Sweet-taste liking is associated with preference for less risky and immediate rewards in economic decision-making

Background Delay discounting refers to the tendency to choose sooner, smaller rewards over larger, later rewards. Many previous studies link this tendency positively to reward sensitivity, yet the specific mechanisms behind this association remain poorly understood. Reward sensitivity may relate to delay discounting through at least three possible pathways: increased sensitivity to reward size, increased sensitivity to reward immediacy, or increased sensitivity to risk. In this study, we use a biologically grounded measure of reward sensitivity, reflected by hedonic preference for sweet taste, to identify which of these mechanisms may be involved in the relationship between reward sensitivity and delay discounting. Methods In the first experiment ( N = 49), participants performed a standardized Kampov-Polevoy sweet-taste liking test, a lottery choice task, and a Balloon Analogue Risk Task (BART). Reward sensitivity was measured using the Kampov-Polevoy sweet-taste liking test, which categorizes participants into sweet-likers and sweet-dislikers based on their liking ratings of sucrose solutions. Regression analysis was used to examine whether the sweet-liking phenotype was significantly associated with risk-taking propensity. In the second experiment ( N = 100), participants completed the same sweet-liking test, and the lottery choice task as in Experiment 1, along with the delay discounting task to evaluate impulsivity. Regression analysis was used to analyze the association between the sweet-liking phenotype and delay discounting and to test whether this relationship is explained by differences in the sensitivity to reward size, reward immediacy, or risk preferences between the sweet-liking phenotypes. Results In Experiment 1, sweet-likers were more risk-aversive compared to sweet-dislikers in a lottery choice task, although no such effect was observed in the BART task. The same tendency toward risk aversion was observed in Experiment 2. In the delay discounting task, sweet-liking participants showed greater preference for sooner smaller reward which was associated with increased sensitivity to the reward immediacy, and not reward size. However, this relationship was partly explained by the greater risk aversion of the sweet-likers compared to sweet-dislikers. Conclusion Our results suggest that the positive relationship between reward sensitivity and impulsivity may be explained by a stronger preference for certain rewards, rather than a heightened desire for immediate rewards.