behavior and the experimenter's actions in the satiation treatments. Perceived contingencies depend, at least to an extent, on actual contingencies, and it was therefore predicted that a satiation effect would be observed only for groups presented in the satiation treatment with noncontingent social stimuli but not for groups presented with contingent stimuli. Middle-class 5- and 7-year-old children were subjected to a 10-min waiting period in which the stimulus word “Yafeh” (“good” in English) was presented 2 or 20 times, contingently or noncontingently. They were then given a 75-trial binary discrimination test: correct responses were reinforced with “Yafeh”. The hypothesis was confirmed in the analysis of variance. However, the predicted difference between the slopes of the contingency and noncontingency conditions was found clearly only in the older sample, while the younger children were more influenced by the number of social stimuli presented in the treatment (satiation) and less influenced by the method of stimulus presentation.     

Implicit rewards as reinforcers and extinguishers

Previous studies of implicit reinforcement with children have presented the implicit reward phase after baseline conditions. The present study replicated this design and compared these effects within a design where implicit rewards were presented after direct rewards to both targets and peers. Thirty-two fourth grade children copied the letters of the alphabet under varying reward conditions. Data indicated the presence of reinforcement effects when presented after baseline, and extinction effects when presented after direct reward conditions.     

Self-presentation and drive in social facilitation

Social facilitation refers to cases in which the presence of others increases the probability of certain responses on the part of an independently operating individual. Drive theory attributes these effects to an unconscious facilitation of dominant responses, as defined by Hull-Spence learning theory. Self-presentation explanations posit changes in motivation and cognitive strategies that result from an increased concern with favorable private and public images. The present paper reviews evidence and presents an experiment indicating both points of view are valid, but that neither perspective by itself can account for all relevant data.     

Projector slide changing and focusing as operant reinforcers

Uninstructed subjects choose to view, in sharp focus where possible, projected visual images in preference to various simpler auditory and visual stimuli (e.g., buzzers of flashing lights). The rate of responding on the lever rapidly increased above the operant level (projector inoperative) even though the stimuli were nonsense syllables. When focusing also was made contingent on responses, the subjects promptly started sharpening the focus of legible but blurred nonsense syllables. When the visual material was colored landscape scenes, the rates of slide-changing generally decreased, because of increased viewing time relative to the nonsense syllables, at the same time that the latencies of focusing decreased. Both the sharpness of focus and the total time spent with the image in sharp focus increased greatly with the colored slides, establishing that the subjects were under control of the stimulus events. Extinction of both responses occurred very rapidly when the controls became inoperative.     

Deprivation and reward stimuli as compound stimuli

In Experiment 1 the experimental group was tested with a deprivation level and a reward magnitude which it had experienced previously but which it had not experienced in combination. This group was inferior in test performance to a group which had experienced the test deprivation-reward combination prior to test. These results were interpreted as indicating that deprivation stimuli and reward stimuli form a compound stimulus and training on the elements of the compound produces performance inferior to training directly on the compound. In Experiment 2, the decrement associated with two different shifts in deprivation and reward did not differ despite the different size change of total incentive involved in the two shifts. The results were interpreted as indicating that the deprivation-reward stimulus is not produced by a single underlying incentive mechanism.     

The role of social and material reinforcers in increasing talking of a disadvantaged preschool child

Adult social reinforcement and access to materials in the preschool were made contingent on the verbalizations of a 4-yr-old Negro girl with an extremely low frequency of talking. Though the teachers' social attention was always given immediately for all spontaneous speech, if the child's spontaneous verbalizations were requests for materials, those materials were withheld until she had responded to the teachers' questions about those materials. When she was silent, the teachers withheld their attention and the materials. A high frequency of verbal behavior was quickly established. When both teacher attention and materials were provided only when the child was not verbalizing, the child's frequency of talking immediately decreased. When social attention and materials were again made contingent upon spontaneous speech and answering questions, the child's frequency of talking quickly increased to its previous high level. The content of the child's verbal behavior which increased was primarily a repetition of requests to the teachers with little change noted in the non-request verbalizations, or verbalizations to other children. A further experimental analysis demonstrated that social interaction per se was not the reinforcer which maintained the increased verbalization; rather, for this child, the material reinforcers which accompanied the social interaction appeared to be the effective components of teacher attention.     

Nest material and food as reinforcers for fixed-ratio responding in mice

Three experiments investigated the importance of operant-reinforcer distance as a factor affecting continuous reinforcement (CRF) and fixed-ratio (FR) performance in mice, with nest material and food as reinforcers. In Experiment 1, nest material (paper strips) was presented on a series of FR schedules of increasing size, with the operandum located as close as possible to the reinforcer dispenser. Subjects compensated for increases in FR size by proportionately increasing their response output, but ratio strain occurred at low FR values. In Experiment 2, response rate was found to be inversely related to operant-reinforcer distance on a CRF schedule with nest material as reinforcer. In Experiment 3, food was presented on a series of FR schedules at two levels of deprivation, and with three operant-reinforcer distances. Operant-reinforcer distance was found to affect CRF response rate, degree of compensation for increases in FR size, and occurrence of ratio strain, but only when deprivation level was low. The results support the view that nest material and food share fundamentally similar reinforcing properties, but that nest material is a weaker reinforcer under normal test conditions.     

