Human operant performance: Sensitivity and pseudosensitivity to contingencies

Undergraduates' button presses occasionally produced points exchangeable for money. Left and right buttons were initially correlated with multiple random-ratio (RR) and random-interval (RI) components, respectively. During interruptions of the multiple schedule, students filled out sentence-completion guess sheets describing the schedules, and points were contingent upon the accuracy of guesses. To test for sensitivity to schedule contingencies, schedule components were repeatedly reversed between the two buttons. Pressing rates were consistently higher in ratio than in interval components even when feedback for guesses was discontinued, demonstrating sensitivity to the difference between ratio and interval contingencies. The question was whether this sensitivity was based directly on the contingencies or whether it was rule-governed. For two students, when multiple RR RI schedules were changed to multiple RI RI schedules, rates became low in both components of the multiple RI RI schedule; however, subsequent prevention of point deliveries for the first few responses in any component produced high rates in that component. For a third student, response rates became higher in the RI component that provided the lower rate of reinforcement. In each case, performance was inconsistent with typical effects of the respective schedules with nonhuman organisms; it was therefore plausible to conclude that the apparently contingency-governed performances were instead rule-governed.     

Effects of self-generated rules on the development of schedule-controlled behavior.

College students responded under a multiple differential-reinforcement-of-low-rate 5-s fixed-ratio 8 schedule, with components alternating every 2 min. After 40 programmed minutes of acquisition and 12 min of maintenance, without notice, both schedules changed to extinction for 28 min. During acquisition, between alternations of the multiple schedule, some subjects were asked to develop rules describing the schedule contingencies. Other subjects were given these same rules between alternations, and a third group neither received nor were asked to develop rules. By the end of the acquisition phase, self-generated-rule subjects were more likely to show schedule-typical behavior than were subjects not asked to generate rules. The behavior of those given rules was similar to those asked to generate rules at the end of acquisition, but yoked-rule subjects acquired schedule-typical behavior at a quicker rate. By the end of extinction, during the period corresponding to the previous fixed-ratio interval, all no-rule subjects who had earned points during acquisition and maintenance were responding at a rate of less than 30 responses per minute. Only 3 of the 9 self-generated-rule subjects and 2 of the 5 yoked-rule subjects were similarly responding at this low rate. Results suggest that asking subjects to develop self-rules facilitates acquisition, but can retard extinction. Results also suggest that self-generated rules function similarly to external rules.     

Sensitivity to aversive events in depression: Antecedent,concomitant, or consequent?

This study tested whether sensitivity to aversive events is a concomitant versus antecedent/consequent of depression. Twenty currently depressed subjects, twenty subjects with remitted depression, and twenty control subjects completed psychophysiological and learning tasks involving aversive components. Both currently depressed and remitted subjects, when compared to control subjects, exhibited greater decreases in skin resistance response reactions to negative social scenes and a greater sensitivity to extinction in the learning condition involving an aversive component. The fact that the responses of remitted subjects were very similar to those of currently depressed subjects on both tasks is consistent with the view that sensitivity to aversive events is an antecedent or consequent of depression, as opposed to being only a concomitant. The results also provide some support for the passive avoidance model of depression.This study was based on portions of a doctoral dissertation by the first author, with the second author as chairperson, at the University of North Carolina at Greensboro.This research was aided by a Grant-in-Aid of Research to the first author from Sigma Xi, The Scientific Research Society, an award from the Jill Shelby Memorial Fund to the first author, and support from National Institute of Mental Health Grant MH17071, awarded to C. R. Snyder.Portions of this paper were presented at the meeting of the American Psychological Association, New Orleans, August 1989, and at the meeting of the Association for the Advancement of Behavior Therapy, Washington, DC, November, 1989.     

Coping and sensitivity to aversive events

To test further the sensitivity to aversive events hypothesis, males and females varying in level of depressed mood listened to positive, negative, and neutral social scenes while psychophysiological measurements were obtained. In addition, the relations among response styles, coping strategies, and psychological adjustment were examined. Results indicated that only dysphoric females responded in ways consistent with the sensitivity hypothesis, exhibiting greater electrodermal responses to negative social scenes compared to nondysphoric females. No differences in psychophysiological sensitivity were found between dysphoric and nondysphoric males. Dysphoric students engaged in more ruminative type responses in reaction to their depressed mood and reported using more avoidant coping strategies in response to stress. In particular, females utilized more ruminative strategies in response to a depressed mood and more emotion-focused coping strategies in response to stressful events in general. The implications for these results are discussed within a diathesis-stress framework.     

