任务切换机制研究的理论争议与整合

任务切换是执行控制的一种重要功能。切换代价是量化执行控制持续时间的指标。并广泛应用于各个研究领域。但是切换代价在多大程度上体现了执行控制的作用,仍然还存在争论．当前主要存在任务设置重构、任务设置惯性和联结竞争三种理论。本文首先介绍了三种理论的基本观点和实验证据,以及对任务切换加工机制的分析;其次阐明了对三种理论进行整合的相关研究;最后分析了进一步研究的方向。     

Emotionally controlled decision-making and a gene variant related to serotonin synthesis in women with borderline personality disorder

The Iowa Gambling Task (IGT) was used to examine (i) social decision-making in women with borderline personality disorder (BPD), and (ii) the relationship between impaired decision-making and the tryptophan hydroxylase-1 (TPH-1) gene, involved in serotonin synthesis. Forty-two women with BPD and a history of suicide attempts were genotyped, and the frequency of a TPH-1 haplotype previously uniquely associated with BPD was calculated. The BPD group scored significantly lower than a control group in the IGT. Furthermore, the TPH-1 haplotype displayed a significantly higher frequency in BPD participants with impaired decision making, compared to BPD participants with normal scores. These findings suggest that impaired decision-making as determined by the IGT is a feature of BPD and may be (i) associated with serotonin dysfunction, and (ii) possibly relevant for suicidal behavior.     

Neural correlates of Traditional Chinese Medicine induced advantageous risk-taking decision making

This fMRI study examined the neural correlates of the observed improvement in advantageous risk-taking behavior, as measured by the number of adjusted pumps in the Balloon Analogue Risk Task (BART), following a 60-day course of a Traditional Chinese Medicine (TCM) recipe, specifically designed to regulate impulsiveness in order to modulate risk-taking behavior. The 14 participants recruited for this study were randomly assigned to the experimental and control groups and the TCM recipe (Panax, 520 mg; Astragalus membranaceous Bunge, 520 mg; Masnetitum, 840 mg; Ostrea gigas Thumb, 470 mg; Thinleaf Milkwort Root Radix Polygalae, 450 mg; and Os Draconis, 470 mg) was administered, as a diet supplement, to the seven participants in the experimental group. The neural activity of the two groups was monitored by a 3T MRI scanner, before and after the 60-day treatment. Associated with the improved advantageous risk-taking behavior seen in the experimental group, significantly stronger blood oxygenation level dependent (BOLD) responses were observed in the bilateral dorsolateral prefrontal cortex (DLPFC), left putamen, left thalamus, right insula, and right anterior cingulate cortex (ACC), regions which have previously been reported as being involved in risk-taking decision making. The effect of the TCM in improving advantageous risk-taking decision making appears to have been related to the enhanced efficiency of the cognitive affective system, the PFC–ACC–insula–striatum network, which functions to inhibit impulsiveness, to sensitize reward-related information, and to allow the opportunity, during risk estimation, to evaluate potential gains and losses. The findings of this study suggest that interventions acting on factors modulating risk-taking decision making could have a beneficial effect in terms of optimizing risk-taking behavior.     

转换加工研究回顾

任务转换是人类认知活动的基本方式,其过程转换加工为中央执行系统的重要功能。转换加工在工作记忆中体现为控制竞争同一认知资源的两项任务之间相互转换的过程。执行转换任务的反应时比执行重复任务的反应时更长,两反应时之差为转换代价。行为实验和神经生理学实验在转换加工的研究范式、转换代价的成分以及执行控制的理论等领域取得一定成果,但也存在诸多争议。事件相关电位和功能磁共振成像技术的联合使用能直观地反映大脑转换加工的时、空动态变化特征,将为转换加工的进一步研究提供证据     

中小学生注意转换能力的发展研究

采用任务转换范式考察了108名中小学生的注意转换能力。反应—线索间距和线索—目标间距都分为200ms和2000ms两种水平。结果发现：（1）一般转换条件下,小5学生、初2学生和高2学生的定势选择速度相同,小5学生的定势选择正确性比初2学生和高2学生低;特定转换条件下,短时CTI下小5学生的定势转换速度比初2学生和高2学生慢,长时CTI下小5学生的定势转换速度比初2学生和高2学生快,初2学生的定势转换正确性比高2学生低;（2）一般转换条件下,任务定势重组在任务转换中作用不大,任务定势惯性在任务转换中起作用;特定转换条件下,任务定势重组和任务定势惯性在任务转换中的作用都不大。     

