Prior research has shown that people mispredict their own behavior and preferences across affective states. When people are in an affectively “cold” state, they fail to fully appreciate how “hot” states will affect their own preferences and behavior. When in hot states, they underestimate the influence of those states and, as a result, overestimate the stability of their current preferences. The same biases apply interpersonally; for example, people who are not affectively aroused underappreciate the impact of hot states on other people's behavior. After reviewing research documenting such intrapersonal and interpersonal hot–cold empathy gaps, this article examines their consequences for medical, and specifically cancer-related, decision making, showing, for example, that hot–cold empathy gaps can lead healthy persons to expose themselves excessively to health risks and can cause health care providers to undertreat patients for pain.

Affect has the capacity to transform us, as human beings, profoundly; in different affective states, it is almost as if we are different people.  ^{[  1  ]}  Affect influences virtually every aspect of human functioning: perception, attention, inference, learning, memory, goal choice, physiology, reflexes, self-concept, and so on. Indeed, it has been argued that the very function of affect is to orchestrate a comprehensive response to critical situations that were faced repeatedly in the evolutionary past (Cosmides & Tooby, 2000).

The dramatic transformations wrought by affect have important consequences for decision making. The foundation of decision theory is that people attempt to satisfy their long-term preferences, but people often behave myopically under the influence of affect, maximizing short-term gratification with inadequate attention to long-term consequences (Baumeister, Heatherton, & Tice, 1994; Loewenstein, 1996). Affect is clearly an essential input into decision making (e.g., Damasio, 1994), but it can also cause people to lose control of their own behavior, rendering decision making—that is, the deliberate weighing of costs and benefits—largely irrelevant.

Beyond the role that it plays in self-destructive behavior, affect complicates decision making in another way. Perhaps exactly because it has such...