Exchanging the liquidity hypothesis: Delay discounting of money and self-relevant non-money rewards

Contextual factors modulate risk preferences in adult humans

Humans have generally been considered risk averse for gains. Yet, growing evidence shows that risk preferences may change across reward currencies and depend on the type of tasks used to measure them. Here, we examined how context affects human risk preferences to shed light on the psychological mechanisms underlying human decision-making under risk. Participants were presented with a descriptive risky choice task involving repeated choices between real options and they were provided with trial-by-trial feedback. We manipulated the type of reward and, for the first time, the format of the choice stimuli. Options were either 2D computer-based images or concrete 3D objects, and participants received food or money as reward. First, we found that participants were more risk-seeking for food compared to money, suggesting that people treat money differently from consumable rewards. Second, we found that people were more risk-seeking when they made choices between concrete 3D objects than between 2D computer-based images. Our results strengthened the evidence that human choice patterns may change depending on the context and, for the first time, showed that the format of the choice stimuli does affect risk preferences, an important consideration for future research.

Delay discounting of different outcomes: Review and theory

Steep delay discounting is characterized by a preference for small immediate outcomes relative to larger delayed outcomes and is predictive of drug abuse, risky sexual behaviors, and other maladaptive behaviors. Nancy M. Petry was a pioneer in delay discounting research who demonstrated that people discount delayed monetary gains less steeply than they discount substances with abuse liability. Subsequent research found steep discounting for not only drugs, but other nonmonetary outcomes such as food, sex, and health. In this systematic review, we evaluate the hypotheses proposed to explain differences in discounting as a function of the type of outcome and explore the trait- and state-like nature of delay discounting. We found overwhelming evidence for the state-like quality of delay discounting: Consistent with Petry and others' work, nonmonetary outcomes are discounted more steeply than monetary outcomes. We propose two hypotheses that together may account for this effect: Decreasing Future Preference and Decreasing Future Worth. We also found clear evidence that delay discounting has trait-like qualities: People who steeply discount monetary outcomes steeply discount nonmonetary outcomes as well. The implication is that changing delay discounting for one outcome could change discounting for other outcomes.