Delay discounting as impaired valuation: Delayed rewards in an animal obesity model

Obesity is a major public health problem, which, like many forms of addiction, is associated with an elevated tendency to choose smaller immediate rather than larger delayed rewards, a response pattern often referred to as excessive delay discounting. Although some accounts of delay discounting conceptualize this process as impulsivity (placing the emphasis on overvaluing the smaller immediate reward), others have conceptualized delay discounting as an executive function (placing the emphasis on delayed rewards failing to retain their value). The present experiments used a popular animal model of obesity that has been shown to discount delayed rewards at elevated rates (i.e., obese Zucker rats) to test two predictions that conceptualize delay discounting as executive function. In the first experiment, acquisition of lever pressing with delayed rewards was compared in obese versus lean Zucker rats. Contrary to predictions based on delay discounting as executive function, obese Zucker rats learned to press the lever more quickly than controls. In the second experiment, progressive ratio breakpoints (a measure of reward efficacy) with delayed rewards were compared in obese versus lean Zucker rats. Contrary to the notion that obese rats fail to value delayed rewards, the obese Zucker rats' breakpoints were (at least) as high as those of the lean Zucker rats.     

抑郁症的内表现型:快感缺失及其测量方法

快感缺失,指的是体验快乐的能力下降,广泛出现在抑郁症中,但同时也是其他如精神分裂症的重要症状。虽然快感缺失在精神病理学上非常重要,但较少受到研究重视。文章探讨了抑郁症和快感缺失的关系以及快感缺失个体的大脑奖励系统受损的神经机制,同时介绍了快感缺失可以进一步区分为期待性和消费性两种损害类型以及研究所用的主客观测量方法。指出快感缺失作为抑郁症最有可能的内表现型及其对疾病发展的作用,需要进一步研究深入。     

Strategic value-directed learning and memory in Alzheimer's disease and behavioural-variant frontotemporal dementia

In healthy adults, the ability to prioritize learning of highly valued information is supported by executive functions and enhances subsequent memory retrieval for this information. In Alzheimer's disease (AD) and behavioural-variant frontotemporal dementia (bvFTD), marked deficits are evident in learning and memory, presenting in the context of executive dysfunction. It is unclear whether these patients show a typical memory bias for higher valued stimuli. We administered a value-directed word-list learning task to AD (n = 10) and bvFTD (n = 21) patients and age-matched healthy controls (n = 22). Each word was assigned a low, medium or high point value, and participants were instructed to maximize the number of points earned across three learning trials. Participants’ memory for the words was assessed on a delayed recall trial, followed by a recognition test for the words and corresponding point values. Relative to controls, both patient groups showed poorer overall learning, delayed recall and recognition. Despite these impairments, patients with AD preferentially recalled high-value words on learning trials and showed significant value-directed enhancement of recognition memory for the words and points. Conversely, bvFTD patients did not prioritize recall of high-value words during learning trials, and this reduced selectivity was related to inhibitory dysfunction. Nonetheless, bvFTD patients showed value-directed enhancement of recognition memory for the point values, suggesting a mismatch between memory of high-value information and the ability to apply this in a motivationally salient context. Our findings demonstrate that value-directed enhancement of memory may persist to some degree in patients with dementia, despite pronounced deficits in learning and memory.     

药物成瘾者决策缺陷的特征、机制及干预

药物成瘾者存在决策缺陷, 并表现出冲动性、风险寻求、奖赏失调、躯体内感信号缺失等特征。神经影像学研究表明药物滥用导致成瘾者背外侧前额皮层、前扣带回、眶额叶皮层、腹内侧前额皮层、杏仁核、脑岛等脑区受损, 这些损伤是引发其决策缺陷的主要原因。认知训练有利于提高个体的决策能力, 如目标管理训练和正念冥想等可以增强个体工作记忆、促进自我觉察和以目标为导向的行为; 而非侵入性脑刺激则可以直接改变与成瘾者决策相关脑区的激活状态, 从而提升与决策相关的认知功能。总体而言, 未来认知训练和非侵入性脑刺激在成瘾干预方面仍有广阔的拓展空间。     

