Purpose: This study focused on basic attentional impairments among persons with TBI who were behaviourally evaluated as suffering from either apathetic or disinhibition symptoms. Methods: Differences in orienting responses (ORs) and habituation rates were examined between patients (n = 18) and controls (n = 18) and between two TBI sub-groups: Apathetic (n = 9) and disinhibited patients (n = 9). Skin conductance responses were used to measure ORs and habituation rates. Results: The results revealed that the TBI patients did not differ from the control group in their ORs and habituation rate. However, marked differences emerged between the two TBI sub- groups. Apathetic patients presented attenuated ORs and more rapid habituation as compared to disinhibited patients. The findings indicate that when examining attentional impairments in the TBI population, different attentional patterns may counterbalance each other. Conclusion: As a result, the performance of the entire group may not adequately reflect the basic attentional impairments of its members. The study of attention deficits may benefit from consideration of systematic neuro- pathological differences within the TBI population.

brain injury; behavioural symptoms; attention; psychophysiology; orienting response

--