Do watching eyes affect charitable giving? Evidence from a field experiment
通过在瑞典超市的回收机上张贴眼睛图片，研究观察线索对慈善捐赠的影响，发现仅在客流量少时捐赠增加30%。
Abstract The presence of implicit observation cues, such as picture of eyes, has been shown to increase generosity in dictator games, and cooperative behavior in field settings. I combine these approaches, by testing if a picture of watching eyes affects unconditional giving in a natural environment, where the recipient is a charity organization. Taken together, this study reduces the influence of three potential confounding factors in previous experiments: (i) experimenter demand effects, (ii) that the facial cue reminds subjects of a human counterpart, and (iii) a social multiplier effect. Specifically, the paper reports results from an experiment, conducted in a Swedish supermarket chain, where customers face a naturally occurring decision problem. People who recycle cans and bottles have to choose whether to keep the recycled amount or donate it to a charity organization. By posting a picture of human eyes on recycling machines, I am able to test whether this causes an increase in donations to the charity. Based on a sample covering a 12-day period, 38 stores and 16775 individual choices, I find no general effect. However, when controlling for store and day fixed effects, and using a proxy for store attendance, the picture of eyes increased donated amount by 30 percent during days when relatively few other people visited the store. This result gives further support to the conclusion that subtle social cues can invoke reputation concerns in humans, although the relatively small effect suggests that previous estimates could be biased upward, or at least that the influence of observational cues is context dependent.