Attentional control in linguistic and nonlinguistic performance: A case study of a patient with head injury

Extensive linguistic and nonlinguistic error data collected from a head-injured patient, were analyzed for their significance for models of normal and pathological linguistic and cognitive organization and control. In the area of neuropathology, the patient was atypical with respect to subjects traditionally studied in brain-behavior research, in terms of brain lesion and symptom onset; on examination it was determined that he was not atypical when compared to more recently reported cases of mild head injury. In the area of classification the patient was atypical with respect to traditional aphasia classification as well as recent head-injury classification, in terms of the presence of "global" impairments in a context of unimpaired motor, sensory, and cognitive function; on examination it was determined that he was not atypical when compared in detail to patients with conduction aphasia or subcortical aphasia, rather than to syndrome descriptions. In the area of linguistic errors the patient was atypical in terms of the cross-modality distribution and multiple origins for errors, and his severe difficulty in correcting errors; on examination it was determined that his errors resembled those of conduction aphasic patients and normal subjects, and that the errors had a consistent pattern of origin in loss of selectivity and prevention of extraneous intrusion. In the area of nonlinguistic errors the patient was atypical in terms of presence of errors of action and perception; on examination it was determined that his nonlinguistic errors resembled those in many forms of pathological and normal error behavior, and that they, too, had a consistent pattern of origin in loss of selectivity and prevention of extraneous intrusion. Finally, in the area of attention the patient was atypical in terms of the presence of attention factors in his impaired behavior; on examination it was determined that his attention deficits were related to selectivity and resembled disturbances in many forms of pathological and normal behavior. The role of selective attention in the behavior of head injured subjects, other neurological subjects, and normal subjects, is discussed. Implications are explored for theoretical modelling of linguistic and cognitive function and for head injury rehabilitation.