Daniel Kahneman

Kahneman began his academic career as a lecturer in psychology at the Hebrew University of Jerusalem in 1961.[5] He was promoted to senior lecturer in 1966. His early work focused on visual perception and attention. For example, his first publication in the prestigious journal Science was entitled "Pupil Diameter and Load on Memory" (Kahneman & Beatty, 1966). During this period, Kahneman was a visiting scientist at the University of Michigan (1965–66) and the Applied Psychology Research Unit in Cambridge (1968/1969, summers). He was a fellow at the Center for Cognitive Studies, and a lecturer in cognitive psychology at Harvard University in 1966/1967.

This period marks the beginning of Kahneman's lengthy collaboration with Amos Tversky. Together, Kahneman and Tversky published a series of seminal articles in the general field of judgment and decision-making, culminating in the publication of their prospect theory in 1979 (Kahneman & Tversky, 1979). Following this, the pair teamed with Paul Slovic to edit a compilation entitled "Judgement Under Uncertainty: Heuristics and Biases" (1982) that proved to be an important summary of their work and of other recent advances that had influenced their thinking. Kahneman was ultimately awarded the Nobel Memorial Prize in Economics in 2002 for his work on prospect theory.

In his Nobel biography Kahneman states that his collaboration with Tversky began after Kahneman had invited Tversky to give a guest lecture to one of Kahneman's seminars at Hebrew University in 1968 or 1969.[5] Their first jointly written paper, "Belief in the Law of Small Numbers," was published in 1971 (Tversky & Kahneman, 1971). They published seven articles in peer-reviewed journals in the years 1971–1979. Aside from "Prospect Theory," the most important of these articles was "Judgment Under Uncertainty: Heuristics and Biases" (Tversky & Kahneman, 1974), which was published in the prestigious journal Science and introduced the notion of anchoring. Kahneman wrote the paper at the Van Leer Jerusalem Institute.[7]

Kahneman left Hebrew University in 1978 to take a position at the University of British Columbia.[5]

In 2021, Kahneman and co-authors Olivier Sibony and Cass Sunstein contributed to the field with work on unwanted variability in human judgments of the same problem, what they term 'noise'. In Noise: A Flaw in Human Judgment, they write that due to factors such as cognitive biases, group dynamics, mood, stress, fatigue, and differences in skill between assessors/decision makers/judges, judgements that should ideally be identical in fact often differ a lot. This gives rise to injustices, hazards and costs of various types. Furthermore, it does so in a way that is distinct from statistical bias and which is affected by cognitive biases but not limited to their influence. In the book, which received much press, they explain what noise is, how it can be detected and how it can be reduced – which can also reduce bias.

Kahneman and Tversky were both fellows at the Center for Advanced Study in the Behavioral Sciences at Stanford University in the academic year 1977–1978. A young economist named Richard Thaler was a visiting professor at the Stanford branch of the National Bureau of Economic Research during that same year. According to Kahneman, "[Thaler and I] soon became friends, and have ever since had a considerable influence on each other's thinking."[5] Building on prospect theory and Kahneman and Tversky's body of work, Thaler published "Toward a Positive Theory of Consumer Choice" in 1980, a paper which Kahneman has called "the founding text of behavioral economics."[5]

Kahneman and Tversky became heavily involved in the development of this new approach to economic theory, and their involvement in this movement had the effect of reducing the intensity and exclusivity of their earlier period of joint collaboration. According to Kahneman the collaboration 'tapered off' in the early 1980s, although they tried to revive it.[8] Factors included Tversky receiving most of the external credit for the output of the partnership, and a reduction in the generosity with which Tversky and Kahneman interacted with each other.[9] They would continue to publish together until the end of Tversky's life, but the period when Kahneman published almost exclusively with Tversky ended in 1983, when he published two papers with Anne Treisman, his wife since 1978.

