I remember a study about how a picture of an eye made people more well behaved. The experiment was in an unsupervised coffee room where there was a box where participants were expected to deposit money after getting their coffee. However, due to lack of supervision, the participants had the option of leaving no money in the box and getting a free coffee. The study had two conditions, when a picture of a plant hung over the coffee maker and a picture of an eye. They found that participants contributed more money in the eye condition.

What is the original reference and name of this study? What mechanisms did the authors propose to explain this effect? Have the results been replicated in similar studies? How does the increase in contribution compare to cases with passive surveillance like an easily visible camera in the room (but not eye shaped)?

  • $\begingroup$ This is fascinating! Very interesting effect. $\endgroup$
    – Josh
    May 18, 2013 at 17:53

1 Answer 1


A study that used the field setting you describe is done by Bateson et al. (2006).

As for the mechanism, they write:

we believe that images of eyes motivate cooperative behaviour because they induce a perception in participants of being watched. Although participants were not actually observed in either of our experimental conditions, the human perceptual system contains neurons that respond selectively to stimuli involving faces and eyes (Emery 2000; Haxby et al. 2000), and it is therefore possible that the images exerted an automatic and unconscious effect on the participants’ perception that they were being watched. Our results therefore support the hypothesis that reputational concerns may be extremely powerful in motivating cooperative behaviour.

Similar findings have been found in a lab setting by Haley and Fessler (2005). They also compared the effect to other cues (such as auditory cues) of presence of others and found similar effect. So I don't have a direct answer to the surveillance camera scenario, but these results suggest the effect would be similar.

However, it is clear that this effect depends on many variables. For example, it has been shown not exist in darkness (Tane and Takezawa, 2011), and to depend on culture (Raihani and Bshary, 2012).


  • Bateson, M., Nettle, D., & Roberts, G. (2006). Cues of being watched enhance cooperation in a real-world setting. Biology letters, 2(3), 412-414.
  • Haley, K. J., & Fessler, D. M. (2005). Nobody's watching?: Subtle cues affect generosity in an anonymous economic game. Evolution and Human behavior, 26(3), 245-256.
  • Tane, K., & Takezawa, M. (2011). Perception of human face does not induce cooperation in darkness. Letters on Evolutionary Behavioral Science, 2(2), 24-27.
  • Raihani, N. J., & Bshary, R. (2012). A positive effect of flowers rather than eye images in a large-scale, cross-cultural dictator game. Proceedings of the Royal Society B: Biological Sciences, 279(1742), 3556-3564.

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