On the discriminability of stimulus duration.

The performance of pigeons trained to detect differences in the duration of stimuli was analysed using a matching model of signal detection. Two white stimuli, S1 and S2, differing in duration, were arranged with equal probability on the center key of a three-key chamber. S1 was systematically varied from 5 seconds to 25 seconds while S2 remained constant at 30 seconds. On completion of the center-key stimulus, a peck on the center key turned on the two red side keys. A left-key response was "correct" when S1 had been in effect on the center key and a right-key response was "correct" on S2 trials. A correct response produced a 3-second magazine light accompanied intermittently by food. Incorrect responses produced 3-second blackouts. Detection performance was measured under two procedures. In the first, the obtained reinforcement ratio was uncontrolled by allowing the number of food reinforcements obtained for correct left- and right-key responses to vary as the stimuli were changed. In the second procedure, the presentation of food reinforcement was controlled by holding the obtained reinforcement ratio constant. Discriminability changed as a function of stimulus differences under both procedures. No such trend was found in response bias.     

Contrast and undermatching as a function of reinforcer duration and quality during multiple schedules

Eight pigeons pecked keys under multiple variable-interval two-minute variable-interval two-minute schedules. In Experiment 1, the reinforcers were 2, 4, or 8 seconds access to a food magazine. In Experiments 2 and 3, the reinforcers were grains that had been determined to be most-, moderately-, or non-preferred. Both positive and negative behavioral contrast occurred when the reinforcers in one component were held constant and the duration or type of reinforcer obtained in the other component varied. Undermatching occurred when the relative rate of responding during a component was plotted as a function of the relative duration of the reinforcers in that component.     

The following schedule of reinforcement as a fundamental determinant of steady state contrast in multiple schedules

Two experiments investigated whether steady-state interactions in multiple schedules depend exclusively on the following schedule of reinforcement. Experiment 1 used a four-component multiple schedule in which two components were associated with the same constant schedule of reinforcement, and where rate of reinforcement was varied in the component that followed one of these. Contrast effects were reliable only in the component that preceded the point of reinforcement variation, although some contrast did occur otherwise. In those instances where contrast other than the following-schedule effect did occur, it was accounted for by the effect of the preceding schedule, an effect for which there were consistent individual differences among subjects, and which varied with component duration. Experiment 2 used a three-component schedule, in which reinforcement rate was varied in the middle component. The results were consistent with Experiment 1, as the following-schedule effect was the only consistent effect that occurred, although an effect of the preceding schedule did occur for some subjects under some conditions, and was especially evident early in training. The conclusion from both experiments is that there is no general effect of relative rate of reinforcement apart from the sum of the effects of the preceding and following schedules, and that the following-schedule effect is the fundamental cause of steady-state interactions.     

Two types of pigeon key pecking: suppression of long- but not short-duration key pecks by duration-dependent shock

The key pecking of eight pigeons was maintained on a variable-interval 1-minute schedule of food reinforcement. Sometimes, all responses between 35 and 50 milliseconds in duration produced a shock; sometimes, all responses between 10 and 25 milliseconds produced a shock; sometimes, shocks were produced by pecks without regard to duration (nondifferential punishment), and sometimes shocks were delivered independently of responding. Punishment of 35- to 50-millisecond responses selectively suppressed those responses, while punishment of 10- to 25-millisecond responses and nondifferential punishment suppressed responding overall but did not suppress responses of particular duration. Punishment of 35- to 50-millisecond responses suppressed key pecking slightly less than did nondifferential punishment. Punishment of 10- to 25-millisecond responses and response-independent shock produced roughly equal amounts of suppression, substantially less than the other punishment procedures. The data support the view that there are at least two kinds of key peck, identifiable on the basis of duration, one of which (short duration) is insensitive to its consequences.     

