Amos Tversky

• 1. Introduction

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  Amos Nathan Tversky was born on the 16th of March 1937 in Haifa, British Palestine, and by the time he died in 1996, he had helped overturn one of the most confident assumptions in modern economics: that human beings, when making decisions, behave rationally. He never won a Nobel Prize. He died before one could be awarded. But six years after his death, his longtime collaborator Daniel Kahneman accepted the 2002 Nobel Memorial Prize in Economic Sciences and made clear that the work was shared. Kahneman would later say, "it is a joint prize. We were twinned for more than a decade." How does a psychologist from Haifa end up reshaping the foundations of economic theory? And who, exactly, was the man his colleagues judged so brilliant that they devised an informal test in his name? Those are the questions this documentary will answer.

• 2. Haifa to Harvard, the Early Years

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  Jenia Tversky, Amos's mother, was a Lithuanian Jewish social worker who eventually became a member of the Israeli Knesset representing the Mapai, the Workers' Party. His father, Yosef, was a Polish-born veterinarian. Amos was the younger of two children, with a sister named Ruth who was thirteen years his senior. His mother later recalled that he was self-taught in many areas, mathematics among them. In high school, he studied under literary critic Baruch Kurzweil, and counted among his classmates Dahlia Ravikovich, who went on to become an award-winning poet. He received his bachelor's degree from Hebrew University of Jerusalem in 1961, then crossed the Atlantic to earn his doctorate in psychology from the University of Michigan in Ann Arbor in 1965. By that point, according to those who knew him, he had already formed a clear vision of the kind of research he intended to pursue. Much of his earliest scholarly work concerned the foundations of measurement itself, a line of inquiry he pursued as co-author of a three-volume treatise called Foundations of Measurement. That grounding in formal rigor would prove essential to everything that followed.

• 3. The Paratrooper and the Decoration

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  In 1956, Tversky's platoon commander role put him in front of the IDF General Staff during a training exercise. One of his soldiers was tasked with clearing a barbed wire fence using a bangalore torpedo. After activating the fuse, the soldier panicked and froze in place rather than running to safety. Tversky disregarded his commanding officer's order for everyone to stay behind cover. He sprinted into the open, grabbed the soldier, hauled him ten yards, threw him to the ground, and shielded him with his own body. The explosion sent shrapnel into Tversky, fragments that remained inside him for the rest of his life. The soldier was unharmed. IDF Chief of Staff Moshe Dayan, who witnessed the incident, presented Tversky with his decoration and told him, "you did a very stupid and brave thing and you won't get away with it again." Tversky eventually made more than fifty parachute jumps and rose to the rank of captain. He participated in three wars in total: parachuting into combat during the Suez Crisis in 1956, commanding an infantry unit during the Six-Day War in 1967, and serving in a psychology field unit during the Yom Kippur War in 1973.

• 4. The Partnership With Kahneman

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  The collaboration with Daniel Kahneman began in the late 1960s and would become one of the most productive partnerships in the history of social science. Their first paper together was titled "Belief in the Law of Small Numbers," and from that starting point they identified eleven distinct cognitive illusions that distort human judgment. They introduced the formal notion of cognitive bias in 1972. Small-scale empirical experiments were their preferred method: controlled scenarios designed to catch people making irrational choices under uncertain conditions. Their 1974 article in Science on cognitive illusions triggered what one account later described as a "cascade of related research." Decision theorists working in economics, business, philosophy, and medicine all cited their findings. The work was highly influential precisely because economics had largely assumed that all actors behave rationally, and Tversky and Kahneman were producing systematic evidence that they do not. Their most celebrated joint achievement was prospect theory, which attempts to explain why people make economically irrational choices, and which is now considered a founding text of behavioral economics. According to Kahneman, the collaboration "tapered off" in the early 1980s, partly because Tversky received a disproportionate share of the external credit for work that was genuinely joint.

• 5. Mapping the Errors of Judgment

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  Prospect theory was only one point on a very long map of human error that Tversky helped draw. Among the ideas and frameworks that trace back to his research are anchoring and adjustment, the availability heuristic, the base rate fallacy, the conjunction fallacy, loss aversion, the representativeness heuristic, the Tversky index, support theory, framing effects, and the contrast model of similarity. One particularly counterintuitive finding emerged from joint work Tversky published with Kahneman in 1995 on what they called the comparative ignorance framework. Their argument addressed why people avoid ambiguous gambles. They found that people are only averse to ambiguity when a side-by-side comparison makes the ambiguity visible. Shown two urns at the same time, one with known proportions of colored balls and one with unknown proportions, people will bet more on the known urn. But when evaluating each urn separately, they bet roughly the same amount on each. The discomfort with ambiguity, in other words, is not a fixed property of the gamble. It depends entirely on what else is visible at the same moment. Tversky also collaborated throughout his career with Thomas Gilovich, Itamar Simonson, Paul Slovic, and Richard Thaler.

• 6. The Man Behind the Work

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  Kahneman described Tversky as having "simply perfect taste in choosing problems" and said he never wasted much time on anything that was not destined to matter. Persi Diaconis, a mathematics professor at Stanford, offered a warmer observation: "You were happy being in his presence. There was a light shining out of him." Stanford president Gerhard Casper praised his professional ethics and called his dedication to the institution's faculty governance exemplary. Tversky joined Stanford's Department of Psychology faculty in 1978 and spent the rest of his career there. Despite his reputation as a collaborator, he also kept a lifelong habit of working alone through the night while others slept. In intellectual debate, colleagues noted, he wanted to crush the opposition. He married American psychologist Barbara Gans in 1963; she later became a professor in the human-development department at Teachers College, Columbia University. They had three children. Tversky was Jewish and atheist. A Review of General Psychology survey published in 2002 ranked him as the 93rd most cited psychologist of the twentieth century, placing him alongside Edwin Boring, John Dewey, and Wilhelm Wundt. He received the MacArthur Fellowship in 1984 and was elected to the National Academy of Sciences in 1985. In 1980, he became a fellow of the American Academy of Arts and Sciences.

• 7. Legacy and the Prize He Never Held

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  Tversky died of metastatic melanoma on the 2nd of June 1996. The Nobel rules do not permit posthumous awards. When Daniel Kahneman accepted the 2002 Nobel Memorial Prize in Economic Sciences, he was explicit that the recognition encompassed work done with Tversky. Kahneman and Tversky also shared the 2003 University of Louisville Grawemeyer Award for Psychology. In popular culture, Tversky's reputation reached readers through Michael Lewis's 2016 book The Undoing Project: A Friendship That Changed Our Minds, which examined the personal and professional bond between the two men. Canadian writer Malcolm Gladwell recounted in his 2013 book David and Goliath a test that Tversky's peers invented to measure raw intelligence: the faster you realized Tversky was smarter than you, the smarter you were. Psychologist Adam Alter passed this anecdote on to Gladwell. The shrapnel that entered Tversky's body during that training exercise in 1956 never left him, and neither, it seems, did the habits of a man who understood that decisive action under uncertainty was not a failure of rationality but sometimes its highest expression.