Effects of magnitude of food reinforcement on free-operant response rates

In Experiment 1 rats were trained to press a lever on a variable-ratio schedule of food presentation and were then exposed to progressively increasing magnitudes of food reinforcement. Response running rates (rates exclusive of the postreinforcement pause) were found to increase as a function of increasing reinforcement magnitudes. The effect of reinforcement magnitude on response rates inclusive of the postreinforcement pause, however, was less pronounced. Increases in the magnitude of reinforcement were also found to increase the length of the postreinforcement pause. Rats in Experiment 2 were trained to respond on a chained differential-reinforcement-of-low-rate variable-ratio schedule, and were exposed to increasing magnitudes of reinforcement as in Experiment 1. Response running rates increased in the variable-ratio component but decreased in the other component of the schedule. The results are discussed with reference to incentive accounts of reinforcement and the action of reinforcement on the response units generated by the operative contingencies.     

Escape from serial stimuli leading to food

If the functional relations governing the strength of a conditioned reinforcer correspond to those obtained with other Pavlovian procedures (e.g., Kaplan, 1984), the termination of stimuli appearing early in the interval between successive food deliveries should be reinforcing. During initial training we presented four key colors, followed by food, in a recurrent sequence to each of 6 pigeons. This established a baseline level of autoshaped pecking. In later sessions, we terminated each of these colors or only the first color for a brief period following each peck, replacing the original color with a standard substitute to avoid darkening the key. Pecking decreased in the presence of the last color in the sequence but increased in the presence of the first. In accord with contemporary models of Pavlovian conditioning, these and other data suggest that the behavioral effects of stimuli in a chain may be better understood in terms of what each stimulus predicts, as measured by relative time to the terminal reinforcer, than in the exclusively positive terms of the traditional formulation (Skinner, 1938). The same model may also account for the initial pause under fixed-interval and fixed-ratio schedules of reinforcement.     

时距认知与疼痛的双向关系及其思考

时距认知与疼痛的关系成为研究者重点关注的主题之一。为了帮助研究者更完整地理解这两种关系及其潜在机制以及更有效地干预疼痛和时距认知, 首先从双向关系的视角指出, 一方面, 疼痛导致时距认知出现延长、缩短或无影响三类结果; 另一方面, 时距认知会提高、降低或无影响疼痛的强度、忍耐力和敏感性。接着, 进一步在注意闸门理论、闸门控制理论以及神经矩阵理论等框架内解释上述结果。最后, 未来研究应重点关注几个科学问题:其一, 注意和唤醒在疼痛影响时距认知偏离方向的中介作用机制以及边界条件; 其二, 注意和唤醒在时间提示和持续时间对疼痛忍耐力或疼痛敏感性的中介作用机制以及边界条件; 其三, 疼痛干预和时间干预的操纵机制。     

The relationship of perfectionism with psychological symptoms in cancer patients and the contributing role of hyperarousability and coping

Objective: Significant levels of anxiety, depression and insomnia symptoms are found in cancer patients. Perfectionism, arousability and coping have been associated with these psychological symptoms in the general population but their role among cancer patients remains to be assessed. This study examined the longitudinal relationships between perfectionism and psychological symptoms (anxiety, depression, insomnia), and the intermediate role of the arousability trait and coping strategies.

Design: Participants (N = 853) completed the Multidimensional Perfectionism Scale, the Coping with Health Injuries and Problems questionnaire and the Arousal Predisposition Scale at the perioperative period (T1), and the Hospital Anxiety and Depression Scale and the Insomnia Severity Index two months later (T2).

Results: Higher levels of perfectionism (T1) were correlated with greater symptoms of anxiety, depression and insomnia (T2). Moderated mediation models indicated that arousability contributed to the association of perfectionism with all symptoms, with stronger associations found in men than in women. Coping was a significant pathway between perfectionism and anxiety, with associations of a comparable magnitude across sexes.

Conclusion: If these results are replicated by future longitudinal studies, they would suggest that perfectionist cancer patients are at a higher risk of experiencing psychological symptoms, partly through their hyperarousability and the coping strategies they use.