Lisa Rosenbaum considers how doctors and patients approach medical decisions, examining the influence of the “affect heuristic,” which is defined as “the role that emotions play in our perceptions of benefit and risk”:
When affect guides our decisions, we are far more sensitive to possibility than to probability. In one experiment, some subjects were asked how much they were willing to pay to avoid a potential loss of twenty dollars; others were asked how much they would pay to avoid a potential electric shock. The people asked about the shock paid about the same amount of money, regardless of whether the probability of receiving it was one per cent or ninety-nine per cent. The responses of people asked about the monetary loss, however, tracked more closely to the associated probabilities. The mere possibility of risk, no matter how small, drives our behavior.
How might this tendency play out in medicine? Take, for instance, the increasing rate of women with breast cancer pursuing prophylactic double mastectomy—most famously, Angelina Jolie. For most women with breast cancer, the risk of later developing breast cancer in the other breast is low, meaning the risks of mastectomy outweigh the benefits. Indeed, a recent survey of women who had undergone prophylactic mastectomy found that some seventy per cent would derive little survival benefit. Nevertheless, ninety per cent of those women reported that they were “very worried” about breast-cancer recurrence. In other words, in the setting of fear, the possibility of recurrence, rather than its actual probability, fuels decisions that, over all, likely cause more harm than good.