Selective Attention and Intention in Schizophrenia

Abstract

Behavioral studies in humans have suggested that each hemisphere is important for mediating selective attention and response preparation (intention) in contralateral hemispace. In addition, there is evidence that the medial frontal lobe has a major role in response preparation. The aims of this study were to provide an experimental neuropsychological assessment of response preparation and selective attention in schizophrenia and to evaluate the hypotheses of medial frontal lobe dysfunction and/or hemispheric asymmetry in this disorder. Age and sex matched group of 21 chronic schizophrenic patients and 21 normal subjects were tested on a choice reaction time task in which they were given preliminary information about where a target stimulus would occur (selective attention) and which hand to use for responding (response preparation). Schizophrenic patients provided longer reaction times than normal controls (F=64.3; df=1,40; p<0.0001), which effect was more prominent when the target stimuli was presented in the right hemispace (F=4.1; df=1,40; p<0.05). All subjects, controls and patients, benefited from preparatory information regarding subsequent responses. The results of the attentional paradigm indicate, that the deficit of information processing in schizophrenia may affect left hemispheric mechanisms to a larger extent. According to the response preparation model, there was no evidence of medial frontal lobe impairment.