No abstract

A subset of right brain-damaged patients shows leftward overextension in the line extension task. It has been argued that this deficit can be attributed to a distortion of the metric structure of perceived space (spatial anisometry). We investigated whether spatial distortion of static stimuli is associated with a corresponding misperception of perceived acceleration of moving stimuli. Seven right brain-damaged patients with spatial anisometry and two control groups were presented with stimuli moving leftwards or rightwards along the horizontal axis at different rates of acceleration. They were asked to estimate whether the target accelerated or decelerated. The anisometric group judged the perceived acceleration of leftward motions as less than that of rightward motions. The magnitude of the misperception of acceleration correlated positively with relative left overextension in the line extension task and with rightward displacement error in the line bisection task. This directional difference is in line with the predictions of the spatial anisometry hypothesis.

Attentional processes play a central role in information selection, which is impaired in schizophrenic patients. In the present study, we attempted to characterize the attentional performance of chronic schizophrenics using a computerized assessment of the multiple components of attentional function. Two comparable samples, consisting, respectively, of out-patients and in-patients, were tested in order to assess the effect of chronic institutionalization. Twenty-four subjects (half in-patients and half out-patients) fulfillling DSM-IV criteria for schizophrenia were examined with a standard computerized battery for the assessment of attention, namely Testbatterie zur Aufmerksamkeitsprufung (TAP). Both groups were impaired on all measures of attentional processing (in terms of both reaction times and number of errors). There were no significant differences in attentional performance between in-and out-patients. In conclusion, the present findings confirm the presence of pervasive attentional dysfunction in chronic schizophrenia; the lack of significant differences in performance between in-and out-patients supports the hypothesis that the cognitive deficits are inherently associated with the illness and cannot be attributed to environmental/social factors.