Task-switch costs subsequent to cue-only trials

There is abundant evidence that there is a performance cost associated with switching between tasks. This “switch cost” has been postulated to be driven by task performance on the preceding trial, but recent research challenges any necessary role of previous task performance in driving the cost. Across three experiments, we investigated whether it is difficult to switch from a task that was prepared but never performed. We replicated the finding of a switch cost following cue-only trials (involving no task performance) whilst controlling for a potential cue-switching confound. This cost was larger than that following completed trials when preparation interval was short (300?ms), and it reduced significantly with a longer preparation interval (1000?ms) on the current trial. We also found that preparing only to attend to a particular visual dimension (colour or shape) was sufficient to drive a significant subsequent switch cost, which appeared to be residual in nature; we speculate that this cost may reflect the persistence of unfulfilled task intentions and/or a strategic slowing when consecutive intentions conflict.     

Learning to allocate limited time to decisions with different expected outcomes

The goal of this article is to investigate how human participants allocate their limited time to decisions with different properties. We report the results of two behavioral experiments. In each trial of the experiments, the participant must accumulate noisy information to make a decision. The participants received positive and negative rewards for their correct and incorrect decisions, respectively. The stimulus was designed such that decisions based on more accumulated information were more accurate but took longer. Therefore, the total outcome that a participant could achieve during the limited experiments’ time depended on her “decision threshold”, the amount of information she needed to make a decision. In the first experiment, two types of trials were intermixed randomly: hard and easy. Crucially, the hard trials were associated with smaller positive and negative rewards than the easy trials. A cue presented at the beginning of each trial would indicate the type of the upcoming trial. The optimal strategy was to adopt a small decision threshold for hard trials. The results showed that several of the participants did not learn this simple strategy. We then investigated how the participants adjusted their decision threshold based on the feedback they received in each trial. To this end, we developed and compared 10 computational models for adjusting the decision threshold. The models differ in their assumptions on the shape of the decision thresholds and the way the feedback is used to adjust the decision thresholds. The results of Bayesian model comparison showed that a model with time-varying thresholds whose parameters are updated by a reinforcement learning algorithm is the most likely model. In the second experiment, the cues were not presented. We showed that the optimal strategy is to use a single time-decreasing decision threshold for all trials. The results of the computational modeling showed that the participants did not use this optimal strategy. Instead, they attempted to detect the difficulty of the trial first and then set their decision threshold accordingly.     

HUMAN RESPONDING ON RANDOM‐INTERVAL SCHEDULES OF RESPONSE‐COST PUNISHMENT: THE ROLE OF REDUCED REINFORCEMENT DENSITY

An experiment with adult humans investigated the effects of response‐contingent money loss (response‐cost punishment) on monetary‐reinforced responding. A yoked‐control procedure was used to separate the effects on responding of the response‐cost contingency from the effects of reduced reinforcement density. Eight adults pressed buttons for money on a three‐component multiple reinforcement schedule. During baseline, responding in all components produced money gains according to a random‐interval 20‐s schedule. During punishment conditions, responding during the punishment component conjointly produced money losses according to a random‐interval schedule. The value of the response‐cost schedule was manipulated across conditions to systematically evaluate the effects on responding of response‐cost frequency. Participants were assigned to one of two yoked‐control conditions. For participants in the Yoked Punishment group, during punishment conditions money losses were delivered in the yoked component response independently at the same intervals that money losses were produced in the punishment component. For participants in the Yoked Reinforcement group, responding in the yoked component produced the same net earnings as produced in the punishment component. In 6 of 8 participants, contingent response cost selectively decreased response rates in the punishment component and the magnitude of the decrease was directly related to the punishment schedule value. Under punishment conditions, for participants in the Yoked Punishment group response rates in the yoked component also decreased, but the decrease was less than that observed in the punishment component, whereas for participants in the Yoked Reinforcement group response rates in the yoked component remained similar to rates in the no‐punishment component. These results provide further evidence that contingent response cost functions similarly to noxious punishers in that it appears to suppress responding apart from its effects on reinforcement density.     

