The evidence is real and the argument about it is still running: how strong it is, how far it travels, or whether it repeats. Trust the direction, and hold the numbers loosely.
Assistant professors were asked to predict how unhappy they would be if they were denied tenure, the verdict that shapes an academic career. They forecast lasting damage. Then the researchers found people who actually had been denied tenure years earlier and measured them. They were about as happy as the ones who got it. Gilbert and Wilson traced the miss to two mechanisms. Focalism: when you imagine an event, you stare straight at it and forget that ordinary life, work, family, weather, keeps running and keeps claiming your attention. And immune neglect: everyone owns a psychological immune system that rationalises, reframes, and makes sense of what happens, and nobody budgets for it in the forecast. One later experiment made the miss physical. People choosing a dose of a mood-repair drug before a romantic rejection picked twice the dose that people who had just actually been rejected chose. The forecast of the blow was double the blow.
Big decisions ride on these forecasts. People stay in wrong jobs because they overprice the pain of leaving, and chase titles because they overprice the joy of arriving. The bias inflates both tails, so you overpay for wins and overinsure against losses. Two working corrections. Stop simulating and start sampling: find someone who actually lives inside the outcome you are imagining and ask what an ordinary Tuesday feels like, because their report beats your imagination. And widen the frame on purpose: list what else will fill the weeks after the event, since that is exactly what focalism deletes. The honest limit is the dispute itself. The critics showed that when you ask people how they will feel about the event specifically, immediately afterwards, forecasts are fairly accurate. The reliable miss is about your life overall and about how long the feeling lasts. Which happens to be the version that matters for decisions, because nobody quits a job over how they will feel for one hour.
The overview paper is Wilson and Gilbert, Affective Forecasting, in Advances in Experimental Social Psychology, 2003. The dispute runs through Levine, Lench, Kaplan and Safer in 2012, a reply from Wilson and Gilbert titled The Impact Bias Is Alive and Well in 2013, and a counter-reply from Levine and colleagues in the same year arguing the bias is both dead and alive.
The hot-cold empathy gap says the calm version of you cannot predict what the excited version will do, so rules written cold get broken hot by the same people who wrote them. Affective forecasting says you overestimate how strongly and how long a future event will make you feel, so you stay in the wrong job because you overprice the pain of leaving. Both are you mispredicting a future version of yourself, in opposite directions. Hot-cold underestimates the pull of the moment. Forecasting overestimates the weight of what comes after. One is about what you will do; the other is about how you will feel. The fixes differ accordingly: leave something behind that the hot version has to walk past, and ask someone already living inside the outcome what an ordinary Tuesday feels like.
Implementation intentions say that tying an action to a concrete cue, if this then that, raises follow-through by a medium-to-large margin across 94 studies. Affective forecasting says the goal you are committing to may rest on a misprediction of how the outcome will feel. So the pre-commitment that makes you act may be locking in a forecast that was wrong. The intentions entry is honest about this on its own: the plan spends motivation rather than creating it, and if you do not actually want the goal, naming Tuesday changes nothing. What separates them is which failure you are in. If the problem is starting, intentions are the lever. If the problem is that the goal was chosen by imagination rather than by sampling, an if-then plan just gets you there faster.
Daniel Gilbert, 2006
Gilbert's book-length account of the affective forecasting work, and the source of the sampling advice: other people's experience predicts your future feelings better than your own imagination does.
Draw your own card. It does not take long, and it rewards taking your time.