In the 1990s, Kahneman's research focus began to gradually shift in emphasis towards hedonic psychology. According to Kahneman and colleagues,

Hedonic psychology...is the study of what makes experiences and life pleasant or unpleasant. It is concerned with feelings of pleasure and pain, of interest and boredom, of joy and sorrow, and of satisfaction and dissatisfaction. It is also concerned with the whole range of circumstances, from the biological to the societal, that occasion suffering and enjoyment.[10]

(This subfield is closely related to the positive psychology movement, which was steadily gaining in popularity at the time.)

It is difficult to determine precisely when Kahneman's research began to focus on hedonics, although it likely stemmed from his work on the economic notion of utility. After publishing multiple articles and chapters in all but one of the years spanning the period 1979–1986 (for a total of 23 published works in 8 years), Kahneman published exactly one chapter during the years 1987–1989. After this hiatus, articles on utility and the psychology of utility began to appear (e.g., Kahneman & Snell, 1990; Kahneman & Thaler, 1991; Kahneman & Varey, 1991).

In 1992 Varey and Kahneman introduced the method of evaluating moments and episodes as a way to capture "experiences extended across time". While Kahneman continued to study decision-making (e.g., Kahneman, 1992, 1994; Kahneman & Lovallo, 1993), hedonic psychology was the focus of an increasing number of publications (e.g., Fredrickson & Kahneman, 1993; Kahneman, Fredrickson, Schreiber & Redelemeier, 1993; Kahneman, Wakker & Sarin, 1997; Redelmeier & Kahneman, 1996), culminating in a volume co-edited with Ed Diener and Norbert Schwarz, scholars of affect and well-being.[11]

With David Schkade, Kahneman developed the notion of the focusing illusion (Kahneman & Schkade, 1998; Kahneman, Krueger, Schkade, Schwarz & Stone, 2006) to explain in part the mistakes people make when estimating the effects of different scenarios on their future happiness (also known as affective forecasting, which has been studied extensively by Daniel Gilbert). The "illusion" occurs when people consider the impact of one specific factor on their overall happiness, they tend to greatly exaggerate the importance of that factor, while overlooking the numerous other factors that would in most cases have a greater impact.

A good example is provided by Kahneman and Schkade's 1998 paper "Does living in California make people happy? A focusing illusion in judgments of life satisfaction".[12] In that paper, students in the Midwest and in California reported similar levels of life satisfaction, but the Midwesterners thought their Californian peers would be happier. The only distinguishing information the Midwestern students had when making these judgments was the fact that their hypothetical peers lived in California. Thus, they "focused" on this distinction, thereby overestimating the effect of the weather in California on its residents' satisfaction with life.

One of the cognitive biases in hedonic psychology discovered by Kahneman is called the peak–end rule. It affects how we remember the pleasantness or unpleasantness of experiences. It states that our overall impression of past events is determined for the most part not by the total pleasure and suffering it contained but by how it felt at its peaks and at its end.[13] For example, the memory of a painful colonoscopy is improved if the examination is extended by three minutes in which the scope is still inside but not moved anymore, resulting in a moderately uncomfortable sensation. This extended colonoscopy, despite involving more pain overall, is remembered less negatively due to the reduced pain at the end. This even increases the likelihood for the patient to return for subsequent procedures.[14] Kahneman explains this distortion in terms of the difference between two selves: the experiencing self, which is aware of pleasure and pain as they are happening, and the remembering self, which shows the aggregate pleasure and pain over an extended period of time. The distortions due to the peak–end rule happen on the level of the remembering self. Our tendency to rely on the remembering self can often lead us to pursue courses of action that are not in our best self-interest.[15][16][17][18]

Kahneman has defined happiness as "what I experience here and now",[19] but says that in reality humans pursue life satisfaction, which "is connected to a large degree to social yardsticks–achieving goals, meeting expectations."[20][21][22]

Kahneman is a senior scholar and faculty member emeritus at Princeton University's Department of Psychology and Princeton School of Public and International Affairs. He is also a fellow at Hebrew University and a Gallup Senior Scientist.[23]