Recent research has shown that risk and reward are positively correlated in many environments, and that people have internalized this association as a “risk-reward heuristic”: when making choices based on incomplete information, people infer probabilities from payoffs and vice-versa, and these inferences shape their decisions. We extend this work by examining people’s expectations about another fundamental trade-off — that between monetary reward and delay. In 2 experiments (total N = 670), we adapted a paradigm previously used to demonstrate the risk-reward heuristic. We presented participants with intertemporal choice tasks in which either the delayed reward or the length of the delay was obscured. Participants inferred larger rewards for longer stated delays, and longer delays for larger stated rewards; these inferences also predicted people’s willingness to take the delayed option. In exploratory analyses, we found that older participants inferred longer delays and smaller rewards than did younger ones. All of these results replicated in 2 large-scale pre-registered studies with participants from a different population (total N = 2138). Our results suggest that people expect intertemporal choice tasks to offer a trade-off between delay and reward, and differ in their expectations about this trade-off. This “delay-reward heuristic” offers a new perspective on existing models of intertemporal choice and provides new insights into unexplained and systematic individual differences in the willingness to delay gratification.

In clinical trials, incentivizing human research subjects with large amounts of money is often considered unethical, as it may coerce people to participate. This argument implies that people perceive rewards (i.e., incentives) independently of risks (i.e., probability of side-effects) or that they assume that larger rewards are associated with lower risks. However, past research on risk perception indicates that people associate higher rewards with higher risks. To test whether people treat incentives in clinical trials as a proxy for risk, we conducted an online experiment (N = 483) in which people estimated the riskiness of hypothetical clinical trials. We manipulated the monetary incentives that participants of the clinical trials were offered. The results show that people expect more side effects if the monetary incentives for participation are higher. Results further show that the majority of participants were more likely to ethically approve a trial if it offered a high monetary incentive. In contrast to existing ethical guidelines these results suggest that paying large rewards may be less problematic because people implicitly associate them with higher risk and because they trade-off risks and financial benefits.