Hypothetical Rewards Research Articles

BOLD responses in reward regions to hypothetical and imaginary monetary rewards

Monetary rewards are uniquely human. Because money is easy to quantify and present visually, it is the reward of choice for most fMRI studies, even though it cannot be handed over to participants inside the scanner. A typical fMRI study requires hundreds of trials and thus small amounts of monetary rewards per trial (e.g. 5p) if all trials are to be treated equally. However, small payoffs can have detrimental effects on performance due to their limited buying power. Hypothetical monetary rewards can overcome the limitations of smaller monetary rewards but it is less well known whether predictors of hypothetical rewards activate reward regions. In two experiments, visual stimuli were associated with hypothetical monetary rewards. In Experiment 1, we used stimuli predicting either visually presented or imagined hypothetical monetary rewards, together with non-rewarding control pictures. Activations to reward predictive stimuli occurred in reward regions, namely the medial orbitofrontal cortex and midbrain. In Experiment 2, we parametrically varied the amount of visually presented hypothetical monetary reward keeping constant the amount of actually received reward. Graded activation in midbrain was observed to stimuli predicting increasing hypothetical rewards. The results demonstrate the efficacy of using hypothetical monetary rewards in fMRI studies.

Real and hypothetical rewards in self-control and social discounting

AbstractLaboratory studies of choice and decision making among real monetary rewards typically use smaller real rewards than those common in real life. When laboratory rewards are large, they are almost always hypothetical. In applying laboratory results meaningfully to real-life situations, it is important to know the extent to which choices among hypothetical rewards correspond to choices among real rewards and whether variation of the magnitude of hypothetical rewards affects behavior in meaningful ways. The present study compared real and hypothetical monetary rewards in two experiments. In Experiment 1, participants played a temporal discounting game that incorporates the logic of a repeated prisoner’s-dilemma (PD) game versus tit-for-tat; choice of one alternative (“defection” in PD terminology) resulted in a small-immediate reward; choice of the other alternative (“cooperation” in PD terminology) resulted in a larger reward delayed until the following trial. The larger-delayed reward was greater for half of the groups than for the other half. Rewards also differed in type across groups: multiples of real nickels, hypothetical nickels, or hypothetical hundred-dollar bills. All groups significantly increased choice of the larger delayed reward over the 40 trials of the experiment. Over the last 10 trials, cooperation was significantly higher when the difference between larger and smaller hypothetical rewards was greater. Reward type (real or hypothetical) made no significant difference in cooperation on most measures. In Experiment 2, real and hypothetical rewards were compared in social discounting—the decrease in value to the giver of a reward as social distance increases to the receiver of the reward. Social discount rates were well described by a hyperbolic function. Discounting rates for real and hypothetical rewards did not significantly differ. These results add to the evidence that results of experiments with hypothetical rewards validly apply in everyday life.

MODELING THE EFFECT OF REWARD AMOUNT ON PROBABILITY DISCOUNTING

The present study with college students examined the effect of amount on the discounting of probabilistic monetary rewards. A hyperboloid function accurately described the discounting of hypothetical rewards ranging in amount from $20 to $10,000,000. The degree of discounting increased continuously with amount of probabilistic reward. This effect of amount was not due to changes in the rate parameter of the discounting function, but rather was due to increases in the exponent. These results stand in contrast to those observed with the discounting of delayed monetary rewards, in which the degree of discounting decreases with reward amount due to amount-dependent decreases in the rate parameter. Taken together, this pattern of results suggests that delay and probability discounting reflect different underlying mechanisms. That is, the fact that the exponent in the delay discounting function is independent of amount is consistent with a psychophysical scaling interpretation, whereas the finding that the exponent of the probability-discounting function is amount-dependent is inconsistent with such an interpretation. Instead, the present results are consistent with the idea that the probability-discounting function is itself the product of a value function and a weighting function. This idea was first suggested by Kahneman and Tversky (1979), although their prospect theory does not predict amount effects like those observed. The effect of amount on probability discounting was parsimoniously incorporated into our hyperboloid discounting function by assuming that the exponent was proportional to the amount raised to a power. The amount-dependent exponent of the probability-discounting function may be viewed as reflecting the effect of amount on the weighting of the probability with which the reward will be received.

