This research examined three explanations for the "superstitious" behavior of pigeons under frequent fixed-time delivery of food: accidental response-reward contingency, stimulus substitution, and elicited species-typical appetitive behavior. The behavior observed in these studies consisted of occasional postfood locomotion away from the food hopper, and a predominant pattern of activity directed toward the hopper wall (wall-directed behavior), including approaching, stepping side to side, scratching with the feet, bumping with the breast, pendulum movements of the extended neck, and head bobbing, though not pecking. The consistency of these behavior patterns argued against explanation by accidental response contingencies, and the complexity of behavior was incompatible with the classic stimulus-substitution account. These studies also showed that: (1) response contingencies and prior stimulus experience can modify wall-directed behavior, but within definable limits; (2) pecking sometimes can be obtained in birds of specific strains, and by providing extended training; (3) placing the hopper in the floor at the center of a large chamber replaces wall-directed behavior with circling in a manner that resembles ground foraging for food. We conclude that superstitious behavior under periodic delivery of food probably develops from components of species-typical patterns of appetitive behavior related to feeding. These patterns are elicited by a combination of frequent food presentations and the supporting stimuli present in the environment.Key words: superstitious behavior, appetitive behavior, behavior systems, stimulus substitution, fixed-time schedules, wall-directed behavior, pecking, pigeons When pigeons receive food at frequent fixed times independent of their behavior, they rapidly develop a set of relatively stereotyped responses. These responses are typically described as "superstitious" because they emerge in the absence of actual environmental contingencies, presumably like superstitious behavior in humans (Skinner, 1948). The point of the present studies was to explore the form and causation of such behavior in pigeons. We will use the term superstitious (without quotes) to refer to behavior that emerges under a response-independent schedule, but without presumption as to its causation.The two predominant explanations of superstitious behavior in pigeons are the acci-

An important tenet of optimal foraging theory is that foragers compare prey densities in alternative patches to determine an optimal distribution of foraging behavior over time. A critical question is over what time period (time horizon) this integration of information and behavior occurs. Recent research has indicated that rats do not compare food density in a depleting patch with that in a rich patch delayed by an hour or more (Timberlake, 1984). In the present research we attempted to specify over what time period a future rich patch would affect current foraging. The effect of future food was measured by early entry into the rich patch (anticipation) and by a decrease in food obtained in the depleting patch (suppression). The rats showed anticipation of a rich patch up to an hour distant, but suppressed current feeding only if the rich patch was 16 min distant or less. The suppression effect appeared mediated by competition for expression between anticipatory entries into the rich patch and continued foraging in the depleting patch. These results suggest that optimal foraging is based on a variety of specific mechanisms rather than a general optimizing algorithm with a single time horizon.

In 2 experiments, access to a 0.15% saccharin solution was followed on alternating days by access to a 32% sucrose solution and the same saccharin solution. In Experiment 1, rats increased both intake of and preference for a flavored saccharin solution that predicted sucrose, but neither effect was found using a predictive odor cue alone. Experiment 2 replicated the predictive flavor results but showed suppression of saccharin intake when environmental cues predicted sucrose. When both flavor and environment predicted sucrose, saccharin intake did not change, but preference for the predictive flavor increased. Discriminative taste cues appear to facilitate the development of preference conditioning, but environmental cues favor negative anticipatory contrast effects. Also, preference conditioning and contrast may develop concurrently and compete for expression.

In three experiments, the time horizon over which the rat evaluates alternative feeding sources was investigated. The time horizon was measured by the suppression of intake of one incentive (a 0.15% saccharin solution) when a preferred alternative incentive (a 32% sucrose solution) was available but delayed. In Experiment 1, we found a direct function between the amount of saccharin intake and the delay time before access to 32% sucrose. Compared with intake for a saccharin-only control, saccharin intake was suppressed before 4-min and 16-min sucrose delays, but not before a 32-min delay. Because previous work (Flaherty & Checke, 1982) had reported suppression before a delay of nearly 32 min, in the subsequent experiments we examined factors that might account for this difference. In Experiment 2, we found that saccharin intake was suppressed before a 32-min delay interval when saccharin and sucrose solutions were presented in a bright-novel test environment but not when the same solutions were presented in the home cage. In Experiment 3, we found that the time between testing and subsequent postsession feeding could also affect the suppression of saccharin intake. Saccharin intake was suppressed when access to 32% sucrose was delayed by 32 min and the test situation was followed by immediate postsession feeding, but not when postsession feeding was delayed by 90 min. These results thus extend estimates of the rat's time horizon to at least 32 min, but indicate that the effective time horizon can vary, depending on the test situation.A critical question for understanding an animal's foraging behavior involves the period of time over which resources are evaluated as alternatives. This time period has been termed the time horizon of the animal (Kamil & Roitblat, 1985;Lea, 1981). The time horizon question is particularly important for theories of optimal foraging (see Pyke, Pulliam, & Charnov, 1977), because it represents the temporal limits within which an animal can be expected to optimize behavior. Recently, we reported data that placed the rat's time horizon around 16 min (Timberlake, Gawley, & Lucas, 1987). This estimate was obtained by providing rats with access to an increasingly costly (i.e., a depleting) patch, which was followed, after a delay, by access to an abundant patch with minimal cost. The rats suppressed their food intake in the depleting patch only when the less costly patch was delayed by 16 min or less.The aim of the present study was to determine the generality of our previous results by using a different procedure to estimate the rat's time horizon. It may be that the response costs related to a food are evaluated across a time frame different from that for the evaluation of food quality (e.g., its hedonic or caloric value). Some evidence for this possibility has been provided by Flaherty and Checke This research was supported by National Institute of Health Grant MH37892. We wish to thank Carey Jones and Dean Wallace for help in collecting data. The authors' mailing address is: Psychology ...

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.