Wu Shih-Wei, Delgado Mauricio R, Maloney Laurence T
Division of the Humanities and Social Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
Proc Natl Acad Sci U S A. 2009 Apr 14;106(15):6088-93. doi: 10.1073/pnas.0900102106. Epub 2009 Mar 30.
There is considerable evidence that human economic decision-making deviates from the predictions of expected utility theory (EUT) and that human performance conforms to EUT in many perceptual and motor decision tasks. It is possible that these results reflect a real difference in decision-making in the 2 domains but it is also possible that the observed discrepancy simply reflects typical differences in experimental design. We developed a motor task that is mathematically equivalent to choosing between lotteries and used it to compare how the same subject chose between classical economic lotteries and the same lotteries presented in equivalent motor form. In experiment 1, we found that subjects are more risk seeking in deciding between motor lotteries. In experiment 2, we used cumulative prospect theory to model choice and separately estimated the probability weighting functions and the value functions for each subject carrying out each task. We found no patterned differences in how subjects represented outcome value in the motor and the classical tasks. However, the probability weighting functions for motor and classical tasks were markedly and significantly different. Those for the classical task showed a typical tendency to overweight small probabilities and underweight large probabilities, and those for the motor task showed the opposite pattern of probability distortion. This outcome also accounts for the increased risk-seeking observed in the motor tasks of experiment 1. We conclude that the same subject distorts probability, but not value, differently in making identical decisions in motor and classical form.
有大量证据表明，人类经济决策偏离了预期效用理论（EUT）的预测，而人类在许多感知和运动决策任务中的表现符合EUT。这些结果可能反映了这两个领域决策的实际差异，但观察到的差异也可能仅仅反映了实验设计中的典型差异。我们开发了一种在数学上等同于在彩票之间进行选择的运动任务，并使用它来比较同一受试者在经典经济彩票和以等效运动形式呈现的相同彩票之间的选择方式。在实验1中，我们发现受试者在决定运动彩票时更倾向于冒险。在实验2中，我们使用累积前景理论对选择进行建模，并分别估计每个执行每项任务的受试者的概率加权函数和价值函数。我们发现受试者在运动任务和经典任务中对结果价值的表征没有模式化差异。然而，运动任务和经典任务的概率加权函数明显且显著不同。经典任务的概率加权函数表现出典型的倾向，即高估小概率并低估大概率，而运动任务的概率加权函数则表现出相反的概率扭曲模式。这一结果也解释了在实验1的运动任务中观察到的冒险增加现象。我们得出结论，同一受试者在以运动形式和经典形式做出相同决策时，对概率的扭曲不同，但对价值的扭曲相同。
