Economists have spent decades modelling nostalgia as a quantity. It behaves more like a weather system. The usual story is that we are careless calculators. The better story is that we are careful about the wrong things. In the studies we have, the effect is modest, reliable and almost entirely ignored by the people it describes. The evidence here is thinner than the confident commentary suggests, and the honest position is a shrug with a direction of travel.
Three kinds of mistake
What looks like nostalgia from the outside is usually something simpler from the inside: tiredness, a deadline, a wish not to look foolish. Consider the tip jar. It is a small thing, and small things are where habits live. The textbook treats nostalgia as a preference to be revealed. In practice it is a story we tell ourselves after the fact. A better account of nostalgia would begin with the ordinary case rather than the laboratory one.
