William Timberlake

Auto-Shaping in Rats to the Presentation of Another Rat Predicting Food

Rats direct social rather than eating behavior toward a stimulus rat that predicts the imminent delivery offood. This result suggests that a predictive stimulus does not become a substitutefor a reward, but its characteristics elicit and support a particular subset of the responses commonly related to that reward. them to approach and eat rapidly from the food tray when food was delivered. On the third day of pretraining, each subject received 30 10-second presentations of the stimulus rat. No food was delivered on this day. After the 11 acquisition sessions, all subjects received eight extinction sessions during which the predictive stimulus was presented as in acquisition, but no food was delivered. The behavior of the subjects in the presence of the predictive stimulus was recorded by an observer using a coding scheme modified from Peterson (10) and Grant and Mackintosh (8). On each presentation of the predictive stimulus the observer noted several behaviors, including: Orient, Approach, Sniff, Bite, and Social Contact (paw, groom, crawl-over, and anogenital sniff) (11). A reliability check of this coding scheme with a naive observer produced an average interobserver reliability of .99. The four panels of Fig. I show the median percentage of trials on which each group of five animals performed behaviors in the different categories. The group data adequately reflect the scores of the individual subjects. Figure IA shows that the Cs+ animals successively increased the frequency of Orient, Approach, Sniff, and Social Contact during the I1-day acquisition period, and successively decreased the frequency of these behaviors during extinction. The incidence of Bite was zero over all trs. The CSS animals also engaged in considerable behavior directed toward the stimulus rat, but their performance stabilized at a lower level than that of the CS+ animals (see Fig. I B). Over the last 5 days of acquisition the median scores of the animals in each group showed no overlap in Social Contact, Approach, and Sniff, and only a single common score in the case of Orient. During extinction, the scores of the animals in the CS+ and CSS groups overlapped considerably. The CS+ animals showed greater diversity of social contact than did the CSS animals. Table I shows the median individual scores over the last five acquisition trials for paw, groom, crawl-over, and anogenital sniff. All five CS+ animals showed paw, groom, and crawl-over behaviors, and three showed anogenital sniff. Of the five CSS animals, three showed paw, two showed groom, and only one showed crawl-over and anogenital sniff. Video tapes of a randomly selected animal in each group showed additional social postures for the CS+ animal, such as sideways and head-over postures (8). In comparison to both the CS+ and CSS groups, the CSr groups showed a marked 4 inhibition of approach behavior during ac-4 14 NOVEMBER 1975 quisition (see Fig. IC). With one exception, the animals oriented on less than 10 percent of the trials and all animals remained by the food tray during the presentation of the stimulus rat. No animal ever engaged in Social Contact. During extinction all behaviors except Social Contact appeared to recover and increase toward overlap with the scores of the CSS group. The CSW group showed an increase in Orient equivalent to that of the CS+ group, but little increase in Approach or Sniff, and no Social Contact score (see Fig. 1 D). These results appear to reflect a low level of conditioning to the block of wood. The relative absence of Approach in this group shows that Approach to the predictive rat in the CS+ group was not based on its predictive value alone. Conditioned Approach

Behavior systems, associationism, and Pavlovian conditioning.

Associative and behavior systems accounts of Pavlovian conditioning have different emphases. The traditional associative account has focused on the role of the unconditional stimulus (US) in strengthening stimulus associations according to a set of general laws. The behavior systems account has focused on the relation of conditional responding to the preorganized perceptual, motor, and motivational organization engaged by the US. Knowledge of a behavior system enables successful prediction of the form and ease of conditioning as a function of the type of conditional stimulus (CS), US, and the CS-US relation. At the same time, Pavlovian manipulations act as a window on how a behavior system works. Both associative and behavior systems accounts can be criticized as incomplete and idiosyncratic. A comprehensive account of Pavlovian conditioning could profit from their integration.

Stimulus and response contingencies in the misbehavior of rats.

