People don't act rationally. One way to tell this is from studies of behavioural economics (the sort of studies made famous by Dan Ariely). Typically, these studies require some sort of anonymous dealings.
People usually don't cheat as much in these studies as they could. Since the rational thing to do in such a situation is to cheat all you can (since no-one will ever find out), it follows that people aren't rational.
Take, for example, the studies of Richard Sosis on Israeli Kibbutz members. They measured how much these Kibbutzim would contribute to a common pot in an anonymous game.
The rational amount to contribute is zero. Of course people do contribute, but what Sosis found was that those members who attended public rituals more often contributed more.
In other words, participating in these public rituals made them more irrational, in favour of the group and against their own narrow self interest. That's a good thing for the group, of course.
Now, public rituals are a classic 'costly signal'. They show that you are committed to being a member of the group (for whatever reason) - because there's no other reason to do them. But that doesn't explain why more committed group members contribute more.
One possibility is that they don't believe the experiment is truly anonymous. This is a problem for all studies like this. Another is that it's something to do with religion (perhaps these people think their God is watching them).
But I want to suggest an alternative, altogether weirder explanation. And to do that, we need to talk about why people vote. Voting is, of course, completely irrational. You know that your one vote will never make a difference. And yet people do it in their millions.
If you read a recent post at the ever-excellent Psyblog, you'll know that there's a kind of magical thinking at work here. We vote because we think that the act of voting will actually influence other people to vote the same way (even though we know it's totally anonymous).
The evidence for this comes from work done by George Quattrone and Amos Tversky back in the 1980s - you can read a summary of their study here.
Could it be that the Kibbutzim who are more committed to the group (as signalled by taking part in public rituals) are actually more generous because they are trying to get other group members to do the same?
If so, then this explains their irrational behaviour. They may well believe that the experiment is truly anonymous, but they just can't help acting as if it isn't.
4 hours ago in The Phytophactor