The effect of red light on backward masking in individuals with psychometrically defined schizotypy

Abstract

Introduction. Previous research has suggested that individuals with schizophrenia and their relatives show a change in backward masking performance with a red background that is in the opposite qualitative direction as that found in nonpsychiatric controls. The present study examines this effect in individuals with psychometrically defined schizotypy to explore the potential of this effect to be a useful new qualitative endophenotype for schizophrenia-spectrum traits. Methods. The Abbreviated Youth Psychosis At-Risk Questionnaire was used to screen a large number of undergraduates for schizotypy symptoms. A sample of 23 participants scoring high on this measure were compared to a sample of 26 controls on a location backward masking task that was presented on both red and green backgrounds. Results. Consistent with findings in patients with schizophrenia, the participants reporting a high number of schizotypy features showed a decrease in performance to the red (compared to green) background and the controls showed a nonsignificant increase in performance—although this finding was limited to the stimulus–onset asynchrony (SOA) value that approximated the SOA with the largest effect size in the previous schizophrenia study (69 ms). Conclusions. Although limited to one SOA, results extend earlier findings approximating this SOA to include a psychometrically defined schizotypy sample.