| Project/Area Number |
15530444
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Clinical psychology
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| Research Institution | University of Tokyo |
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Principal Investigator |
TANNO Yoshihiko University of Tokyo, Graduate School of Arts and Sciences, Associate Professor, 大学院・総合文化研究科, 助教授 (60179926)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAYASU Nobuo University of Tokyo, Graduate School of Medicine, Associate Professor, 大学院・医学系研究科, 助教授 (70126134)
ISHIGAKI Takuma University of Tokyo, Graduate School of Arts and Sciences, Associate Professor, 大学院・総合文化研究科, 助教授 (70323920)
OHMORI Takuya Tama University, Faculty of Business Information, Associate Professor, 経営情報学部, 助教授 (80332617)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Delusional Ideation / Schizophrenia / Bayesian analysis / 心の理論 |
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| Research Abstract |
The present study examined the two major hypotheses on the pathogenesis of delusional ideation, a) jumping to conclusion bias and b) causal attribution bias.
Deluded schizophrenic patients were found to request less information before reaching a decision and to express higher certainty levels than the control groups. This reasoning bias was called jumping to conclusion bias from the point of view of Bayesian statistics. In the present study, jumping to conclusion bias in delusion-prone college students and schizophrenic patients were examined by the probabilistic judgmental task. Schizophrenic patients and normal college students participate in the studies. Normal college students were divided into the high delusional students and low delusional students using the Peters Delusional Inventory. In the probabilistic judgmental tasks, participants were asked whether they required more draws before they came to a decision. After each draw, participants indicated the relative probabilities that they attached to the draw having come from each of the two jars. The schizophrenic patients group drew significantly less than control group. The delusion-prone college students group reached significantly higher initial posterior estimate than the schizophrenic patients group and the control group. The delusion-prone college students group reached higher certainty after tenth beads than the schizophrenic patients group. These results were consistent with the previous studies.
In another studies using tasks of causal attributions, the delusion-prone college students group made more internal attribution on the positive events, whereas they made more external attribution on the negative events. These causal attribution bias can explain the pathogenesis of delusional ideation. Internal attribution on the positive events can explain the delusion of grandiose, whereas external attribution on the negative events can explain the delusion of persecution.
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