Participants

Twenty-four patients with schizophrenia were recruited and were assessed for Axis I²⁵ and II²⁶ disorders based on the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (SCID). Their psychiatric symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS).²⁷ No patient had a lifetime history of central nervous system disease, alcohol or drug abuse, electroconvulsive therapy, mental retardation, or head injury with loss of consciousness. All patients were receiving atypical antipsychotic medication at the time of testing (risperidone, n=15; olanzapine, n=7; and quetiapine, n=2).

Twenty-three HCs were recruited from the local community through newspapers and flyers. An initial screening interview excluded subjects with any identifiable neurological disorder or head injury or any personal or family history of psychiatric illness. After the initial screening, potential HCs were interviewed using the SCID for Axis II Psychiatric Disorders²⁶ and were excluded if they had any of these disorders.

All subjects had normal or corrected-to-normal vision and were right-handed, as determined by asking about the hand used for writing and other precise motor skills. All subjects signed a written informed consent form approved by the Institutional Review Board of Inje University Ilsan Paik Hospital.