22  Expertise and bias

There is considerable evidence that learning can lead to behaviour more closely approximating optimal behaviour over time. If that is the case, experts may be less prone to biases than non-experts.

• Goodie and Fantino (1999) found that as experimental subjects gained expertise over the course of 1600 trials, the subjects shifted from exhibiting substantial base rate neglect to near-optimality.

• Hertwig et al. (2003) found that hindsight bias - the tendency to believe that you knew how things would turn out all along - was markedly lower in experts. The more comprehensive someone’s knowledge in foresight, the smaller their hindsight bias.

• Bornstein et al. (1999) asked medical experts and undergraduate students to consider options in medical and non-medical settings. For medical decisions, the experts showed no sunk cost effect. However, both the medical experts and students showed sunk cost bias in the non-medical scenarios.

• List (2002) asked professional baseball card dealers and non-experts to value a bundle of 10 baseball cards. They were also asked to value a 13-card bundle, which included the original 10 cards plus three inferior cards. When non-experts considered them in isolation, they preferred the 10-card bundle. They preferred the 13-card bundle when comparing them side-by-side. Expert card dealers did not show this preference reversal.

• Similarly, List (2003) showed that experienced baseball card dealers do not exhibit an endowment effect.

22.1 The narrowness of expertise

As implied in the finding of Bornstein et al. (1999), expertise is narrow. There is little evidence that general skills underlie expert performance. Working memory, attention and learning speed are not generally better in experts. Instead, the perceptual, memory and cognitive components directly related to the task are better (Newell et al., 2007).

Bornstein, B. H., Christine Emler, A., and Chapman, G. B. (1999). Rationality in medical treatment decisions: Is there a sunk-cost effect? Social Science & Medicine, 49(2), 215–222. https://doi.org/10.1016/S0277-9536(99)00117-3

Goodie, A. S., and Fantino, E. (1999). What does and does not alleviate base-rate neglect under direct experience. Journal of Behavioral Decision Making, 12(4), 307–335. https://doi.org/10.1002/(SICI)1099-0771(199912)12:4<307::AID-BDM324>3.0.CO;2-H

Hertwig, R., Fanselow, C., and Hoffrage, U. (2003). Hindsight bias: How knowledge and heuristics affect our reconstruction of the past. Memory, 11(4-5), 357–377. https://doi.org/10.1080/09658210244000595

List, J. A. (2002). Preference reversals of a different kind: The "more is less" phenomenon. The American Economic Review, 92(5), 1636–1643. https://doi.org/10.1257/000282802762024692

List, J. A. (2003). Does market experience eliminate market anomalies? Quarterly Journal of Economics, 118(1), 41. https://doi.org/10.1162/00335530360535144

Newell, B. R., Lagnado, D. A., and Shanks, D. R. (2007). Straight choices: The psychology of decision making. Psychology Press.