Risk attitude elicitation using a multi-lottery choice task: Real vs. hypothetical incentives

ABSTRACTWe present a bi-dimensional multi lottery choice task which can be used in order to elicit the agents' risk attitudes in financial environments. This task is implemented both with hypothetical and real monetary incentives in a between-subjects and a within-subjects experiment. We observe choices involving significantly lower risk aversion on aggregate when incentives are real. The differences grow with the stakes at play. We also obtain significant differences between hypothetical and real rewards in both utility weighting and probability weighting estimated parameters. We find that the use of hypothetical incentives in multi-lottery choice tasks for evaluating individual risk aversion can be misleading.

Emotion, Decision, and Risk: Betting on Gambles versus Betting on People

ABSTRACTWe examined the effects of two emotions, fear and anger, on risk‐taking behavior in two types of tasks: Those in which uncertainty is generated by a randomizing device (“lottery risk”) and those in which it is generated by the uncertain behavior of another person (“person‐based risk”). Participants first completed a writing task to induce fear or anger. They then made choices either between lotteries (Experiment 1) or between actions in risky two‐person decisions (Experiments 2 and 3). The experiments involved substantial real‐money payoffs. Replicating earlier studies (which used hypothetical rewards), Experiment 1 showed that fearful participants were more risk‐averse than angry participants in lottery‐risk tasks. However—the key result of this study—fearful participants were substantiallylessrisk‐averse than angry participants in a two‐person task involving person‐based risk (Experiment 2). Experiment 3 offered options and payoffs identical to those of Experiment 2 but with lottery‐type risk. Risk‐taking returned to the pattern of Experiment 1. The impact of incidental emotions on risk‐taking appears to be contingent on the class of uncertainty involved. For lottery risk, fear increased the frequency of risk‐averse choices and anger reduced it. The reverse pattern was found when uncertainty in the decision was person‐based. Further, the effect was specifically on differences in willingness to take risks rather than on differences in judgments of how much risk was present. The impact of different emotions on risk‐taking or risk‐avoiding behavior is thus contingent on the type, as well as the degree, of uncertainty the decision maker faces. Copyright © 2010 John Wiley & Sons, Ltd.

The effects of real versus hypothetical reward on delay and probability discounting

Delay discounting and probability discounting tasks providing hypothetical rewards have commonly been used to measure levels of impulsivity and risk taking. Results have been inconsistent as to whether real, compared with hypothetical, rewards influence choice behaviour in delay discounting tasks. This experiment examined choice behaviour in 38 healthy individuals using delay and probability discounting tasks involving both real and hypothetical rewards (pound sterling 0.10/pound sterling 0.20), real delays, and probabilistic outcomes. It was hypothesized that choice behaviour when receiving real rewards would be less impulsive and less risky than when receiving hypothetical rewards. The tasks were designed so that a mathematical model (the multiplicative hyperbolic model of choice) could be applied to assess effects on discounting parameters. The provision of real rewards was associated with significantly decreased impulsive, but not risky, choice although the size of effect was small and was influenced by the order of presentation. Repeated presentation of both tasks increased quantity discounting but not delay or probability discounting parameters. These results indicate that the nature of the reward provided, and repetition effects, need to be taken into account when designing discounting studies.

Effects of methylphenidate on discounting of delayed rewards in attention deficit/hyperactivity disorder.

