One finding that emerges consistently from social psychology is this: some people are just really strange. In 1966, experimenters went door to door in a suburban neighbourhood, asking residents if they'd agree to have an enormous billboard reading "Drive Carefully" erected in their front gardens, for nothing in return. To give an idea of how it would look, they were shown a photograph of a lovely home almost completely hidden by a huge, ugly sign. Astonishingly, 17% said yes.
Why? No idea, and frankly they were probably beyond help to begin with. But the more interesting result concerned a subgroup of residents who'd agreed, two weeks earlier, to display a three-inch-square notice saying "Be A Safe Driver": 76% of them agreed to the billboard.
I suppose I can live with the idea that 17% of people are such pushovers that they'd let a hoarding destroy their living environment just because someone with a clipboard asked them. Then again, like most people, I'd probably have agreed to the three-inch notice: I like to think I'm public-spirited. But once I'd done that, this experiment implies, it's likely I'd have said yes to the billboard, just like the oddballs. So am I an oddball, too? That's a rhetorical question; I'm not soliciting answers.
The phenomenon at work is the marketing trick known as "incremental commitment", described by Robert Cialdini in his endlessly entertaining book Influence, a guide to the dark arts of "compliance professionals" (telemarketers, charity muggers, prisoner of war camp guards - you know the type). We value consistency above almost anything and will go to extremes to maintain it. Partly, this is a matter of keeping up appearances: if you've presented yourself as committed to road safety, you may fear, albeit subconsciously, giving a contradictory impression. But it's more profound than that: once you've made a commitment, even a small one, you want to believe, deep down, that it was right. So you'll alter your actions and feelings in the direction of that conclusion. You'll genuinely want that billboard.
Another example: studies suggest that after placing a bet on a horse, most people are more confident than before about its prospects. What's changed is that they've invested - financially, but also psychologically, since a victory for the horse would be consistent with the decision to make the bet.
For Cialdini, this is a problem: he's worried we might act contrary to how we "really" feel merely to seem consistent to ourselves or others. (You date someone, so you move in together, marry, have children... only to discover you're miserable, because you were pursuing each step to justify the last.) But the feelings that emerge in us to preserve consistency can be, he acknowledges, entirely real. And far from being a problem, that leads to a conclusion that's strangely freeing - especially if you're fretting over some major life decision, worried about making the right choice. The consistency principle implies that whatever you choose, you're predisposed to come to feel that you chose correctly. That massive billboard in my front garden, by the way? Best decision I ever made.