In 1998, Kahneman tested whether California brings happiness

Today, the rule fits in three lines: before signing a lease in another city because of the weather, the beach or the views, work out how much of the week you will actually spend looking at those things. Under 20 hours: it is not a life change.

2011: Schkade and Kahneman repeat the test with marriage, cars and salaries. The illusion holds. The perceived weight of change is always greater than its actual weight in daily life.

2002: Daniel Kahneman wins the Nobel in Economics for explaining this kind of bias, much of it published with Amos Tversky.

1998: at the University of California San Diego and at Princeton, David Schkade and Daniel Kahneman ask 3,043 students from the Midwest and from Southern California about their life satisfaction. Beforehand they ask them to guess who would be happier: both groups agree without hesitation that the Californians would. It turns out no. The average lands at 5.8 versus 5.7 out of 10, essentially a tie. Climate ranks sixteenth in the list of drivers of well-being; only health and money move the needle in any clear way.

The authors called this the focusing illusion: when you think about one concrete thing —that city, that job, that body—, you inflate its weight. The beach is thirty minutes away and you use it three hours a month; the job is forty hours a week.