Background: Schizophrenic patients show strong deficits over a broad range including "higher" cognitive and executive functions and "lower", 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 42 adolescents (mean age=15.7 ) : 12 with schizophrenia spectrum disorders, 9 adolescents at high risk of psychosis, and a control group of 16 healthy adolescents and 5 with non psychotic disorders.
Results: Our preliminary data show that adolescents with psychotic disorders need SOAs of 111 ms to reach a comparable performance level whereas adolescents at high risk for psychosis need SOAs of only 57 ms, and controls of 21 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.