Dimensional stimulus control following brief wavelength training

Pigeons with extensive training pecking a key illuminated by a white line then had brief training with the key illuminated by 555 nanometers. This was immediately followed by a wavelength generalization test in extinction. Dimensional stimulus control about the training wavelength increased with the duration and number of reinforcements given on variable-interval 30-sec and variable-interval 10-sec schedules in Experiment I. In Experiment II, dimensional stimulus control was obtained after only 4 min of wavelength training from birds with prior and independent discrimination training. Experiment III provided groups equated in number of reinforcers with groups in Experiment I and two 8-min duration groups. Analyses, which included results from both Experiments I and III, showed that dimensional stimulus control increased: (a) more rapidly as a function of the duration of variable-interval 10-sec than variable-interval 30-sec reinforcement; (b) at the same rate across variable-interval reinforcement schedules, as a function of the number of reinforcers available during brief wavelength training.     

受欺负与青少年外化问题关系的“健康环境悖论”：敌意性归因的中介作用

“健康环境悖论”是指在总体受欺负水平较低的环境中, 受欺负的个体会表现出更多适应问题。本研究以来自47个班级的1764名5年级到8年级学生为被试(男生956人, 平均年龄14.46岁), 考察了班级平均受欺负水平在个体受欺负经历与外化问题间的调节作用及敌意性归因的中介作用。结果发现：(1)受欺负与外化问题的关系存在“健康环境悖论”现象, 即班级平均受欺负水平能调节个体受欺负经历与外化问题的关系, 在班级平均受欺负水平较低的班级中受欺负经历与外化问题的关联更强; (2)班级平均受欺负水平对受欺负与外化问题的调节作用通过敌意性归因的中介作用实现。本研究证实了受欺负与外化问题的健康环境悖论现象, 并首次揭示了敌意性归因的中介作用机制。     

班级环境如何影响受欺负者的适应？健康环境悖论及其发生机制

“健康环境悖论”是指在受欺负水平相对较低的环境中,受欺负个体有更多的适应问题。通过梳理相关实证研究,本文从人际与认知两大方面分析健康环境悖论的发生机制。人际机制强调健康环境会影响同伴群体对于受欺负者的态度和受欺负者的友谊,这些不良的人际关系进一步加剧受欺负者的适应困难。认知机制认为健康环境会通过向上的社会比较和消极归因方式,影响受欺负者的适应问题。最后,我们讨论了中国文化背景下“健康环境悖论”的适用性问题、未来研究的发展方向和对于干预实践的建议。     

新时代青少年羞怯对同伴侵害的影响：依存型和独立型自我建构的作用

本研究的主要目的是考察羞怯对同伴侵害的影响及潜在机制。1036名青少年(52%是男孩; M = 12.97 岁, SD = .76)完成了自评问卷。结果发现：(1)羞怯显著地正向预测青少年的同伴侵害;(2)自我建构调节了这一关系,依存型自我建构对羞怯个体的同伴问题具有保护作用,而独立型自我建构具有破坏作用;(3)性别对这一关系的调节作用并不显著。这些发现强调了在羞怯的适应功能研究中考虑文化的个人层面因素的重要性。     

Bullying as a group process: Participant roles and their relations to social status within the group

Bullying was investigated as a group process, a social phenomenon taking place in a school setting among 573 Finnish sixth-grade children (286 girls, 287 boys) aged 12–13 years. Different Participant Roles taken by individual children in the bullying process were examined and related to a) self-estimated behavior in bullying situations, b) social acceptance and social rejection, and c) belongingness to one of the five sociometric status groups (popular, rejected, neglected, controversial, and average). The Participant Roles assigned to the subject were Victim, Bully, Reinforcer of the bully, Assistant of the bully, Defender of the victim, and Outsider. There were significant sex differences in the distribution of Participant Roles. Boys were more frequently in the roles of Bully, Reinforcer and Assistant, while the most frequent roles of the girls were those of Defender and Outsider. The subjects were moderately well aware of their Participant Roles, although they underestimated their participation in active bullying behavior and emphasized that they acted as Defenders and Outsiders. The sociometric status of the children was found to be connected to their Participant Roles. © 1996 Wiley-Liss, Inc.