Spatial and semantic inhibitory processing in schizophrenia.

Two experiments assessed inhibitory mechanisms associated with the posterior and anterior attention networks in schizophrenia. Experiment 1 assessed the inhibition of return effect of the posterior network. Both healthy adults and schizophrenic adults showed inhibition of return, suggesting that this inhibitory mechanism of visual orienting is preserved in schizophrenia. Experiment 2 assessed semantic inhibition, which supposedly taps the anterior network, in a lexical-decision task. Healthy adults showed semantic inhibition effects in both visual fields. Schizophrenic adults showed semantic inhibition effects when targets were presented to the left visual field, involving the right hemisphere. However, semantic facilitation rather than inhibition was observed when targets were presented to the right visual field, involving the left hemisphere. These results reflect left hemisphere dysfunction associated with deficits in attentional control in schizophrenia.