Response acquisition under targeted percentile schedules: a continuing quandary for molar models of operant behavior.

The number of responses rats made in a "run" of consecutive left-lever presses, prior to a trial-ending right-lever press, was differentiated using a targeted percentile procedure. Under the nondifferential baseline, reinforcement was provided with a probability of .33 at the end of a trial, irrespective of the run on that trial. Most of the 30 subjects made short runs under these conditions, with the mean for the group around three. A targeted percentile schedule was next used to differentiate run length around the target value of 12. The current run was reinforced if it was nearer the target than 67% of those runs in the last 24 trials that were on the same side of the target as the current run. Programming reinforcement in this way held overall reinforcement probability per trial constant at .33 while providing reinforcement differentially with respect to runs more closely approximating the target of 12. The mean run for the group under this procedure increased to approximately 10. Runs approaching the target length were acquired even though differentiated responding produced the same probability of reinforcement per trial, decreased the probability of reinforcement per response, did not increase overall reinforcement rate, and generally substantially reduced it (i.e., in only a few instances did response rate increase sufficiently to compensate for the increase in the number of responses per trial). Models of behavior predicated solely on molar reinforcement contingencies all predict that runs should remain short throughout this experiment, because such runs promote both the most frequent reinforcement and the greatest reinforcement per press. To the contrary, 29 of 30 subjects emitted runs in the vicinity of the target, driving down reinforcement rate while greatly increasing the number of presses per pellet. These results illustrate the powerful effects of local reinforcement contingencies in changing behavior, and in doing so underscore a need for more dynamic quantitative formulations of operant behavior to supplement or supplant the currently prevalent static ones.     

Control over response number by a targeted percentile schedule: reinforcement loss and the acute effects of d-amphetamine.

Two fixed-consecutive-number-like procedures were used to examine effects of acute d-amphetamine administration on control over response number. In both procedures, rats were required to press the left lever at least once and then press the right lever to complete a trial. The consecutive left-lever presses on each trial comprised a "run." Under the targeted percentile schedule, reinforcement was provided if the current run length was closer to the target length (16) than half of the most recent 24 runs. This differentially reinforced run length while holding reinforcement probability constant at .5. A second group acquired the differentiation under the targeted percentile schedule, but were then shifted to a procedure that yoked reinforcement probability by subject and run length to that obtained under the targeted percentile schedule. The two procedures generated practically identical control run lengths, response rates, reinforcement probabilities, and reinforcement rates. Administration of d-amphetamine disrupted percentile responding to a greater degree than yoked control responding. This disruption decreased reinforcement frequency less in the former than the latter procedure. The similar baseline responding under these two procedures suggests that this difference in sensitivity was due to behavioral adjustments to drug prompted by reduction of reinforcement density in the yoked control but not the percentile schedule. These adjustments attenuate the drug's effects under the former, but not the latter, procedure.     

Behavior of rats under fixed consecutive number schedules: effects of drugs of abuse.

Four rats responded under a simple fixed consecutive number schedule in which eight or more consecutive responses on the run lever, followed by a single response on the reinforcement lever, produced the food reinforcer. Under this simple schedule, dose-response curves were determined for diazepam, morphine, pentobarbital, and phencyclidine. The rats were then trained to respond under a multiple fixed consecutive number schedule in which a discriminative stimulus signaled when the response requirement on the run lever had been completed in one of the two fixed consecutive number component schedules. Under control conditions, the percentage of reinforced runs under the multiple-schedule component with the discriminative stimulus added was much higher than the percentage of reinforced runs under the multiple-schedule component without the discriminative stimulus. All of the drugs decreased the percentage of reinforced runs under each of the fixed consecutive number schedules by increasing the conditional probability of short run lengths. This effect was most consistently produced by morphine. The drugs produced few differences in responding between the multiple fixed consecutive number components. Responding under the simple fixed consecutive number schedule, however, was affected at lower doses of the drugs than was responding under the same fixed consecutive number schedule when it was a component of the multiple schedule. This result may be due to the difference in schedule context or, perhaps, to the order of the experiments.     

Shock as a signal for shock or no-shock: a feature-negative effect in conditioned suppression.

