Research Report Impaired strategic decision making in schizophrenia Hyojin Kim a , Daeyeol Lee b , Young-Min Shin c , Jeanyung Chey a, ⁎ a Department of Psychology, Seoul National University, San 56-1 Shillim-dong Kwanak-gu, Seoul 151-742, Republic of Korea b Department of Neurobiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA c Department of Psychiatry, Seoul Medical Center, 171-1 Samsung-dong Kangnam-gu, Seoul 135-740, Republic of Korea ARTICLE INFO ABSTRACT Article history: Accepted 22 August 2007 Available online 28 August 2007 Adaptive decision making in dynamic social settings requires frequent re-evaluation of choice outcomes and revision of strategies. This requires an array of multiple cognitive abilities, such as working memory and response inhibition. Thus, the disruption of such abilities in schizophrenia can have significant implications for social dysfunctions in affected patients. In the present study, 20 schizophrenia patients and 20 control subjects completed two computerized binary decision-making tasks. In the first task, the participants played a competitive zero-sum game against a computer in which the predictable choice behavior was penalized and the optimal strategy was to choose the two targets stochastically. In the second task, the expected payoffs of the two targets were fixed and unaffected by the subject's choices, so the optimal strategy was to choose the target with the higher expected payoff exclusively. The schizophrenia patients earned significantly less money during the first task, even though their overall choice probabilities were not significantly different from the control subjects. This was mostly because patients were impaired in integrating the outcomes of their previous choices appropriately in order to maintain the optimal strategy. During the second task, the choices of patients and control subjects displayed more similar patterns. This study elucidated the specific components in strategic decision making that are impaired in schizophrenia. The deficit, which can be characterized as strategic stiffness, may have implications for the poor social adjustment in schizophrenia patients. © 2007 Elsevier B.V. All rights reserved. Keywords: Decision making Game theory Mixed strategy Random response Prefrontal cortex Social dysfunction Executive function 1. Introduction Schizophrenia is a debilitating disorder characterized by a variety of cognitive impairments and poor social functioning, which often result in a decline in the socioeconomic status of the patients suffering the illness (American Psychiatric Asso- ciation, 1994; Carson, 1984; Hollingshead and Redlich, 1958). In particular, the process of adaptive decision making might be impaired in schizophrenia (Ernst and Paulus, 2005; Ludewig et al., 2003; Ritter et al., 2004; Shurman et al., 2005; Waltz and Gold, 2007). During the process of decision making, the pros and cons of available options are evaluated, and a particular option is selected, often in the context of uncertainty (Tversky and Kahneman, 1981). This is necessary for everyday tasks ranging from making personal choices of grooming to main- taining interpersonal relationships and meeting occupational responsibilities. Two related lines of evidence suggest that schizophrenia patients may be impaired in their ability to BRAIN RESEARCH 1180 (2007) 90 – 100 ⁎ Corresponding author. Fax: +82 2 880 6428. E-mail address: jychey@snu.ac.kr (Jeanyung Chey). 0006-8993/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.brainres.2007.08.049 available at www.sciencedirect.com www.elsevier.com/locate/brainres