In the studies we have, the effect is modest, reliable and almost entirely ignored by the people it describes. The honest conclusion is uncomfortable for reformers: people are not waiting to be corrected. Economists have spent decades modelling habit as a quantity. It behaves more like a weather system. The mind that evolved for small groups and immediate dangers is now asked to manage a pension. It does its best.
Three kinds of mistake
The usual story is that we are careless calculators. The better story is that we are careful about the wrong things. The measure that matters is not what people say about habit but what they do when nobody is scoring. The remedy is rarely exhortation. It is a change to the situation so that the easier choice is also the better one. A better account of habit would begin with the ordinary case rather than the laboratory one.
A pattern this consistent is not a character flaw. It is a design feature, and design features can be worked with. There is a version of this essay that ends with a policy prescription. This is not that version; the mechanism is interesting enough on its own. Consider the polite refusal. It is a small thing, and small things are where habits live. A better account of habit would begin with the ordinary case rather than the laboratory one.
