Social reinforcement of operant behavior in rats: a methodological note.

An apparatus was developed to study social reinforcement in the rat. Four Long-Evans female rats were trained to press a lever via shaping, with the reinforcer being access to a castrated male rat. Responding under a fixed-ratio schedule and in extinction was also observed. Social access was found to be an effective reinforcer. When social reinforcement was compared with food reinforcement under similar conditions of deprivation and reinforcer duration, no significant differences were observed.     

Producing a change from competition to sharing: effects of large and adjusting response requirements

Pairs of high-school students matched-to-sample for money. On each trial, the first pair member to complete a fixed ratio of knob-pulling responses could work the matching problem on that trial. Competition occurred when both pair members responded for the problem. Sharing occurred when only one pair member responded on each trial, and the subjects alternated trials. Hence, sharing requires less responding and still allows a moderate number of reinforcers for each subject. Recent research has shown that increasing the response requirement to the point that it may have aversive properties will produce a change from competition to sharing. A related variable is an adjusting schedule that adjusts the subjects' response requirements so that their abilities to take reinforcers are equal. In this way, subjects might learn that competition requires more responding but produces no more reinforcers. However, recent research also suggests that competition decreases over sessions without experimental manipulations. Because of this possibility of a time-related variable, ratio size and an adjusting schedule were studied in a group design. Competition did decrease for all groups over sessions, but the large-ratio groups switched from competition to sharing sooner than the low-ratio groups. The adjusting schedule had a similar but smaller effect.     

Behavioral economics of drug self-administration. II. A unit-price analysis of cigarette smoking.

In behavioral economics, the ratio of response requirement to reinforcer magnitude is referred to as unit price. Previous research with nonhuman subjects has demonstrated that (a) comparable amounts of food are consumed at the same unit price even though different response requirements and reinforcer magnitudes comprise that unit price and (b) increases in unit price decrease food consumption in a positively decelerating fashion. The present study assessed the generality of these findings to the cigarette smoking of 5 human volunteers. During approximately 18 3-hr sessions, various combinations of response requirement (fixed-ratio 200, 400, and 1,600) and reinforcer magnitude (1, 2, and 4 puffs per bout) were arranged. Consumption (i.e., the number of puffs) generally was comparable at the same unit price independent of the response requirement and reinforcer magnitude comprising that unit price. In addition, increasing unit price generally decreased consumption in a positively decelerating fashion. These results extend the generality of the unit-price analysis to human cigarette smoking. Moreover, these results further support the position that reinforcer magnitude and response requirement are functionally equivalent and interact to determine consumption. The concept of unit price, by integrating and summarizing the effects of those two operations, provides a more parsimonious explanation of the results than do separate evaluations of the effects of response requirement and reinforcer magnitude.     

Books Received

Leg-to-body ratio (LBR) is one of the morphological traits that influences a person's attractiveness. To date, studies confirming that hypothesis have been conducted mainly in Western cultures. They have shown that the average or slightly higher-than-the-average LBR is perceived to be attractive in women. In the case of men, results were more ambiguous; however generally shorter or similar LBRs compared to females were attractive. Here, data on LBR preferences of a traditional, semi-nomad ethnic group (i.e., the Himba of northern Namibia, n = 81) are reported. Also in Himba people LBR influences a person's attractiveness. Similar to Western societies, extremely high and low LBRs were unattractive. However, contrary to previous findings, Himba preferred women of relatively low LBR and men of relatively high LBR.     

4～5岁儿童一一对应任务中的比例效应

一一对应和数量比较是幼儿数概念发展的两个重要方面。在本研究中．40名4岁和39名5岁的儿童分别完成了不同比例数量的一一对应任务和数量比较任务。结果表明：（1）两种实验任务下均出现比例效应．说明儿童在解决一一对应问题时,仍然用数量比较的方法来进行判断;（2）任务类型的主效应显著,一一对应任务下的正确率要显著低于数量比较任务下的正确率;（3）知觉线索更多地影响数量比较任务。