INVESTIGATING THE PERCEPTION OF SIMULTANEITY IN PSYCHOSIS: A COMPARISON OF FIRST-EPISODE PSYCHOSIS AND TREATMENT-RESISTANT SCHIZOPHRENIA PATIENTS WITH HEALTHY CONTROLS

  • Heike Schmidt
  • John McFarland
  • Mohamed Ahmed
  • Colm McDonald
  • Mark A. Elliott

Abstract

In order to investigate whether difficulties with temporal event-coding, previously reported inpatients with schizophrenia, are already present during first-episode psychosis (FEP) or ifthey develop gradually over time, the subjective judgments of the simultaneity of visuallypresented stimuli were compared between 46 healthy controls, 29 treatment-resistantschizophrenia (TRSZ) patients with schizophrenia and 29 FEP patients. Participantsunderwent two experiments, where they were asked to indicate whether two vertical barsappeared simultaneously or at different times on the screen. The results of both experimentssuggest that particularly TRSZ patients required longer intervals between stimulus onsetsthan did controls to detect the asynchrony. Both patient groups showed much higher elevatedthresholds when the range of SOAs used were increased, which might reflect differences insymptomology. Particularly TRSZ patients appear to experience difficulties with judgingsimultaneity. FEP patients also appear to have slight impairments but the extent of theseimpairments is less pronounced than in the TRSZ sample.
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