Misbehavior by rats, in the form of unnecessary and species-typical pawing, nosing, carrying, chewing, and retrieving a rolling ball bearing, was produced by pairing the ball bearing with food (Pavlovian procedure, Experiments 1 and 2) or by requiring contact with the ball bearing for food (operant procedure, Experiments 4 and 5). Misbehavior occurred both before and after eating the food pellet. The frequency, complexity, and duration of pre-pellet misbehavior was increased by delay of food until after the ball bearing exited (or was programmed to exit) and by requiring contact with the bearing to obtain food. Alternative goal-directed behavior, in the form of nosing, gnawing, and licking the food tray, occurred in Pavlovian contingencies in which food was delivered before the bearing was programmed to exit. Post-pellet misbehavior tended to occur when food was delivered before the bearing was programmed to exit and, in the case of required contact, before the animal released the bearing. Omission of food delivery on contact reduced the duration, complexity, and frequency of misbehavior, though experienced animals continued to contact (Experiment 3). In general, misbehavior was affected by both stimulus- and response-reward contingencies but showed characteristic organization and topography under both types of contingency.

Rats’ responses to a moving object related to food or water: A behavior-systems analysis

The present experiments compared rats’ responses to a moving object (a rolling ball bearing) related to either food or water under both Pavlovian and operant contingencies. In Experiment 1, food-restricted rats contacted food-related bearings more frequently and with more complex response patterns than water-restricted rats contacted water-related bearings. Food-related contacts occurred with shorter latency, longer average duration, and increased likelihood of dig, carry, and chew. Experiment 2 revealed that once contact with the bearing had been established, its form persisted despite changes in the type of reward and restriction. In Experiment 3, rats that were simultaneously food and water restricted learned to discriminate between painted and unpainted bearings related to food versus no food, water versus no water, and food versus water. Again, food-related bearings produced more complex, although not more frequent, interactions than did water-related bearings. In none of the experiments did rats lick the ball bearing related to water. The results supported a behavior-system approach, but not the stimulus-substitution or arbitrary-operant accounts of conditioned-response topography.

Regulation during challenge: A general model of learned performance under schedule constraint.

This article develops a general behavior-regulation model of learned performance related to the equilibrium approach of Timberlake ( 1980) and Timberlake and Allison ( 1974). The model is based on four assumptions: (a) Both the instrumental and contingent responses are regulated with respect to their own set point~; (b) these set points can be measured in a free baseline when both responses are relatively unconstrained and simultaneously available; (c) a reinforcement schedule can be seen as a constraint function that cross-couples the environmental effects of regulatory systems underlying the instrumental and contingent responses, thereby challenging their set points; and (d) molar behavior change under a schedule represents a compromise between the deviations from set points forced by the constraint function. These assumptions are translated into a set of coupled differential equations describing two regulatory systems related by a schedule. After providing an exact solution for this model, we derive as special cases two current alternative models of learned performance (Allison, 1976; Staddon, 1979). Finally, we demonstrate that the model is consistent in form with data from a variety of simple schedules.

Unpredicted food produces a mode of behavior that affects rats' subsequent reactions to a conditioned stimulus: A behavior-system approach to "context blocking"

The present experiments explored the relation between a mode of behavior produced by unpredicted presentations of an unconditioned stimulus (US) and subsequent interference with responding to a conditioned stimulus (CS) (the context-blocking effect). The US was food, the CS was a moving ball bearing, and the subjects were rats. The typical response to a moving bearing that predicts food is predatory interaction, and the behaviors that developed under unpredicted US presentations involved focused search and waiting oriented to the food tray. Experiment 1 manipulated the number of unpredicted food presentations and showed that the reduction in subsequent bearing contacts was more clearly related to the occurrence of initial food-tray behavior than to the number of prior food presentations. Experiments 2 and 3 manipulated the conditioning of food-tray behavior while holding constant the number of prior food presentations, and again showed a strong inverse relationship between initial food-tray behavior and ball-bearing contact. The latter experiments also indicated that the locus of interference with bearing-directed behavior was neither primarily central (associative or attentional) nor peripheral (motor interference), but resulted from the incompatibility of two modes of food-getting behavior, a more general predatory search mode versus a mode of focal search and waiting. A behavior-system account of these results does not preclude an associative basis for context-blocking effects, but it argues that such effects may occur at several levels and must function within appetitive structures underlying the animal’s food-getting behavior.

