Cognitive theory and the study of everyday action disorders after brain damage

This article addresses the question of why some patients with severe traumatic brain injury are unable to carry out even simple, routine activities of daily living without becoming confused and making errors. The argument is developed that such a condition represents “frontal apraxia,” a disorder of executive function defined here as an impairment in the on-line activation of action plans. Two alternatives to this account are considered. One involves a disturbance of attentional control of action; the second involves loss or degradation of the conceptual knowledge base for action. The types of assessments required for differentiating between these alternatives are described and exemplified with reference to specific cases.