A computer model is presented that performs 4 tasks sometimes impaired by frontal damage: motor sequencing, the Stroop task, the Wisconsin Card Sorting Test, and a context memory task. In each task, patterns of performance typical of frontal-damaged patients are shown to result from the same type of damage to the model, specifically, weakening of associations among elements in working memory. The simulation shows how a single underlying type of damage could result in impair-ments on a variety of seemingly distinct tasks. Furthermore, the hypothesized damage affects the processing components that carry out the task rather than a distinct central executive. Although the frontal lobe constitutes as much as one third of the human cortex and is often referred to as the seat of higher intellectual function, its functions are poorly under-stood in terms of current theories of cognition. Patients with damage to the frontal cortex have difficulty with a wide range of tasks, from the execution of simple manual sequences (Luria, 1965) to sorting stimuli into abstract categories (Milner, 1963). But although the form of these deficits may vary from task to task, there are family resemblances among the ways in which frontal-damaged patients fail. One of the challenges of theorizing in this area has been to account for both the similarities and differences among the tasks failed by frontal-damaged patients and for the characteristic ways in which they are failed. Explanations of particular frontal impairments often fail to take into account the similarities and instead propose hypotheses specific to each task. At-tempts to provide unified accounts of frontal function usually depend on central executives that are dissociated from the mechanisms used to perform the tasks themselves. In the present article, we attempt to capture a commonality among the deficits of frontal-damaged patients that may serve as a basis for these family resemblances. In doing so, we provide a unified account of frontal lobe dysfunction and one in which the hypothesized damage does not affect a central executive mechanism.
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