Matching under nonindependent variable-ratio schedules of drug reinforcement.

Response-contingent deliveries of oral pentobarbital maintained responding of 3 rhesus monkeys during daily 3-hr sessions. Deliveries of pentobarbital were arranged under nonindependent concurrent variable-ratio variable-ratio schedules. Responses to either schedule counted toward completion of both variable-ratio schedule requirements. This schedule is similar in some respects to conventional concurrent variable-interval variable-interval schedules, in which passage of time counts toward completion of the interval value on both schedules. Restricted nonindependent concurrent variable-ratio variable-ratio schedules were also studied. On that schedule, when a drug delivery was assigned to one spout, it had to be collected before responses on the opposite spout again counted toward completion of the schedule requirements. Relative reinforcer magnitude was varied by changing the drug concentration on one schedule while keeping the drug concentration constant on the other variable-ratio schedule. Under both types of concurrent variable-ratio schedules, the relative rate of responding corresponded to the relative drug intake. Unlike earlier studies of concurrent variable-interval variable-interval intravenous cocaine reinforcement, preference was proportionate to concentration, and exclusive preferences did not develop. The relationship between relative rate of responding and relative drug intake was well described by the generalized matching law.     

一般社会情境中风险认知的实验研究

风险认知是一个新的研究领域,随着经济的发展应愈来愈受到重视。本研究在一般社会情境下,讨论了对46个风险因素的风险程度及风险特征的知觉;个性特征与风险认知的关系;群体的风险认知类型特征,以及各样本间的比较分析。研究结论提供了公众风险认知结构的初步轮廓。     

Effects of social context, reinforcer probability, and reinforcer magnitude on humans' choices to compete or not to compete.

In the first two experiments, subjects' choices to earn points (exchangeable for money) either by competing with a fictitious opponent or by not competing were studied. Buskist, Barry, Morgan, and Rossi's (1984) competitive fixed-interval schedule was modified to include a second response option, a noncompetitive fixed-interval schedule. After choosing to enter either option, the opportunity for reinforcers became available after the fixed-interval's duration had elapsed. Under the no-competition condition, points were always available after the interval had elapsed. Under the competition condition, points were available based on a predetermined probability of delivery. Experiments 1 and 2 examined how reinforcer probabilities and reinforcer magnitudes affected subjects' choices to compete. Several general conclusions can be made about the results: (a) Strong preferences to compete were observed at high and moderate reinforcer probabilities; (b) competing was observed even at very low reinforcer probabilities; (c) response rates were always higher in the competition component than in the no-competition component; and (d) response rates and choices to compete were insensitive to reinforcer-magnitude manipulations. In Experiment 3, the social context of this choice schedule was removed to determine whether the high levels of competing observed in the first two experiments were due to a response preference engendered by the social context provided by the experimenters through instructions. In contrast to the first two experiments, these subjects preferred the 60-s fixed-interval schedule (formerly the no-competition option), indicating that the instructions themselves were responsible for the preference to compete. This choice paradigm may be useful to future researchers interested in the effects of other independent variables (e.g., drugs, social context, instructions) on competitive behavior.     

Synergistic effects of ethanol and cocaine on brain stimulation reward.

The effects of two widely abused drugs, ethanol and cocaine, were examined alone and in combination on intracranial reward processes. In agreement with previous research, higher doses of both cocaine and ethanol alone produced facilitation of behavior maintained by brain stimulation reward. Low intraperitoneal doses of ethanol and cocaine, which alone did not affect performance, were found to reduce stimulation reward threshold and modestly increase response rate. The enhancement of brain stimulation reward by the combination of ethanol and cocaine suggests that both drugs may produce their rewarding effects through common neuronal substrates and that they may potentiate the abuse of each other.     

Reward dominance among children with disruptive behavior disorders

Investigated was a deficit in avoidance learning in situations of competing rewards and punishments in boys with behavior disorders. This learning style has been found to differentiate adults with psychopathy and controls and has been labeled reward dominance. The present study investigated the reward dominance paradigm in a group of 9- to 13-year-old boys with disruptive behavior disorders (N=21) and a normal control group (N=22). Subjects played four computer games programmed to provide the subject with a steadily decreasing ratio of rewards to punishments. Although the groups did not differ initially on the number of trials played, significant group differences emerged when measures of anxiety were included in the analysis. That is, boys with disruptive behavior disorders played more trials (reward dominance) only when the effect of anxiety was controlled. These findings are consistent with Gray's biobehavioral theory of personality and are also consistent with research indicating that anxiety is an important marker for a distinct subgroup of children with behavior problems.     

