Stumbling on Happiness

Gilbert, a Harvard psychologist, argues that people are systematically bad at predicting what will make them happy, and explains the specific mechanisms that produce the error. The book is about prospection, meaning the mental simulation of future experiences, rather than about happiness itself.

His argument has three parts. Imagination fills in details that are not there, so a simulated future contains invented specifics the person treats as given. Imagination leaves out details that will be there, particularly the ordinary context surrounding any imagined event, which is why people imagine a promotion or a move without imagining the daily conditions around it. And imagination fails to account for how the mind will reinterpret events once they occur, which Gilbert calls the psychological immune system.

The evidence includes work on affective forecasting showing that people overestimate both the intensity and the duration of their emotional responses to events, both positive and negative. Lottery winners and people who become paraplegic converge toward their prior baseline faster than anyone predicts. He also covers the finding that people rationalise outcomes they cannot change, which means the events people most fear are frequently ones they would adapt to.

His practical recommendation is surrogation, meaning asking people who are currently in the situation you are considering how they feel, which he shows outperforms imagining it yourself. He notes that people reject this advice because they believe they are unique. Some of the studies have replicated poorly, particularly in the affective forecasting literature where effect sizes are smaller than reported. Gilbert's writing style is heavily comic and some readers find it wearing. The core finding about impact bias holds.