Human behavior tends to change based whether or not someone else is watching - just ask any dog owner with a pocket full of plastic bags who still leaves a steaming pile of poop in an unpopulated park.
But what if those watchful eyes are obviously fake?
Doesn't make a difference. Studies have shown that simply tacking up posters of watchful eyes decreases bike theft, increases the amount of money put in break-room honor boxes where employees plunk money for donuts and coffee, and encourages people to clean up after themselves in cafeterias.
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And it doesn't seem to matter where those eyes appear, suggests new research. When eyes were printed on a really-tempting-to-discard objects - like the promotional leaflets handed out on street corners - littering dropped by two-thirds.
The study also found that - in a shock to absolutely no one - littering went down when other people were nearby.
"In the fight against anti-social littering, this study could be a real help. Fast food retailers might want to think about using it on packaging to discourage people discarding the wrappers," study author Melissa Bateson, a professor at the Center for Behavior and Evolution at Newcastle University, said in a release.
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"The flip side is, for those handing out leaflets, it could help people take in the messages are they are less likely to throw away a flyer with eyes on."
While there's no way to attach eyes to dog poop (though Christopher Walken's plants might disagree), the study highlights the sometimes big divide between what humans do when they're being observed - or at least think they are - and when they're not.
For the litter-prone among us, it also harkens the timeless wisdom of Thomas Jefferson in a 1785 letter to Peter Carr:
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"Whenever you are to do a thing, though it can never be known but to yourself, ask yourself how you would act were all the world looking at you, and act accordingly."