AN ANALYSIS OF A GROUP TEACHING PROCEDURE FOR PERSONS WITH DEVELOPMENTAL DISABILITIES

This study evaluated whether a concurrent group teaching procedure, in which all students respond simultaneously, could be used for persons with moderate or severe mental retardation. The teaching procedure used was the Task Demonstration Model, a program based on stimulus-control research and the fading techniques of behavioral psychology. Three teachers and three groups of students participated. Results showed that the teachers increased their rates of questions and instructions, positive feedback, and use of functional materials, but they reduced their rate of prompts to almost zero. Students increased their percentage and rate of correct responding as well as their engaged time. In addition, maladaptive responding, for which there were never any direct consequences, decreased from 45% to 10% for 8 of the 14 students. Results are discussed primarily in two areas: (a) changing stimulus control from teacher prompts to critical elements of the items being taught, and (b) reasons for the reduction of maladaptive behavior for 8 of the subjects.     

Increasing the variability of response sequences in pigeons by adjusting the frequency of switching between two keys.

Three experiments compared the amounts of behavioral variability generated with two reinforcement rules. In Experiments 1 and 2 pigeons received food whenever they generated a sequence of eight pecks, distributed over two keys, provided that the sequence contained a certain number of change-overs between the keys. Although no variability was required-the birds could obtain all reinforcers by repeating the same sequence-the pigeons emitted a large number of different sequences. In Experiment 3 pigeons received food whenever they generated a sequence that had not occurred during the last 25 trials. After prolonged training, the birds showed more sequence variability than in the first two experiments. The analysis of the internal structure of the response sequences revealed that, in general, (a) the location of the first peck was highly stereotyped; (b) as the trial advanced, the probability of switching to the initially preferred key decreased whereas the probability of switching to the other key increased; and (c) a first-order Markov chain model with transition probabilities given by a logistic function accounted well for the internal structure of the birds' response sequences. These findings suggest that, to a large extent, the variability of response sequences is an indirect effect of adjustments in changeover frequency.     

Pure timing in temporal differentiation

Temporal control appears to depend on whether the critical durations are those of stimuli or those of responses. Stimulus timing (temporal discrimination) supports Weber's law, whereas response timing (temporal differentiation) indicates decreasing relative sensitivity with longer time intervals. The two types of procedure also yield different conclusions in scaling experiments designed to study the functional midpoint of two or more durations (temporal bisection procedures). In addition, the fractional-exponent power relation between emitted and required duration usually found with animals in differentiation experiments conflicts with deductions from formal analyses. The experiment reported here derived from considering differentiation arrangements as schedules of reinforcement. When analyzed from this perspective, the procedures are tandem schedules involving a required pause followed by a response, and it is the pause alone that involves temporal control. A choice procedure separated timing from responding, and enabled observations of pause timing in isolation. Pure temporal control in differentiation consisted of linear overestimation of the standard duration, and Weber's law described sensitivity. These results indicate that the two problems, the fractional-exponent power relations and the apparently different nature of sensitivity in differentiation and discrimination, disappear when temporal control is observed alone in differentiation.     

Implicit achievement motive limits the impact of task difficulty on effort-related cardiovascular response

In contrast to the motive literature, motivational intensity theory predicts that the implicit achievement motive (nAch) should only exert an indirect impact on effort by limiting the impact of task difficulty. To contrast these two views, sixty-eight participants with a low or high nAch performed an easy or difficult arithmetic task. Effort was assessed using cardiac pre-ejection period (PEP). Supporting motivational intensity theory’s view, PEP response was low in both easy-task conditions but stronger in the high-nAch group than in the low-nAch group in the difficult task. These findings suggest that nAch exerts an indirect effect on effort investment by setting the maximally justified effort instead of directly determining the amount of effort that is invested to satisfy the motive.     

Reproducibility and a unifying explanation: Lessons from the shape bias

The goal of science is to advance our understanding of particular phenomena. However, in the field of development, the phenomena of interest are complex, multifaceted, and change over time. Here, we use three decades of research on the shape bias to argue that while replication is clearly an important part of the scientific process, integration across the findings of many studies that include variations in procedure is also critical to create a coherent understanding of the thoughts and behaviors of young children. The “shape bias,” or the tendency to generalize a novel label to novel objects of the same shape, is a reliable and robust behavioral finding and has been shown to predict future vocabulary growth and possible language disorders. Despite the robustness of the phenomenon, the way in which the shape bias is defined and tested has varied across studies and laboratories. The current review argues that differences in performance that come from even seemingly minor changes to the participants or task can offer critical insight to underlying mechanisms, and that working to incorporate data from multiple labs is an important way to reveal how task variation and a child’s individual pathway creates behavior—a key issue for understanding developmental phenomena.