Archival ReportNegative Symptoms of Schizophrenia Are Associated with Abnormal Effort-Cost Computations
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Participants
Forty-four individuals (42 outpatients, 2 inpatients) meeting DSM-IV (27) criteria for SZ (n = 36) or schizoaffective disorder (n = 8, none in mood episode at time of testing) and 36 healthy control subjects (CN) participated in the study. Patient and control groups did not significantly differ on age, parental education, gender, or ethnicity (Table 1). All patients were taking stable doses of medication for at least 4 weeks at the time of testing and were considered to be clinically stable by
Selection of Effortful Alternative in Relation to Value
Panels A and B of Figure 2 present the proportion of effortful response alternative selections as a function of potential gain value ($3–$7). A 2 Group (SZ vs. CN)×2 Probability (50% vs. 100%)×5 Value ($3, $4, $5, $6, $7) repeated-measures analysis of variance (ANOVA) indicated significant within-subjects effects of probability [F1,78 = 120.6, p<.01] and value [F4,78 = 61.90, p<.001]. However, the between-subjects effect was nonsignificant [F1,78 = 1.12, p = .29]. These analyses indicate that,
Discussion
These data suggest that negative symptoms are associated with abnormalities in effort-cost calculations. Patients with higher levels of negative symptoms were less willing to increase effort for higher levels of reward and were also less responsive to the receipt of an uncertain reward in motivating subsequent effortful behavior. This alteration in decision making was accompanied by more general evidence of reduced behavioral activation as seen in decreased response vigor in both high- and
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