E prime software version 1.2

Subjects performed a computerized version of the Stroop color-naming task (52 (link)). Stimuli consisted of three words: “RED,” “GREEN,” or “BLUE,” displayed in one of the corresponding colors. Trials were designated as either “congruent” or “incongruent,” where incongruent trials reflected a difference between the word and the color of the word. Subjects were instructed to indicate the color and ignore the word. They were instructed to respond as quickly and as accurately as possible and responses were recorded by button press. An IFIS-SA system (in vivo, Orlando, Florida) running E-Prime software (version 1.2; Psychology Software Tools, Pittsburgh, Pennsylvania) was used to control stimulus delivery and record responses and reaction times. The event-related design consisted of three runs of 88 trials per run (~30% incongruent, 70% congruent; to increase conflict effect, the numbers of incongruent trials were less than congruent trials). The 3 s trials were comprised of a word stimulus for 1.5 s and a fixation cross for 1.5 s. Both SZ and HC completed a baseline session and a second session, 6 weeks later, corresponding to pre and post antipsychotic medication in SZ. All participants completed a practice run in the laboratory before each scanning session.