Winning isn't everything rats need only food deprivation and not food reward to efficiently traverse a radial arm maze

Abstract The present study examined the assumption that immediate food reward is the critical determinant of efficient performance on the radial maze. Food-deprived and nondeprived rats were run on a large-platformed, 8-arm radial maze that was either baited or unbaited. Food-deprived rats that were rewarded entered significantly more novel arms in their first eight choices than expected by chance, consistently ran to the ends of chosen arms, and increasingly chose adjacent arms over trials. Food-deprived rats that were unrewarded behaved in much the same way. In contrast, rats that were nondeprived and unrewarded did not choose novel arms at above chance levels, infrequently ran to the ends of chosen arms, and did not develop a consistent response strategy. Explanations of the development of organized behavior based on reinforcement, win-shift tendencies, or spontaneous alternation do not account for these results. Rats appear to have foraging strategies based on preorganized stimulus sensitivities and response dispositions that are readily engaged by food deprivation and result in efficient traversal of a radial maze even in the absence of food reward.

Reinforcement in Applied Settings: Figuring Out Ahead of Time What Will Work

This article reviews the practical value of conceptual attempts to specify the circumstances of reinforcement ahead of time. Improvements are traced from the transituational-reinforcer approach of Meehl (1950), through the probability-differential model of Premack (1959, 1965), to the response deprivation and disequilibrium approach (Timberlake, 1980, 1984; Timberlake & Allison, 1974). The application value of each approach is evaluated on the grounds of simplicity, accuracy, and adaptability. The article shows that the disequilibrium approach accounts for and extends current empirically driven techniques of reinforcement control and examines some of its limitations. The disequilibrium approach clarifies how current knowledge can be used to predict more accurately the circumstances of reinforcement and invites the collaboration of applied and basic research in its further development.

Schedule constraint on the average drink burst and the regulation of wheel running and drinking in rats.

Two experiments compared predictions of a molar-pattern model and a general molar behavior regulation model by requiring rats to wheel run for access to water. In both experiments schedule parameters constrained the baseline average burst length of drinking without constraining total drinking. Five levels of schedule constraint were imposed on time spent per drinking burst (Experiment 1) or the number of drinks per burst (Experiment 2). The results of both experiments supported the general molar behavior regulation view but not the molar-pattern model by showing no increase in total wheel running and no decrease in total drinking under schedule constraint. However, both experiments also showed local effects of drink burst constraint, including a direct relation between the degree of constraint and the local rate of drinking, and an approximation of the temporal distribution of baseline drinking under all degrees of schedule constraint. Most local changes support the view that rats defend the baseline temporal distribution of responding under schedule constraint, though some changes appear related to disruption of local response pattern characteristics.

System-Specific Differences in Behavior Regulation: Overrunning and Underdrinking in Molar Nondepriving Schedules

In two experiments we tested the molar regulation prediction that animals adjust schedule performance to reduce deviations from baseline response totals. Both experiments constrained the baseline drink-burst length under molar nondepriving schedules but allowed rats to continue running without drinking. In Experiment 1, rats were required to run in order to drink. In Experiment 2, water was delivered independently of running by fixed-time (FT) schedules. Under the run-to-drink contingency, rats exceeded their baseline amounts of running (overrunning) but failed to maintain their baseline water intake (underdrinking). The total amount of running that did not lead to drinking approximated baseline running. Under the FT schedules, rats again underdrank, but total running approximated baseline. These results do not support previous studies that have shown molar equilibrium effects under nondepriving reciprocal schedules. We conclude that (a) contingent running may not substitute for independent running; (b) intermittent access to water reduces the total instigation for drinking; (c) molar regulation differs under reciprocal and nonreciprocal schedules; and (d) more dynamic, system-specific regulatory models need to be developed.