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D.B. CARR
WHAT PART OF “KNOW” DON’T YOU UNDERSTAND?
Narrative is always grounded in culture, and cultures presuppose shared knowledge and beliefs (Morris 1991, 1998). Why not view culture as a nonmathematical, cumulative meta-analysis of methods for humans to adapt optimally to their surroundings? In doing so, one must make allowances for the biases that human judgment appears to have programmed within it (Piattelli-Palmarini 1994; Ninio 2001). As I observed above, we are hardwired so that the very most important things in life are approached not rationally, but affectively. The predictable misperception of classical optical illusions such as that of Franz Müller-Lyer (Fig. 2) shows that human beings are genetically programmed to make stereotypical mistakes in simple visual judgments. Tversky, Kahneman, Raiffa, and others extended this insight by documenting many inevitable “cognitive illusions” that befall normal individuals asked to make simple estimates (Kahneman et al. 1982). For example, subjects given 5 seconds to calculate the product 2 × 3 × 4 × 5 × 6 × 7 × 8 tend to estimate it as 512; matched subjects asked to estimate 8 × 7 × 6 × 5 × 4 × 3 × 2 tend to answer 2,250. These responses—both far off the actual value of 40,320—have been replicated around the world. Tversky and Kahneman conducted another experiment in which subjects were asked whether they would prefer to receive $100, or agree to a coin toss in which the winner would receive $200 and the loser nothing. Subjects in another experiment were hypothetically given $100, then asked to choose between a guaranteed loss of $20 or a coin toss where the loser pays $40 and the winner nothing. Although both choices in each experiment are equivalent, most people prefer the former choice in the first experiment and the latter choice in the second, indicating that “preferences between gains are riskaverse and preferences between losses are risk-seeking.” More colorfully expressed, “we are spontaneously conservative when it comes to winning, and adventurers when it comes to loss” (Tversky 1996). This bias extends into clinical medicine. A greater proportion of clinicians felt that they would recommend a certain operation once informed that it carries a 5-year
Fig. 2. The Müller-Lyer optical illusion. Most viewers perceive the lower horizontal line as longer. Both the upper and lower horizontal lines, however, are of equal length.
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