Sometimes, it only takes the slightest hint to make us act ethically, or at least not unethically.
Even before the first animals, life forms sought ways to get others to place the common good above personal gain. Even in communities of single-celled organisms, some seek a free ride on the majority who produce defensive molecules and need to be brought into line.
Examiners need to stop their students cheating on tests, but sometimes methods that make this impossible are too difficult or expensive. However, obstacles that make cheating more difficult, such as cardboard partitions that prevent one student from stealing a glance at their neighbor's answers, usually work pretty well.
This raises the question, however, of whether such obstacles work because of the difficulties they create or because they remind people cheating is socially unacceptable. Professor Gail Heyman of the University of California, San Diego, sought an answer by replacing the cardboard with transparent plastic and even empty metal frames.
In Proceedings of the National Academy Of Sciences, Heyman and co-authors report on a study of 350 children aged 5-6. The children were given a test with the last question far beyond their age bracket. The answers were open on a desk next to them, but an instructor told the children not to look before leaving the room.
With no barrier, more than half the children cheated, but this dropped to 28 percent among those with the empty frame and just 16 percent with the transparent plastic between them and the answers.
A “frame” outlined in the air by the experimenter with a “magic wand” also proved effective.

“Our work... suggests that people's ideas about morality are deeply rooted in how they think about space. This is probably why there are so many spatial metaphors for morality such as 'cross the line' and 'keep on the straight and narrow,'" Heyman said in a statement.
The clear dividers represent what psychologists call a “nudge”, something that induces socially desirable behavior without coercion. Enforcement of laws can be expensive and sometimes sweeps up people who have a good reason not to follow the rules. Nudges, where effective, are often much better. If we could nudge most people into wearing masks in public, for example, it might induce less resistance than mandates enforced with fines and not hit hardest those with the least ability to pay.
The paper is part of an expanding field of investigations into what sort of nudges work and under what circumstances. The paper provides examples of having adults write down moral codes or making children promise to be honest as past examples that have shown some effectiveness, but the authors consider their own test more subtle.
However, the study also carried some bad news. Older children (even by a few months) were more likely to cheat, although the transparent barriers remained roughly as effective with age.