Food-paired stimuli as conditioned reinforcers: effects of d-amphetamine.

Seven pigeons were studied in two experiments in which key pecks were reinforced under a second-order schedule wherein satisfaction of variable-interval schedule requirements produced food or a brief stimulus. In the second part of each session, responses produced only the brief stimulus according to a variable-interval schedule (food extinction). For the 4 pigeons in Experiment 1, the response key was red throughout the session. In separate phases, the brief stimulus was either paired with food, not paired with food, or not presented during extinction. d-Amphetamine (0.3 to 10.0 mg/kg) dose-dependently reduced food-maintained responding during the first part of the session and, at intermediate dosages, increased responding during the extinction portion of the session. The magnitude of these increases, however, did not consistently depend on whether the brief stimulus was paired, not paired, or not presented. It was also true that under nondrug conditions, response rates during extinction did not differ reliably depending on pairing operations for the brief stimulus. In Experiment 2, 3 different pigeons responded under a procedure wherein the key was red in the component with food presentations and blue in the extinction component (i.e., multiple schedule). Again, d-amphetamine produced dose-related decreases in responding during the first part of a session and increases in responding in the second part of the session. These increases, however, were related to the pairing operations; larger increases were observed when the brief stimulus was paired with food than when it was not or when it was not presented at all. Under nondrug conditions, the paired brief stimulus controlled higher response rates during extinction than did a nonpaired stimulus or no stimulus. These findings suggest that d-amphetamine can enhance the efficacy of conditioned reinforcers, and that this effect may be more robust if conditioned reinforcers occur in the context of a signaled period of extinction.     

Resistance to satiation: Reinforcing effects of food and eating under satiation

It has been shown previously that rats which have learned a response when hungry will continue to make that response when tested satiated, a phenomenon labeled resistance to satiation. Here we showed that rats which were previously trained hungry will learn a new response for the opportunity to consume pellets in a new situation when tested satiated. In four experiments various groups received each of the components of the training given when rats learn an instrumental response when hungry. Rats were placed in the goalbox of a straight alley and given food pellets when hungry or were hungry only in their home cages prior to running a straight alley in the satiated test in Experiment 1. In Experiments 2, 3, and 4 learning of a differential conditioning problem for pellets in S+ (nonreward in S?) was measured in the satiated test. Groups given pellets in their home cages when hungry with or without alley exposure learned to run more rapidly in S+ than in S? in the satiated test phase. The tendency to eat pellets in the apparatus and the reinforcing effect of eating the pellets was larger for rats which ate the pellets when hungry in their home cage than for rats which ate the pellets when satiated in their home cage. Being hungry in the home cage with no pellets was not sufficient to produce eating or running for pellets in the satiated test, indicating that any inherent reinforcing effect of the pellets is not sufficient to produce eating or running, and that incomplete satiation cannot account for the learning. These data indicate that a reinforcing effect of eating pellets under satiation is an important determiner of resistance to satiation.     

Choice and number of reinforcers

Pigeons were exposed to the concurrent-chains procedure in two experiments designed to investigate the effects of unequal numbers of reinforcers on choice. In Experiment 1, the pigeons were indifferent between long and short durations of access to variable-interval schedules of equal reinforcement density, but preferred a short high-density terminal link over a longer, lower density terminal link, even though in both sets of comparisons there were many more reinforcers per cycle in the longer terminal link. In Experiment 2, the pigeons preferred five reinforcers, the first of which was available after 30 sec, over a single reinforcer available at 30 sec, but only when the local interval between successive reinforcers was short. The pigeons were indifferent when this local interval was sufficiently long. The pigeons' behavior appeared to be under the control of local terminal-link variables, such as the intervals to the first reinforcer and between successive reinforcers, and was not well described in terms of transformed delays of reinforcement or reductions in average delay to reinforcement.     

Choice and multiple reinforcers

Pigeons chose between equivalent two-component mixed and multiple terminal-link schedules of reinforcement in the concurrent-chains procedure. The pigeons preferred the multiple schedule over the mixed when the components of the compound schedules were differentiated in terms of density of reinforcement, but the pigeons were indifferent when the components were differentiated in terms of number of reinforcers per cycle. Taken together, these results indicate that a local variable, the interval to the first reinforcer, but not a molar variable, the number of reinforcers, was sufficient to differentiate the components and thereby evoke preference.