Confirmation of linear system theory prediction: Changes in Herrnstein's k as a function of changes in reinforcer magnitude

Eight human subjects pressed a lever on a range of variable-interval schedules for 0.25¢ to 35.0¢ per reinforcement. Herrnstein's hyperbola described seven of the eight subjects' response-rate data well. For all subjects, the y-asymptote of the hyperbola increased with increasing reinforcer magnitude and its reciprocal was a linear function of the reciprocal of reinforcer magnitude. These results confirm predictions made by linear system theory; they contradict formal properties of Herrnstein's account and of six other mathematical accounts of single-alternative responding.     

Sensitive caregiving and reward responsivity: A novel mechanism linking parenting and executive functions development in early childhood

Sensitive caregiving is an essential aspect of positive parenting that influences executive functions development, but the mechanisms underlying this association are less clear. Using data from the Family Life Project, a large prospective longitudinal sample of 1292 families residing in rural, predominately low-income communities, the current study examined whether sensitive caregiving impacts executive functions development by shaping behavioral reward processing systems in early postnatal life. Results indicated that higher levels of sensitive caregiving during infancy were associated with heightened reward responsivity at age 4, which in turn predicted superior executive functions ability at age 5. Notably, children's reward responsivity partially mediated the relationship between sensitive caregiving in infancy and executive functions ability at school entry. These findings add to prior work on early experience and children's executive functions and highlight caregiver scaffolding of developing reward processing systems as a potential foundational mechanism for supporting adaptive behavior and self-regulation across the lifespan.     

Blunted reward responsiveness prospectively predicts emotional distress when exposed to a naturalistic stressor

Both stress and blunted reward responsiveness have been identified as core risk factors of depression. Whether blunted reward responsiveness increases psychological vulnerability to real-life stress from a dynamic perspective (from stress reactivity to recovery) has not been investigated. By utilizing a real-world stressful event (i.e. the final examination), this study aimed to explore the role of reward responsiveness in the stress-emotional distress relationship during stress reactivity and recovery phases. We followed 57 undergraduates with three assessments, from six weeks before examination weeks (T1, baseline), one day before the examinations (T2) to two weeks after the examinations (T3), therefore, covering stress reactivity (T1 to T2) and recovery (T2 to T3) phases. At baseline, reward responsiveness was measured as the Reward Positivity (RewP) in the doors task. Stress and emotional distress (anxiety and depression) were reported at T1, T2 and T3 to capture their dynamic changes. Results showed that self-report stress levels significantly increased from T1 to T2 (stress reactivity phase) and decreased from T2 to T3 (stress recovery phase). Furthermore, blunted reward responsiveness at baseline prospectively predicted emotional distress during the stress reactivity phase but not the recovery phase. Specifically, during the stress reactivity phase, higher perceived stress was associated with greater anxiety and depression only in participants with relatively smaller residual RewP amplitudes but not in participants with relatively larger residual RewP amplitudes. Our study demonstrated that a blunted reward responsiveness is a vulnerable factor of depression, especially when exposed to stress. Our findings provide insights into prevention and intervention for stress-related disturbance.     

奖赏结构与结果效价对儿童自我—他人成就归因与评价的影响

本研究旨在考察不同的奖赏结构和结果效价对儿童自我-他人成就归因、自我-他人奖赏评价的影响。实验采用2×2×2混合设计,其中自我-他人归因与评价为被试内设计。被试为小学五年级学生74名(男生36人,女生38人),实验通过解决一系列迷津测验来创设成功和失败情境。实验结果表明,奖赏结构对儿童自我-他人能力归因的影响、奖赏结构与自我-他人归因的交互作用对能力归因的影响、自我-他人运气归因均达到了显著性水平;努力和任务难度归因不显著;儿童对自我和他人的成就结果倾向于做能力和运气归因,较为忽略努力和任务难度在成就行为中的作用。     

Religiopoiesis

Religiopoiesis describes the crafting of religion, a core activity of humankind. Each religion is grounded in its myth, and each myth includes a cosmology of origins and destiny. The scientific worldview coheres as such a myth and calls for a religiopoietic response. The difficulties, opportunities, and imperatives inherent in this call are explored, particularly as they impact the working scientist.