时间贴现的性质与脑机制

时间贴现是指个人对事件的价值量估计随着时间的流逝而下降的心理现象,它是行为选择理论的一个重要组成部分。着重介绍了时间贴现的数学模型（指数模型、双曲线模型族、非双曲线模型）、时间贴现现象和概率贴现现象的联系、延迟兑现与提前兑现时间贴现不对称现象及其理论解释,还讨论了时间贴现现象的神经机制研究。提出了时间贴现未来研究的几个主要问题     

假言推理中的概率效应

近来Oaksford等人的研究表明,概率信息对假言推理的认知过程有着显著的影响,在一定程度上可以用它来解释和预测个体在推理中的行为反应。该文针对这种新的观点,就假言推理中所涉及的前后件概率信息、条件概率信息、连接概率信息、因果概率信息以及额外前提条件等对假言推理的影响分别做了简要的阐述,并介绍了一些相关的实验研究,最后作了总结和展望。     

Preferred Difficulty and Subjective Probability in Different Action Phases

Drawing on Gollwitzer's deliberative–implemental mindset distinction (P. M. Gollwitzer, 1990), it was predicted that people who are deliberating on different actions or goals would be more cautious or more realistic in their expectation of success in subsequent tasks than people who are going to implement a chosen action or goal. Participants were given a choice between different test-materials. They were interrupted before (deliberative) or immediately after decision-making (implemental). They then either had to choose between various levels of difficulty within one type of task (Experiment 1) or they had to predict their own future performance (Experiment 2). The results showed that deliberative participants preferred less difficult tasks and overestimated their probability of success less than implemental participants. In addition, deliberative participants referred more than implemental participants to their past performance when selecting levels of difficulty or predicting future performance; however, the two groups did not differ in actual performance. Taken together, the findings suggest that people are more realistic in a deliberative than in an implemental state of mind. The present studies extend prior research because for the first time they document mindset effects on peoples' estimates concerning their future performance in the achievement domain.     

Choice and foraging: the effects of accessibility on acceptability.

Pigeons responded in a successive-encounters choice procedure in which accessibility of the less profitable of two outcomes varied either in terms of probability of encounter or search time to encounter (keeping search time to the more profitable outcome constant). When the less profitable outcome was made more probable its acceptance became more likely. However, when search time to encounter the less profitable outcome was shortened, its acceptance became less likely. Both results are consistent with the delay-reduction hypothesis and with an optimality model developed for application to the successive-encounters choice procedure.     

Comparing item characteristic curves

Test items are often evaluated and compared by contrasting the shapes of their item characteristics curves (ICC's) or surfaces. The current paper develops and applies three general (i.e., nonparametric) comparisons of the shapes of two item characteristic surfaces: (i) proportional latent odds, (ii) uniform relative difficulty, and (iii) item sensitivity. Two items may be compared in these ways while making no assumption about the shapes of item characteristic surfaces for other items, and no assumption about the dimensionality of the latent variable. Also studied is a method for comparing the relative shapes of two item characteristic curves in two examinee populations.The author is grateful to Paul Holland, Robert Mislevy, Tue Tjur, Rebecca Zwick, the editor and reviewers for valuable comments on the subject of this paper, to Mari A. Pearlman for advice on the pairing of items in the examples, and to Dorothy Thayer for assistance with computing.     

The role of contingencies and "principles of behavioral variation" in pigeons' pecking

Staddon and Simmelhag's proposal that behavior is produced by “principles of behavioral variation” instead of contingencies of reinforcement was tested in two experiments. In the first experiment pigeons were exposed to either a fixed-interval schedule of response-contingent reinforcement, an autoshaping schedule of stimulus-contingent reinforcement, or a fixed-time schedule of noncontingent reinforcement. Pigeons exposed to contingent reinforcement came to peck more rapidly than those exposed to noncontingent reinforcement. Staddon and Simmelhag's “principles of behavioral variation” included the proposal that patterns (interim and terminal) were a function of momentary probability of reinforcement. In the second experiment pigeons were exposed to either a fixed-time or a random-time schedule of noncontingent reinforcement. Pecking showed a constant frequency of occurrence over postfood time on the random-time schedule. Most behavior showed patterns on the fixed-time schedule that differed in overall shape (i.e., interim versus terminal) from those shown on the random-time schedule. It was concluded that both the momentary probability of reinforcement and postfood time can affect patterning.     

基于语料库统计的“音-形”激活概率及加工机制

为了了解心理词典中语音与汉字的联结情况以及从音到形的加工机制,研究首先计算出了基于语料库统计的“音-形”激活概率(某个音节激活其对应汉字的概率),并通过一个听写实验来验证这种激活概率是否反映实际加工中的激活情况。结果证明基于语料统计得到的“音-形”激活概率基本可以预测实际的“音-形”激活情况,表现为:“音-形”激活概率越高的汉字被激活的概率和强度越高,并且有明显的优势字效应; 该统计概率具有可独立于其他影响因素的预测功能。     

Prime and probability: causal knowledge affects inferential and predictive effects on self-agency experiences

Experiences of having caused a certain outcome may arise from motor predictions based on action–outcome probabilities and causal inferences based on pre-activated outcome representations. However, when and how both indicators combine to affect such self-agency experiences is still unclear. Based on previous research on prediction and inference effects on self-agency, we propose that their (combined) contribution crucially depends on whether people have knowledge about the causal relation between actions and outcomes that is relevant to subsequent self-agency experiences. Therefore, we manipulated causal knowledge that was either relevant or irrelevant by varying the probability of co-occurrence (50% or 80%) of specific actions and outcomes. Afterwards, we measured self-agency experiences in an action–outcome task where outcomes were primed or not. Results showed that motor prediction only affected self-agency when relevant actions and outcomes were learned to be causally related. Interestingly, however, inference effects also occurred when no relevant causal knowledge was acquired.     

Effects of reinforcer probability, delay, and response requirements on the choices of rats and pigeons: possible species differences

In Experiment 1 with rats, a left lever press led to a 5-s delay and then a possible reinforcer. A right lever press led to an adjusting delay and then a certain reinforcer. This delay was adjusted over trials to estimate an indifference point, or a delay at which the two alternatives were chosen about equally often. Indifference points increased as the probability of reinforcement for the left lever decreased. In some conditions with a 20% chance of food, a light above the left lever was lit during the 5-s delay on all trials, but in other conditions, the light was only lit on those trials that ended with food. Unlike previous results with pigeons, the presence or absence of the delay light on no-food trials had no effect on the rats' indifference points. In other conditions, the rats showed less preference for the 20% alternative when the time between trials was longer. In Experiment 2 with rats, fixed-interval schedules were used instead of simple delays, and the presence or absence of the fixed-interval requirement on no-food trials had no effect on the indifference points. In Experiment 3 with rats and Experiment 4 with pigeons, the animals chose between a fixed-ratio 8 schedule that led to food on 33% of the trials and an adjusting-ratio schedule with food on 100% of the trials. Surprisingly, the rats showed less preference for the 33% alternative in conditions in which the ratio requirement was omitted on no-food trials. For the pigeons, the presence or absence of the ratio requirement on no-food trials had little effect. The results suggest that there may be differences between rats and pigeons in how they respond in choice situations involving delayed and probabilistic reinforcers.