Oral self-administration of pentobarbital by rhesus monkeys: maintenance of behavior by different concurrently available volumes of drug solution.

For 4 rhesus monkeys, mouth-contact responses with either of two brass spouts were reinforced according to fixed-ratio schedules by 0.65-mL liquid deliveries during daily 3-hr sessions. Three experiments were conducted. In each experiment, independent fixed-ratio schedules were concurrently in effect at the two spouts. Following completion of each fixed ratio on a spout, a specified number of liquid deliveries were available from that spout under a continuous-reinforcement schedule. The number of such deliveries available at each spout was manipulated independently. In Experiment 1, a 1-mg/mL pentobarbital solution was simultaneously available with water (the drug vehicle) under concurrent fixed-ratio schedules of 32 responses for 3 subjects and 64 responses for the remaining subject. The number (N) of liquid deliveries that were available after completion of each fixed ratio was varied in the following order: 8, 4, 2, 1, and 8 (retest). For each subject at each condition, drug maintained more responding than water. The number of drug deliveries obtained per session was directly related to the amount of drug available per fixed ratio (i.e., to N), whereas the number of fixed ratios completed per session generally was inversely related to the value of N. In Experiment 2, fixed-ratio size was the same for each subject as in Experiment 1, but deliveries of a 1-mg/mL pentobarbital solution were available at both spouts. The number of drug deliveries available under one fixed-ratio schedule (Ns, the "standard" reinforcer amount) was held at eight, and the number of drug deliveries available under the second schedule (Nc, the "comparison" reinforcer amount) was changed across blocks of six sessions of stable responding in the following order: 1, 2, 4, 8, 4, 2, and 1. The identical series of comparison reinforcer amounts (Nc) was then tested twice more, but with the standard reinforcer (Ns) held first at four and then at two deliveries. Across the three choice series, reinforcing effects were directly related to reinforcer magnitude. In Experiment 3, deliveries of a 1-mg/mL pentobarbital solution again were available at both spouts. However, the two reinforcer amounts were held constant at N = 8 deliveries under one schedule and N = 4 deliveries under the second schedule, and fixed-ratio size was systematically varied. Across the range of fixed-ratio sizes from low to high, the degree to which behavior was better maintained by the larger of the two drug quantities was an inverted U-shaped function of fixed-ratio size.(ABSTRACT TRUNCATED AT 400 WORDS)     

EVALUATION OF REINFORCER PREFERENCES FOR PROFOUNDLY HANDICAPPED STUDENTS

Five students classified as profoundly/multiply handicapped were trained to use microswitches to indicate reinforcer preferences. The students were trained to emit a designated motoric response (raise arm or raise head) which in turn activated a microswitch. The microswitches were connected to battery-operated toys and devices, and served to provide immediate, contingent consequences tothe students for their motoric responding. The results of the investigation were evaluated within a multiple baseline (across students) with alternating treatments (potential reinforcers) design. During baseline, the students were provided withthe switches and devices, butthe switches were not connected tothe devices. Duringthe training conditions, the switches activatedthe devices. Evaluation of the devices was conducted by recordingthe cumulative frequency and duration of the students' responses. Whenthe microswitches activatedthe devices during training, a substantial increase inthe duration of motoric responding occurred for all students. In addition, some students performed differentially across devices, suggesting that they had reinforcer preferences.     

Authoritarianism,Anger, and Hostile Attribution Bias: A Test of Affect Displacement

Past research has supported the hypothesis that the relationship between harsh childhood punishment and adult political attitudes is due to the displacement of negative emotions that arise onto punitive public policies, e.g., support for the death penalty (Milburn, Conrad, Sala, & Carberry, 1995). Cognitions associated with childhood punishment may also impact adult political attitudes, yet their effects have not yet been examined, despite research that shows that punitive childhood experiences increase the tendency to attribute hostility to others. Thus, we investigated whether the tendency to make hostile attributions about others' behavior influences a person's authoritarianism, controlling for their parents' political orientation. Respondents completed an online survey concerning their childhood punishment experiences, their parents' political orientation, their trait anger, their level of hostile attribution bias (HAB), and their authoritarianism. Multiple regression analyses and structural equation modeling (SEM) found that higher childhood punishment has a significant direct effect on higher levels of authoritarianism, even after controlling for parents' political orientation, and that trait anger and HAB appear to mediate the effects of childhood punishment experiences on authoritarianism,. These results support the process of affect displacement as an important influence on adult punitiveness and political orientation.     

ON THE RELATION BETWEEN REINFORCER EFFICACY AND PREFERENCE

Most research on stimulus preference and reinforcer assessment involves a preference assessment that is followed by a reinforcer assessment. Typically, the most and least preferred stimuli are tested as reinforcers. In the current study, we first quantified the reinforcing efficacies of six food items and then assessed relative preference for each item. Relative preference ranking and reinforcer efficacies showed almost perfect concordance for 1 participant and partial concordance for the other. Discordance tended to occur with the weakest reinforcers.     

Delay discounting of qualitatively different reinforcers in rats

Humans discount larger delayed rewards less steeply than smaller rewards, whereas no such magnitude effect has been observed in rats (and pigeons). It remains possible that rats' discounting is sensitive to differences in the quality of the delayed reinforcer even though it is not sensitive to amount. To evaluate this possibility, Experiment 1 examined discounting of qualitatively different food reinforcers: highly preferred versus nonpreferred food pellets. Similarly, Experiment 2 examined discounting of highly preferred versus nonpreferred liquid reinforcers. In both experiments, an adjusting-amount procedure was used to determine the amount of immediate reinforcer that was judged to be of equal subjective value to the delayed reinforcer. The amount and quality of the delayed reinforcer were varied across conditions. Discounting was well described by a hyperbolic function, but no systematic effects of the quantity or the quality of the delayed reinforcer were observed.