Inukai Keigo, Takahashi Taiki
Department of Behavioral Science, Hokkaido University, Sapporo 060-0810, Japan.
Med Hypotheses. 2006;67(2):283-6. doi: 10.1016/j.mehy.2006.02.014. Epub 2006 Mar 30.
Decision-making under uncertainty has been studied in psychiatry, economic psychology, and neuroeconomics. Psychiatric patients (e.g., drug addicts) often show low degrees of aversion to potential danger. Investigation into neuropsychological processing underlying decision under uncertainty is important for medical treatments of neuropsychiatric disorders. In economic decision theory, choices under uncertainty with and without known probabilities of outcomes have been discriminated. Regarding decision-making under uncertainty with known probabilities (risk), Kahnemann-Tversky's prospect theory revealed that people tend to avoid uncertainty in potential gains (i.e., risk-aversion in a gain-frame); on the contrary, prefer uncertainty in potential losses (i.e., risk-seeking in a loss-frame). Regarding choices between possible gains with known and unknown probabilities, Ellsberg demonstrated that, in a gain-frame, people tend to avoid uncertainty with unknown probabilities, more dramatically than uncertainty with known probabilities. This can be explained by risk/uncertainty aversion in the gain-frame, suggesting that uncertainty with known and unknown probabilities (i.e., risk and Knightian uncertainty, respectively) may possibly be processed by similar neuropsychological processing in the gain-frame. However, in spite of accumulating evidence in neuroimaging and neuroeconomic studies, it is still unknown whether probability and Knightian uncertainty in the loss-frame are mediated by similar neuropsychological processes as well. We propose that distinct neuropsychological processes may mediate potential losses with known and unknown probabilities, based on recent findings in neuroeconomics and our experiment. Importance of examining subjects' degree of Knightian uncertainty aversion for the prediction/treatment of drug addicts' risky behavior (e.g., needle-sharing) is also discussed.
不确定性下的决策已在精神病学、经济心理学和神经经济学中得到研究。精神病患者（如吸毒者）往往对潜在危险的厌恶程度较低。探究不确定性下决策背后的神经心理过程对于神经精神疾病的医学治疗至关重要。在经济决策理论中，已区分了在有和没有已知结果概率情况下的不确定性选择。关于已知概率（风险）下的不确定性决策，卡尼曼 - 特沃斯基的前景理论表明，人们倾向于避免潜在收益中的不确定性（即在收益框架下的风险厌恶）；相反，在潜在损失中更喜欢不确定性（即在损失框架下的风险寻求）。关于在已知和未知概率的可能收益之间的选择，埃尔斯伯格表明，在收益框架下，人们倾向于避免未知概率的不确定性，比避免已知概率的不确定性更为显著。这可以用收益框架下的风险/不确定性厌恶来解释，表明已知和未知概率的不确定性（即分别为风险和奈特不确定性）在收益框架下可能由相似的神经心理过程处理。然而，尽管神经影像学和神经经济学研究证据不断积累，但损失框架下的概率和奈特不确定性是否也由相似的神经心理过程介导仍不清楚。基于神经经济学的最新发现和我们的实验，我们提出不同的神经心理过程可能介导已知和未知概率的潜在损失。还讨论了检查受试者奈特不确定性厌恶程度对于预测/治疗吸毒者危险行为（如共用针头）的重要性。
