Kahneman and Tversky Flipped a Coin to Decide Whose Name Went First on Their Papers

Daniel Kahneman and Amos Tversky met in 1968 in the psychology department at Hebrew University in Jerusalem. They were complementary in the way collaborators sometimes are — Kahneman, the older one, deliberate and given to second-guessing; Tversky, faster and more confident — and the partnership became the engine for what is now called behavioral economics. Their first joint paper appeared in 1971. They flipped a coin to decide whose name went first; afterward they alternated. They later said they had been "inseparable" and "soul mates," which is unusual language for academic acknowledgments and accurate to the work.

The defining product of the partnership is prospect theory, drafted starting in 1972 and finally published in Econometrica in 1979 after more than three years of revisions. The paper rebuilt the standard economic model of choice under uncertainty — expected-utility theory, in which agents weight outcomes by their probabilities — into something that fits how humans actually choose. People weight losses about twice as heavily as equivalent gains. They evaluate outcomes against a reference point rather than against absolute wealth. They distort probabilities, especially small ones. The paper became, by several measures, the most-cited article in economics.

Kahneman and Tversky drifted apart professionally after Kahneman moved to Berkeley in 1978. The collaboration tapered through the 1980s but did not end. Tversky died of metastatic melanoma in 1996, at 59, three years before the Nobel committee began seriously considering the work. Kahneman accepted the 2002 Nobel Memorial Prize in Economic Sciences alone. "Our collaboration on judgment and decision making," he wrote in Thinking, Fast and Slow in 2011, "was the reason for the Nobel Prize that I received in 2002, which Amos Tversky would have shared had he not died."