Are Probabilities Overweighted or Underweighted When Rare Outcomes Are Experienced (Rarely)?
Are Probabilities Overweighted or Underweighted When Rare Outcomes Are Experienced (Rarely)?
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DOI：
10.1111/j.1467-9280.2009.02319.x
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发表时间：
2009-04
影响因子：
8.2
通讯作者：
Christoph Ungemach;N. Chater;Neil Stewart
中科院分区：
文献类型：
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作者：
Christoph Ungemach;N. Chater;Neil Stewart
当根据结果及其相关概率的口头描述做出涉及风险结果的决策时，人们的行为就好像他们过度重视小概率一样。相反，当在一系列样本中经历相同的结果时，人们的行为就好像他们低估了小概率。我们提出的两个实验表明，现有的对经验决策中观察到的权重不足的解释不足以解释这种影响。当参与者经历代表性事件样本时，观察到权重不足，因此不能归因于小概率的抽样不足。此外，早期样本预测决策的能力与后来样本的预测能力一样，因此权重不足不能归因于近期权重。最后，频率判断是准确的，因此不能将权重过低归咎于判断错误。此外，我们表明，当前景理论（风险选择的主导模型）应用于数据时，小概率的权重不足也反映在获得的最佳拟合参数值中。
When making decisions involving risky outcomes on the basis of verbal descriptions of the outcomes and their associated probabilities, people behave as if they overweight small probabilities. In contrast, when the same outcomes are instead experienced in a series of samples, people behave as if they underweight small probabilities. We present two experiments showing that the existing explanations of the underweighting observed in decisions from experience are not sufficient to account for the effect. Underweighting was observed when participants experienced representative samples of events, so it cannot be attributed to undersampling of the small probabilities. In addition, earlier samples predicted decisions just as well as later samples did, so underweighting cannot be attributed to recency weighting. Finally, frequency judgments were accurate, so underweighting cannot be attributed to judgment error. Furthermore, we show that the underweighting of small probabilities is also reflected in the best-fitting parameter values obtained when prospect theory, the dominant model of risky choice, is applied to the data.