Rats were trained in conditioned suppression discriminations where shock at the beginning of a trial signaled either shock or no-shock at the end of the trial. In the shock-positive condition, shock at the beginning of a presentation of white noise signaled that noise would end with shock; noise that did not begin with shock did not end with shock. In the shock-negative discrimination, shock at the beginning of noise signaled that noise would not end with shock; presentations of noise that did not begin with shock ended with shock. In shock-random training, shock at the beginning of noise did not reliably signal whether the noise presentation would or would not end with shock. Most subjects in shock-negative training quickly developed a differential pattern of suppression on positive (shock reinforced) trials and no suppression on negative (nonreinforced) trials. The shock-positive discrimination was much more difficult to establish and was not acquired by the majority of the rats. This "feature-negative" effect is a clear exception to the general superiority of feature-positive learning commonly observed in discriminations based on a single distinguishing feature. The results are discussed in terms of Pavlovian stimulus-shock contingencies in the shock-positive and shock-negative paradigms, which appear to favor rapid development of the shock-negative discrimination.     

特征捆绑机制的理论模型

捆绑问题被认为是认知科学和神经科学的中心问题之一,对心理过程的认知神经机制研究起到了重要推动作用。特征捆绑机制研究有认知和神经科学两大范式。特征整合论在认知理论中最具代表性,形式理论修正了其在错觉性结合测量等方面的不足,双阶段理论突出了前注意捆绑。时间同步性理论是影响最大的捆绑理论,神经网络模型为捆绑机制提出了更具体的结构模型。两大范式的整合及由低级认知过程向高级心理过程的深化可能是今后捆绑机制研究的重点     

核心知识系统及其对相关研究的启示

核心知识系统出现于人类个体发展和种系发展的早期,在人类复杂认知能力的发生发展中起着建构模块的作用。该文以表征物体和数量关系的两类核心知识系统的性质及二者在儿童的“数”概念形成和成人的数学思维中所起的作用为例,综述了以灵长类动物、婴儿、儿童和成人为被试的研究证据,并进而提出了核心知识系统给相关研究带来的若干启示。     

"感"·"象"·"数"--《周易》经传象数观念的哲学人类学释读

象数观念是<周易>经传乃至易学中的基础和核心观念.历来对象数观念的理解和解释,往往局限于象数观念本身,而对<周易>经传的产生背景、以及其中的另一个重要观念--"感",则关注不够.本文从哲学人类学的视角,在考察<周易>经传的产生背景以及"感"、"象"、"数"三者之间关系的基础上,认为<周易>经传中的象数观念其实是原始时代的感性具体的思维方式及其宇宙观的积淀.具体说来,"数"也是"象",它们本来都是"互渗"或"交感"的中介;换句话说,<周易>经传象数观念的最终依据其实是感;象数因感而蕴涵着向天道观和伦理观发挥的可能性.     

Left to right: representational biases for numbers and the effect of visuomotor adaptation

Adaptation to right-shifting prisms improves left neglect for mental number line bisection. This study examined whether adaptation affects the mental number line in normal participants. Thirty-six participants completed a mental number line task before and after adaptation to either: left-shifting prisms, right-shifting prisms or control spectacles that did not shift the visual scene. Participants viewed number triplets (e.g. 16, 36, 55) and determined whether the numerical distance was greater on the left or right side of the inner number. Participants demonstrated a leftward bias (i.e. overestimated the length occupied by numbers located on the left side of the number line) that was consistent with the effect of pseudoneglect. The leftward bias was corrected by a short period of visuomotor adaptation to left-shifting prisms, but remained unaffected by adaptation to right-shifting prisms and control spectacles. The findings demonstrate that a simple visuomotor task alters the representation of space on the mental number line in normal participants.     

A colorful walk on the mental number line: Striving for the right direction

Verguts and Van Opstal [Verguts, T., & Van Opstal, F. (2008). A colorful walk, but is it on the mental number line? Reply to Cohen Kadosh, Tzelgov, and Henik, Cognition, 106, 558-563] cleverly explained the results of Cohen Kadosh, Tzelgov, and Henik [Cohen Kadosh, R., Tzelgov, J., & Henik, A. (2008). A synesthetic walk on the mental number line: The size effect, Cognition, 106, 548-557] as a result of different association strength between the size of a number and its color in synesthesia. Here we present three challenges to their alternative explanation, and support our original suggestion.     

The SNARC effect does not imply a mental number line

In this study, we directly contrast two approaches that have been proposed to explain the SNARC effect. The traditional direct mapping account suggests that a direct association exists between the position of a number on the mental number line and the location of the response. On the other hand, accounts are considered that propose an intermediate step in which numbers are categorized as either small or large between the number magnitude and the response representations. In a magnitude comparison task, we departed from the usual bimanual left/right response dimension and instead introduced the unimanual close/far dimension. A spatial-numerical association was observed: small numbers were associated with a close response, while large numbers were associated with a far response, regardless of the movement direction (left/right). We discuss why these results cannot be explained by assuming a direct mapping from the representation of numbers on a mental number line to response locations and discuss how the results can be explained by the alternative accounts.