An extensive body of research using concurrent-chains schedules of reinforcement has shown that choice for one of two differentially valued food-associated stimuli is dependent upon the overall temporal context in which those stimuli are embedded. The present experiments examined whether the concurrent chains procedure was useful for the study of…

Choice procedures have indicated that the relative reinforcing effectiveness of opioid drugs increases during opioid withdrawal. The demand curve, an absolute measure of reinforcer value, has not been applied to this question. The present study assessed whether mild morphine withdrawal would increase demand for or choice of remifentanil or…

Delay to delivery of a reinforcer can decrease responding for that reinforcer and increase responding for smaller reinforcers that are available concurrently and delivered without delay; acute administration of drugs can alter responding for large, delayed reinforcers, although the impact of chronic treatment on delay discounting is not well…

The goal of this series of experiments was to develop an operant choice procedure to examine rapidly the punishing effects of intravenous drugs in rats. First, the cardiovascular effects of experimenter-administered intravenous histamine, a known aversive drug, were assessed to determine a biologically active dose range. Next, rats responded on…

For many years, it has been suggested that drugs that interfere with dopamine (DA) transmission alter the "rewarding" impact of primary reinforcers such as food. Research and theory related to the functions of mesolimbic DA are undergoing a substantial conceptual restructuring, with the traditional emphasis on hedonia and primary reward yielding…

Six rhesus monkeys responding under a three-component multiple schedule were administered haloperidol to determine its effects on cocaine self-administration and on cocaine's disruptive effects on the repeated acquisition and performance of response chains. In the absence of haloperidol, 0.0032 - 0.032 mg/kg/infusion of cocaine increased response…

Increases in rates of punished behavior by the administration of drugs with anxiolytic effects (called antipunishment effects) are well established in animals but not humans. The present study examined antipunishment effects of ethanol in humans using a choice procedure. The behavior of 5 participants was placed under six concurrent…

Tolerance to effects of cocaine can be modulated by schedules of reinforcement. With multiple ratio schedules, research has shown an inverse relationship between ratio requirement and amount of tolerance that resulted from daily administration of the drug. In contrast, tolerance to the effects of cocaine on behavior under multiple interval…

The generalized matching law provides precise descriptions of choice, but has not been used to characterize choice between different doses of drugs or different classes of drugs. The current study examined rhesus monkeys' drug self-administration choices between identical drug doses, different doses, different drugs (cocaine, remifentanil, and…

This experiment assessed the effects of "d"-Amphetamine and ethanol on reinforced variable and repetitive key-peck sequences in pigeons. Pigeons responded on two keys under a multiple schedule of Repeat and Vary components. In the Repeat component, completion of a target sequence of right, right, left, left resulted in food. In the Vary component,…

Given a commodity available at different prices, a unit-price account of choice predicts preference for the cheaper alternative. This experiment determined if rhesus monkeys preferred remifentanil (an ultra-short-acting [mu]-opioid agonist) delivered at a lower unit price over a higher-priced remifentanil alternative (Phases 1 and 3). Choice…

Daily administration of cocaine often results in the development of tolerance to its effects on responding maintained by fixed-ratio schedules. Such effects have been observed to be greater when the ratio value is small, whereas less or no tolerance has been observed at large ratio values. Similar schedule-parameter-dependent tolerance, however,…

Four rats responded under a "self-control" procedure designed to obtain delay- discount functions within sessions. Each session consisted of seven blocks, with seven trials within each block. Each block consisted of two initial forced- choice trials followed by five free-choice trials. On choice trials, the rats could press either of two…

The effects of two anorectic drugs, dexfenfluramine and phentermine, on food intake under different food-access conditions were examined. Experiment 1 compared the effects of these drugs on food intake under a progressive-ratio (PR) schedule and free-access conditions. Dexfenfluramine decreased food intake under both conditions, but the doses…

Three pigeons were trained to discriminate among 5 mg/kg pentobarbital, 2 mg/kg amphetamine, a combination of these two drugs at these doses, and saline using a four-choice procedure (amphetamine--pentobarbital group). Three other pigeons were trained to discriminate among 5 mg/kg morphine, 2 mg/kg methamphetamine, a combination of these two drugs…