Defining task-set reconfiguration: The case of reference point switching

Some researchers argue that task switching involves task-set reconfiguration-that is, changing the existing task set to perform a different task. Although this idea is intriguing, it is often unclear what is reconfigured and which processes are involved in reconfiguration. We addressed these issues by defining task sets, identifying differences between them, and obtaining evidence that was diagnostic of reconfiguration. In two experiments, subjects performed relative judgment tasks that involved comparing a target with a reference point that repeated or switched across trials. The task was the same on every trial, but the task set was not, because a task-set parameter-the reference point-had to be changed. Target-reference point distance effects that changed with the reference point provided diagnostic evidence that reconfiguration occurred, and this reconfiguration led to switch costs. We discuss how our approach can be generalized to define reconfiguration more clearly in other task-switching situations. nt|mis|This research was supported by Grants BCS 0133202 and BCS 0446806 from the National Science Foundation to G.D.L.     

The Left Hand Doesn't Know What the Right Hand Is Doing: The Disruptive Effects of Attention to the Hands in Skilled Typewriting

ABSTRACT— Everyone knows that attention to the details disrupts skilled performance, but little empirical evidence documents this fact. We show that attention to the hands disrupts skilled typewriting. We had skilled typists type words preceded by cues that told them to type only the letters assigned to one hand or to type all of the letters. Cuing the hands disrupted performance markedly, slowing typing and increasing the error rate (Experiment 1); these deleterious effects were observed even when no keystrokes were actually inhibited (Experiment 3). However, cuing the same letters with colors was not disruptive (Experiment 2). We account for the disruption with a hierarchical control model, in which an inner loop controls the hands and an outer loop controls what is typed. Typing letters using only one hand requires the outer loop to monitor the inner loop's output; the outer loop slows inner-loop cycle time to increase the likelihood of inhibiting responses with the unwanted hand. This produces the disruption.     

Emotional Closeness as a Mediator of the Effect of Genetic Relatedness on Altruism

Inclusive fitness theory has been used to explain the overall pattern of altruistic behavior. However, this theory does not address the proximal causes of altruism. The purpose of the present study was to increase the understanding of altruism by testing a model that includes both ultimate and proximate causes. In particular, emotional closeness was tested as a mediator of the effect of genetic relatedness on altruistic behavior. This was accomplished by having college students choose which of their family members they would most likely provide with life-saving assistance. As expected, results showed that emotional closeness is an important proximal cause of altruism that partially mediates the effect of genetic relatedness on willingness to act altruistically.     

Thyroid hormones,psychophysiological reactivity,and anxiety

Thirty-eight adults were assigned to three groups: posttreatment hyperthyroid (n=13), low euthyroid (n=12), and high euthyroid (n=13). Physiological and subjective responses to three anxiety-induction procedures—public speaking, personally distressing imagery, and threat of shock—were compared across groups. Although there were differences across stressors for physiological and subjective measures, group differences were not detected. Results are discussed with regard to the risk for residual anxiety following treatment for hyperthyroidism and the possible influence of thyroid function on the etiology or maintenance of anxiety.     

The role of attention in automatization: Does attention operate at encoding, or retrieval, or both?

In this research, we investigated whether attention operates in the encoding of automatized information, the retrieval of automatized information, or in both cases. Subjects searched two-word displays for members of a target category in focused-attention or divided-attention conditions that were crossed with block (training vs. transfer). To see whether subjects encoded all available items or only attended items, we compared performance for subjects in different training conditions but in the same transfer condition. Subjects encoded attended items. To see whether subjects retrieved all the items they had in memory, or only items associated with that to which they were attending at retrieval, we compared performance for subjects in the same training conditions but in different transfer conditions. Subjects retrieved attended items. Attention was found to operate at both encoding and retrieval. These findings support the instance theory of automaticity, which predicts the role of attention at encoding and retrieval     

On the ability to inhibit simple and choice reaction time responses: a model and a method

This article reports four experiments on the ability to inhibit responses in simple and choice reaction time (RT) tasks. Subjects responding to visually presented letters were occasionally presented with a stop signal (a tone) that told them not to respond on that trial. The major dependent variables were (a) the probability of inhibiting a response when the signal occurred, (b) mean and standard deviation (SD) of RT on no-signal trials, (c) mean RT on trials on which the signal occurred but subjects failed to inhibit, and (d) estimated RT to the stop signal. A model was proposed to estimated RT to the stop signal and to account for the relations among the variables. Its main assumption is that the RT process and the stopping process race, and response inhibition depends on which process finishes first. The model allows us to account for differences in response inhibition between tasks in terms of transformations of stop-signal delay that represent the relative finishing times of the RT process and the stopping process. The transformations specified by the model were successful in group data and in data from individual subjects, regardless of how delays were selected. The experiments also compared different methods of selecting stop-signal delays to equate the probability of inhibition in the two tasks.     

Effects of methylphenidate on inhibitory control in hyperactive children

This study investigated the effects of methylphenidate (MPH) on inhibitory control in hyperactive children. A double-blind, placebo-control, within-subject (crossover) design was used in which 12 children, between 6 and 11 years of age, were each tested four times in each drug condition: 0.3 mg/kg and 1.0 mg/kg of methylphenidate, and placebo. Dependent measures included (a) the probability of inhibiting responses to a primary choice reaction time task given a stop signal, on the Stopping Task, and (b) response latency and errors on the Matching Familiar Figures Test (MFFT). MPH improved the efficiency of the central inhibitory mechanism by speeding the inhibitory process, thereby affording the children greater control over their actions and enabling them to increase the probability with which they inhibited responses given a stop signal. MPH increased response latency but did not reduce errors on the MFFT, and observation of the children's task performance highlighted the interpretive problems associated with this task. Performance on both tasks was better at a dosage of 1.0 mg/kg than at 0.3 mg/kg.