Maternal expression of communicative intentions and pragmatic fine tuning in early infancy

This study focuses on pragmatic characteristics of infant-directed speech and pragmatic fine tuning during the first 18 months of life. The subjects of the study were a mother–child dyad involved in a longitudinal/observational study in a familial context. Audiovisual recordings were transcribed according to the conventions of the Child Language Data Exchange System ([MacWhinney, 2000] and [MacWhinney and Snow, 1990]). The Ninio and Wheeler's (1988) system for coding communicative intentions was adapted.The results of this research show that most of the communicative exchanges identified at 14, 20 and 32 months by Snow, Pan, Imbens-Bailey, and Herman (1996) appear in mother–child interaction from the beginning, while other communicative interchanges appear later. With respect to speech acts, the results highlight, from an early age, the general tendencies discussed by Snow et al. and some novelties. Interestingly, changes in some pragmatic measures were identified around 8 months of age, and the appearance of new communicative interchanges also took place around this age. These changes are interpreted as maternal adjustments to the child's communicative competence.     

汉-英双语者言语理解中语码切换的机制——来自亚词汇水平的证据

以汉字义符和英文词后缀为对象,考察了汉-英双语者语码切换的机制及切换代价的来源。结果表明:(1)在亚词汇水平上,汉字义符和英文词后缀影响字词认知的过程,但对语码切换代价的影响不显著,支持语码切换与任务转换的发生机制相同的观点。(2)语言熟练程度是影响语码切换代价及切换代价不对称性的主要原因。整个研究表明,在亚词汇水平上,语码切换与任务转换的实质相同。参考任务转换中切换代价的来源,归纳了语码切换代价的可能来源。     

延迟时间与反应设置对任务切换的影响

采用任务线索范式,探讨了在不同反应设置条件下,延迟时间对任务切换的影响,以揭示在延迟时间内之前任务设置延迟的认知加工。以切换代价为主要测量指标,结果表明,反应设置和延迟时间的主效应均不显著,但是二者的交互作用显著。简单效应分析发现,在双向设置条件下,切换代价随着延迟时间的延长而显著减少,但是在单向设置条件下无显著差异。这说明,在任务切换中反应设置对延迟时间的影响效应具有调节作用。由此可见,在延迟时间内之前任务设置延迟的是反应设置。     

论医疗权及其实践

患者的医疗权可以表现为宪法上的应然权利和实践中的实然权利.在具体医疗实践中,患者获得公正、必须和费用节省的医疗服务的权利,是以患者支付医疗费用为前提的.在特定情况下,虽然患者无支付能力,也可以享有医疗权.患者有拒绝医疗的权利.     

当前我国医患关系的思考

手术同意书使用范围的扩大化是目前医患关系紧张的一个表现,患者医疗费用负担过重、医患间缺少沟通、医疗保障制度建设滞后是医患关系紧张的主要原因,解决上述问题是建立和谐医患关系的关键。     

Hand Switching Costs are not Uniform Across Response Components

We investigated the extent to which a complex finger sequence impacts on hand switching costs in a sequential action. Response component latencies (premotor, motor, and movement) were compared in no-switch (same finger performed the action of pressing and reaching) and switch conditions (pressing with one finger and completing the reaching action with the homologous finger from the other hand). Results showed that the switch condition presented longer latency for premotor and movement components. For the motor component, however, switch condition was faster. This expands the previous literature investigating switching costs using simple finger movements in more complex tasks. A mechanical explanation of the interplay between response subcomponents is provided to explain the inversion of response pattern for the motor component.     

Sunk Cost and Commitment to Dates Arranged Online

The influence of prior, irretrievable, investment (sunk cost) on commitment to a date arranged online was investigated. Participants were recruited from an undergraduate population. There were 145 participants (86 female) with a mean age of 19.42 years. Participants took part in a computer simulation of the process of arranging a date online. Participants invested one of five amounts of sunk cost into this process. Participants were then presented with the choice of attending the date arranged online or attending a (superior) blind date. Participants chose how much time that they wanted to commit to the (inferior) date arranged online. Results revealed a significant sunk cost effect (p = 0.003). The implications of the sunk cost effect having an influence over human relationships are discussed.