Time preferences are reliable across time-horizons and verbal versus experiential tasks

Abstract

Individual differences in delay-discounting correlate with important real world outcomes, for example education, income, drug use, and criminality. As such, delay-discounting has been extensively studied by economists, psychologists and neuroscientists to reveal its behavioral and biological mechanisms in both human and non-human animal models. However, two major methodological differences hinder comparing results across species. Human studies present long time-horizon options verbally, whereas animal studies employ experiential cues and short delays. To bridge these divides, we developed a novel language-free experiential task inspired by animal decision-making studies. We found that the ranks of subjects’ time-preferences were reliable across both verbal/experiential and second/day differences. Yet, discount factors scaled dramatically across the tasks, indicating a strong effect of temporal context. Taken together, this indicates that individuals have a stable, but context-dependent, time-preference that can be reliably assessed using different methods, providing a foundation to bridge studies of time-preferences across species.Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

Temporal discounting when outcomes are experienced in the moment: Validation of a novel paradigm and comparison with a classic hypothetical intertemporal choice task

“…The lack of correlation between tasks observed here is in line with the results of Johnson [ 38 ], who similarly found that decisions across an experiential task (using coins immediately available) and a hypothetical task (using hypothetical amounts of money) were not significantly correlated. The results, however, contrast with those of Lukinova and colleagues [ 37 ] whose experiential task used rewards that could be experienced less directly (depiction of money on a computer screen). Taken together, these results may point to the consumability of rewards as an important feature of experiential tasks; that is, it may be critical that rewards are available to direct experience if they are to inform the value of subsequent choices.…”

“…Because of experimental constraints, the experiential and hypothetical intertemporal choice tasks necessarily differed not only in the experience of delays and rewards, but also in the time scale of the delays (seconds versus days to years), the costs incurred by the delays, and the nature of the rewards. Differences in time scale are unlikely to explain our findings, as evidence suggests that subjective value brain signals during intertemporal choice tasks adapt to the range of values employed in the experimental context [ 35 ], and correlations across tasks with distinct temporal scales have been reported with monetary rewards [ 37 ]. Differences in costs associated with the delay have been highlighted as a key confound in comparisons between experiential and hypothetical intertemporal choice tasks [ 122 ] and were also present in the current study: the experiential task required waiting for the reward without distraction (high delay cost), whereas the hypothetical task did not specify the conditions of the hypothetical delay, and therefore participants could presumably resume normal daily life during that period of time (low to no delay cost).…”

“…A number of experiential intertemporal choice tasks have been developed over the years, with delays spanning seconds to minutes and varying rewards, including U.S. dollar coins [38], visual or verbal representations of money on screens [37,[47][48][49][50], squirts of water or juice [51,52], food [53,54], pictures of socially attractive faces [55], sexually-arousing pictures [11], short cartoon videos [56], and video games [57,58]. Arguably, the use of perceptual rewards is preferrable to the use of food or money: food may offer limited incentive for well-nourished participants and has been suggested to heavily depend on personal preferences [32]; and money, a secondary reinforcer, likely elicits a less direct experience of reward consumption in the moment.…”

“…Studies that have directly compared participants’ choices with experiential and hypothetical outcomes are scarce and have reported mixed findings. Using as outcomes delivered in real-time depictions of numerical amounts of money or of coins piling up on a computer screen with later exchange for actual money, two studies found that such experiential decisions were significantly correlated with those in a hypothetical monetary task [ 36 , 37 ]. By contrast, in another study that used monetary coins directly delivered to participants via a computer-connected slot machine, no correlation was observed with hypothetical decisions, suggesting that the tasks are mediated differently [ 38 ].…”

Effect of Presentation Format on Judgment of Long-Range Time Intervals

“…The hypothesis that people rather focus on numbers than the accompanying units is corroborated by findings that cooperation level of participants in the prisoner’s dilemma game increased when the reward was increased from 3ȼ to 300ȼ, but not when it was increased from 3ȼ to 3$ (Furlong and Opfer, 2009). However, presentation format does not always alter time-preferences (Lukinova et al, 2019). In an intertemporal decision making study, time-intervals were indicated textually (ex.…”