Why Do Defaults Affect Behavior? Experimental Evidence from Afghanistan
通过随机分配员工到不同工资关联储蓄账户，发现默认注册使参与率提高40个百分点，效果相当于50%的匹配激励；进一步实验表明，默认效应主要由现时偏好和思考不同储蓄情景的认知成本驱动。
We report on an experiment examining why default options impact behavior. By randomly assigning employees to different varieties of a salary-linked savings account, we find that default enrollment increases participation by 40 percentage points—an effect equivalent to providing a 50 percent matching incentive. We then use a series of experimental interventions to differentiate between explanations for the default effect, which we conclude is driven largely by present-biased preferences and the cognitive cost of thinking through different savings scenarios. Default assignment also changes employees’ attitudes toward saving, and makes them more likely to actively decide to save after the study concludes.