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Loss aversion is the tendency to feel a loss more strongly than a gain of the same size. Daniel Kahneman and Amos Tversky described it in 1979, and it helps explain why many people turn down a coin toss that would win them 150 on heads but lose them 100 on tails.

Kahneman and Tversky, 1979

Mind

The story behind the card

Kahneman and Tversky, two Israeli psychologists, made loss aversion a central part of prospect theory, their account of how people really make decisions under risk, published in the journal Econometrica. Kahneman received the Nobel Prize in economics in 2002; Tversky had died in 1996. A famous example is the endowment effect: in experiments published in 1990, students given a coffee mug asked more than twice as much to sell it as other students were willing to pay for it. The popular rule that losses weigh about twice as much as gains has held up on average: a 2024 review of 607 estimates from 150 studies found an average ratio close to two. Individual estimates still vary widely with the person, the task and how choices are framed, and some researchers argue the effect is weaker in everyday decisions than once believed.

Türkçe oku
Kayıptan kaçınma, bir kaybın aynı büyüklükteki bir kazançtan daha ağır gelmesidir. Daniel Kahneman ile Amos Tversky bunu 1979'da ortaya koydu. Pek çok kişinin, tura gelirse 150 kazanacağı, yazı gelirse 100 kaybedeceği bir yazı tura oyununu geri çevirmesi de bu yüzdendir.
Kahneman ve Tversky, 1979

İsrailli iki psikolog, Kahneman ile Tversky, kayıptan kaçınmayı beklenti kuramının (prospect theory) merkezine yerleştirdi. Econometrica dergisinde yayımlanan bu kuram, insanların risk altında gerçekte nasıl karar verdiğini açıklar. Kahneman 2002'de Nobel Ekonomi Ödülü'nü aldı; Tversky 1996'da ölmüştü. Bilinen bir örnek, sahiplik etkisidir: 1990'da yayımlanan deneylerde, kendilerine kahve kupası verilen öğrenciler kupayı satmak için, öteki öğrencilerin ödemeye razı olduğunun iki katından fazlasını istedi. Kayıpların kazançlardan yaklaşık iki kat ağır geldiğine dair yaygın kural, ortalamada doğrulandı: 150 çalışmadan derlenen 607 tahmini inceleyen 2024 tarihli bir derleme, ortalama oranı ikiye yakın buldu. Yine de tahminler kişiye, göreve ve seçeneklerin nasıl sunulduğuna göre büyük farklar gösterir; bazı araştırmacılar etkinin gündelik kararlarda sanıldığından zayıf olduğunu savunur.

Sources and further reading

Background reading: Loss aversion
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