焦虑情绪对奖赏学习的影响

焦虑是在我们日常生活中占据重要地位的一种情绪, 对人类的决策行为能够产生显著影响。探讨决策研究的重要领域--奖赏学习, 可以帮助我们更深入地认识焦虑情绪在决策过程中扮演的角色。过往研究者较少关注焦虑对奖赏学习的潜在影响, 而且已有研究在实验技术和任务范式方面存在一定的局限性。考虑到奖赏学习概念的复杂性, 为了全面地考察个体焦虑水平与奖赏学习的关系, 本文作者建议设置不同类型的奖赏学习情境, 例如概率学习、联结学习、逆向学习和社会学习等。在上述各类不同任务中, 个体焦虑水平对奖赏学习能力的影响模式可能并不一致, 有待研究者们进行深入探讨。     

Cooperative Learning Groups at the College Level: Differential Effects on High, Average, and Low Exam Performers

A repeated-measures mixed-design was used in examining the effects of cooperative learning study teams on exam performance for 378 undergraduate students enrolled in one of 10 large sections of an introductory educational psychology course over a two-semester period. Students were assigned to 5-member cooperative groups based on previous exam achievement (low, average, high). Bonuses (20% of exam score) were offered to groups who improved their mean exam performance to a pre-established criterion in the cooperative-group phase. Results yielded an overall effect size of 0.42 for cooperative study versus individual study. Students who had obtained low and average scores on the preceding exam improved significantly during cooperative study, but the previously high achievers decreased somewhat.     

Fluent Reading as the Improvement of Stimulus Control: Additive Effects of Performance-Based Interventions to Repeated Reading on Students' Reading and Error Rates

The impact of adding performance-based interventions to a skill-based intervention on oral reading fluency was examined with 3 elementary students identified as having difficulty with reading. Two performance-based interventions were combined with the skill-based intervention Repeated Reading (RR) to create the three instructional packages investigated. The packages included Repeated Readings (RR), Repeated Readings with Performance Feedback (RR/FB), and Repeated Readings with Performance Feedback and Contingent Reward (RR/FB/REW). Results suggested that Repeated Reading (RR) alone led to the greatest increase in reading fluency for participants with the highest reading rates and lowest error rates at baseline. In contrast, the participant who exhibited the lowest reading rate and highest error rate benefited the most when Repeated Readings was offered in conjunction with Performance Feedback (RR/FB) or Performance Feedback plus Contingent Reward (RR/FB/RW). Implications for blending skill- and performance-based interventions to develop stimulus control over fluent reading and future research directions are discussed.     

Immediate reinforcement in delayed reward learning in pigeons

Pigeons were trained on simultaneous red-green discrimination procedures with delayed reward and sequences of stimuli during the delay. In Experiment 1, three stimuli appeared during the 60-second intervals between the correct responses and reward, and the incorrect responses and nonreward. The stimulus that immediately followed a correct response also preceded nonreward, and the stimulus that followed an incorrect response preceded reward. These stimuli were 10 or .33 second in duration for different groups. Stimuli during the remainder of the delay interval differed following correct and incorrect responses. Group 10 initially persisted in the nonrewarded choice, but shifted to a preponderance of rewarded responses after further training. Group .33 rapidly acquired the correct response. Similar results were obtained in Experiment 2 where delay intervals consisted of opposite sequences of two stimuli of equal duration and total delays were 6, 20, or 60 seconds. Early in training, generalization of differential conditioned-reinforcing properties from the conditions preceding reward and nonreward to postchoice conditions had a greater effect relative to backchaining than it did later. It was concluded that delayed-reward learning is best analyzed in terms of the conditioned-reinforcing value of the patterns of cues that follow immediately after rewarded and nonrewarded responses.     

After the puzzle boxes: thorndike in the 20th century

From the beginning of this century, following the publication of his dissertation, Thorndike made many significant contributions to psychology, some related to animal and human learning and others to various areas of educational psychology. This paper concentrates on the former and mentions some of the latter, in the context of personal and professional aspects of his life.     

Reward Density And Variable-interval Schedule Performance In An Open Economy

There is no general agreement regarding the form of the relation between response rate and reinforcement rate when single schedules of reinforcement are studied in an open economy. The present study assessed the form of this relation using reward density, which incorporates both reinforcement rate and duration of access to food, as an independent variable. Reward density was manipulated with 4 pigeons by changing the value of the variable-interval schedule, the hopper duration, or both. The relations between response rate and reward density were sharply rising and hyperbolic in 3 of 4 pigeons, replicating results obtained by Catania and Reynolds (1968). Because eating efficiency was lower in conditions that provided longer hopper durations, programmed reward densities differed from obtained reward densities. When response rates were examined as a function of obtained reward densities, the same relations were demonstrated more strongly. In further clarifying the relation between response rate and reward density in an open economy, these results lend support to the conclusion that open and closed economies yield different behavioral effects.