Background: schizophrenic patients show strong deficits over a broad range including bhigherQ cognitive and executive functions and blowerQ, basic sensory information processing. The latter deficits might cause deficits on higher, cognitive levels. Using a new backward masking paradigm, shine-through, we could show that target processing is strongly impaired in adult schizophrenic patients whereas basic visual functions, such as figure-ground-segmentation and feature binding, are spared.
Methods: to evaluate whether the shine-through paradigm is also suitable to show visual information processing deficits in adolescents with psychotic disorders. We presented a vernier target that was followed by a grating mask. A vertical vernier consists of two bars that are slightly offset in the horizontal direction randomly either to the left or to the right. Observers have to indicate this offset direction. We determined the stimulus onset asynchrony (SOA) between the vernier and the grating onset for 34 adolescents (mean age=15.7 ) : 12 with schizophrenia spectrum disorders, 7 adolescents at high risk of psychosis, and a control group of 14 adolescents.
Results: our preliminary data show that adolescents with psychotic disorders need SOAs of 97.7 ms to reach a comparable performance level whereas adolescents at high risk for psychosis need SOAs of only 55.7 ms, and controls of 16.5 ms.
Conclusions: our results suggest that backward masking is a promising tool to detect vulnerability to schizophrenia spectrum disorders with early deficits possibly affecting later cognitive or executive functions.