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137. Impaired Auditory Oddball Task Performance May Reflect Disordered Perceptual Suppression In Psychosis
Schizophrenia is commonly associated with aberrant perceptual processing, especially in the auditory domain as exemplified by auditory hallucinations. To further explore this association, we administered a four-tone, auditory oddball task to people with schizophrenia (PSZ, n = 69), people with bipolar disorder (PBD, n = 34), first degree relatives of people with schizophrenia (SREL, n = 54 ) and healthy controls (CON, n = 80). A sequential pair of tones were presented to each ear with participants indicating when they heard target tones. Participants allocated attention to either their left or right ear while ignoring tones in the opposite ear. Behaviorally, both patient groups exhibited less ability to discriminate between target and non-target tones (signal detection measure d’) compared to CON. Furthermore, PSZ alone exhibited a more conservative response bias (signal detection measure C) compared to other groups. Finally, delayed correct reaction times to target tones by both PSZ and PBD compared to CON confirmed the presence of inefficient perceptual discrimination and decision-making related to the auditory stimuli. To better understand these findings, we will analyze simultaneously collected EEG data. We expect weakened perceptual suppression to distractor tones in PSZ as indexed by a lack of inhibitory alpha band activity.