Previous research has shown a unique effect of red light on visual processing related to both schizophrenia and positive schizotypy. The current study examined whether this effect is influenced by sex in a more broadly-defined schizotypy sample. A location backward masking (BM) task with red, green, and gray backgrounds was administered to 34 undergraduate students (59% female) with a high score on the Schizotypal Personality Questionnaire (SPQ) and 38 students (50% female) with a low score. Results revealed that the group by color interaction was significant for the male participants, while it did not approach significance in the females. The male schizotypy participants showed a significant decrease in BM accuracy to the red (vs. green) background, while the male control participants showed a non-significant mean increase in accuracy. A decrease in accuracy to the red background in the male schizotypy participants was related to a higher score on the Social Anxiety subscale of the SPQ. Findings suggest that the previously reported schizophrenia red light effect is limited to males when examining a SPQ-defined sample, and appears to be primarily related to negative schizotypy symptoms. The red light effect continues to show promise as a new endophenotype for schizophrenia-spectrum disorders.
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