Sensitivity to reinforcer duration in a self-control procedure

In a concurrent-chains procedure, pigeons' responses on left and right keys were followed by reinforcers of different durations at different delays following the choice responses. Three pairs of reinforcer delays were arranged in each session, and reinforcer durations were varied over conditions. In Experiment 1 reinforcer delays were unequal, and in Experiment 2 reinforcer delays were equal. In Experiment 1 preference reversal was demonstrated in that an immediate short reinforcer was chosen more frequently than a longer reinforcer delayed 6 s from the choice, whereas the longer reinforcer was chosen more frequently when delays to both reinforcers were lengthened. In both experiments, choice responding was more sensitive to variations in reinforcer duration at overall longer reinforcer delays than at overall shorter reinforcer delays, independently of whether fixed-interval or variable-interval schedules were arranged in the choice phase. We concluded that preference reversal results from a change in sensitivity of choice responding to ratios of reinforcer duration as the delays to both reinforcers are lengthened.     

儿童拒绝敏感性与自我知觉的关系:一项交叉滞后研究

采用儿童拒绝敏感性问卷与儿童自我知觉量表对596名中小学儿童进行了为期一年的追踪调查,通过交叉滞后回归分析考察儿童拒绝敏感性与多种自我知觉间的预测关系。结果发现：（1）自我知觉的年级差异显著,初中儿童的自我知觉水平较低;（2）在两次测量中,拒绝敏感性与多种自我知觉均呈显著的负相关;（3）控制性别、年级以及自身稳定性之后,第一年的多种自我知觉均可以负向预测第二年的拒绝敏感性,而第一年的拒绝敏感性仅可以负向预测第二年的体貌及一般自我知觉;（4）年级调节了拒绝敏感性与一般和行为自我知觉间的纵向关系,并在小学与初中儿童中表现出不同的模式。研究证实自我知觉是儿童拒绝敏感性形成的重要原因之一,为儿童社会认知及心理健康的相关研究提供新的实证依据。     

Rat choice in rapidly changing concurrent schedules

In two experiments, experimentally naïve rats were trained in concurrent variable‐interval schedules in which the reinforcer ratios changed daily according to a pseudorandom binary sequence. In Experiment 1, relative response rates showed clear sensitivity to current‐session reinforcer ratios, but not to previous sessions' reinforcer ratios. Within sessions, sensitivity to the current session's reinforcement rates increased steadily, and by session end, response ratios approached matching to the current‐session reinforcer ratios. Across sessions, sensitivity to the current session's reinforcer ratio decreased with continued exposure to the pseudorandom binary sequence, contrary to expectations based on previous studies demonstrating learning sets. Using a second group of naïve rats, Experiment 2 replicated the main results from Experiment 1 and showed that although there were increases over sessions in both changeover rate and response rate during the changeover delay, neither could explain the accompanying reductions in sensitivity. We consider the role of reinforcement history, showing that our results can be simulated using two separate representations, one local and one nonlocal, but a more complex approach will be needed to bring together these results and other history effects such as learning sets and spontaneous recovery.     

Loneliness,HPA stress reactivity and social threat sensitivity: Analyzing naturalistic social challenges

Loneliness has been linked to poor health through an increased activation of threat surveillance mechanisms, such as the hypothalamic‐pituitary‐adrenal axis (HPA ). The socio‐cognitive model (Cacioppo & Hawley) proposes that lonely people have an increased social threat sensitivity which activates the HPA axis. The current study examined the impact of loneliness on HPA stress reactivity and social threat sensitivity in response to naturally occurring social challenges. Participants (N = 45) were prospective undergraduates attending a 3‐day university preparation programme over the summer, prior to commencing their university studies. Cortisol levels and perceived stress were measured before and after an ice breaker session on Day 1 and a lecture session on Day 3. Social threat sensitivity was also measured on the first and third day. When meeting unfamiliar peers in the ice breaker session, HPA stress reactivity was evident, but it was not markedly different in those who reported high levels of loneliness than those with low levels. The high loneliness group had higher levels of perceived stress and increased social threat sensitivity than the low loneliness group on both testing days. The findings show partial support for the socio‐cognitive model of loneliness because increased threat sensitivity was demonstrated in the high loneliness group. The findings indicate that lonely people do not respond in a physiologically different way to specific social challenges, but they typically report higher social threat sensitivity and higher perceived stress than their non‐lonely peers.     

MEDIATING ROLE OF MATERNAL SENSITIVITY: ENHANCING LANGUAGE DEVELOPMENT IN AT‐RISK FAMILIES

Home‐visiting programs have gained increasing importance in family‐centered prevention and intervention. However, few studies have examined the mechanisms underlying early intervention treatment effects. The goal of this study is to analyze the mediating role of maternal sensitivity in enhancing language development with the home‐visiting program Parents as Teachers (PAT). Data were collected and analyzed within the ongoing, long‐term ZEPPELIN study, a randomized controlled trial with 251 participating at‐risk families. Via longitudinal mediation analysis, we examined whether effects of the PAT on receptive and expressive language outcomes at 24 and 36 months were mediated by maternal sensitivity at 12 months. Within a moderated mediation framework, we investigated whether the level of family psychosocial stress affects this mediation. Results showed that intervention effects on language outcomes are mediated by maternal sensitivity—weakly and through specific pathways. Moderation and moderated mediation analyses indicated that effects of the PAT and also specific mediation effects increase with the level of psychosocial stress. Implications of the results for practice are discussed.