Impulsivity is a central component of attention deficit/hyperactivity disorder (ADHD). Delay discounting, or a preference for smaller, immediate rewards over larger, delayed rewards, is considered an important aspect of impulsivity, and delay-related impulsivity has been emphasized in etiological models of ADHD. In this study, we examined whether stimulant medication, an effective treatment for ADHD, reduced discounting of delayed experiential and hypothetical rewards among 49 children (ages 9-12 years) with ADHD. After a practice day, participants completed a 3-day double-blind placebo-controlled acute medication assessment. Active doses were long-acting methylphenidate (Concerta), with the nearest equivalents of 0.3 and 0.6 mg/kg TID immediate-release methylphenidate. On each testing day, participants completed experiential (real-world money in real time) and hypothetical discounting tasks. Relative to placebo, methylphenidate reduced discounting of delayed experiential rewards but not hypothetical rewards. Broadly consistent with etiological models that emphasize delay-related impulsivity among children with ADHD, these findings provide initial evidence that stimulant medication reduces delay discounting among those with the disorder. The results also draw attention to task parameters that may influence the sensitivity of various delay discounting measures to medication effects.

Dynamically Inconsistent Preferences and Money Demand

This paper focuses on two main issues. First, we find that, on average, households' discount rates decline. This implies dynamically inconsistent preferences. Second, we calculate an indicator of the degree of dynamic inconsistency that may help us to understand how households overcome their self-control problems. We use a micro dataset containing households' reports on the compensation for receiving hypothetical rewards with delays. We find that individuals with more severely dynamically inconsistent preferences on average hold a statistically significantly lower share of their total wealth in checking accounts. A possible interpretation is that subjects use precommitment strategies to limit their temptation to consume immediately.

Patience

Patience

How reinforcer type affects choice in economic games

Behavioral economists stress that experiments on judgment and decision-making using economic games should be played with real money if the results are to have generality. Behavior analysts have sometimes disputed this contention and have reported results in which hypothetical rewards and real money have produced comparable outcomes. We review studies that have compared hypothetical and real money and discuss the results of two relevant experiments. In the first, using the Sharing Game developed in our laboratory, subjects' choices differed markedly depending on whether the rewards were real or hypothetical. In the second, using the Ultimatum and Dictator Games, we again found sharp differences between real and hypothetical rewards. However, this study also showed that time off from a tedious task could serve as a reinforcer every bit as potent as money. In addition to their empirical and theoretical contributions, these studies make the methodological point that meaningful studies may be conducted with economic games without spending money: time off from a tedious task can serve as a powerful reward.

Time and decision making: differential contribution of the posterior insular cortex and the striatum during a delay discounting task

Delay discounting refers to the fact that an immediate reward is valued more than the same reward if it occurs some time in the future. To examine the neural substrates underlying this process, we studied 13 healthy volunteers who repeatedly had to decide between an immediate and parametrically varied delayed hypothetical reward using a delay discounting task during event-related functional magnetic resonance imaging. Subject's preference judgments resulted in different discounting slopes for shorter (<1 year) and for longer (> or =1 year) delays. Neural activation associated with the shorter delays relative to the longer delays was associated with increased activation in the head of the left caudate nucleus and putamen. When individuals selected the delayed relative to the immediate reward, a strong activation was found in bilateral posterior insular cortex. Several brain areas including the left caudate nucleus showed a correlation between the behaviorally determined discounting and brain activation for the contrast of intervals with delays <1 and > or =1 year. These results suggest that (1) the posterior insula, which is a critical component of the decision-making neural network, is involved in delaying gratification and (2) the degree of neural activation in the striatum, which plays a fundamental role in reward prediction and in time estimation, may code for the time delay.

確率による報酬の価値割引‐現実場面と仮想場面の比較‐

In Experiment 1, undergraduates first made choices hypothetically between an uncertain large reward and a certain small reward, second they made choices with real money, and finally they again made hypothetical choices. The discounting rates in the first hypothetical reward condition were higher than those in the following conditions of real or hypothetical rewards. A significant difference in the discounting rate across conditions was not found when the real reward condition was replaced by the hypothetical reward condition (Experiment 2) or by the condition with probability contingency and hypothetical reward (Experiment 3). The difference in the discounting rate was replicated between the hypothetical and real reward conditions when the participants invested money when they selected an uncertain-large reward (Experiment 4). Johnson & Bickel (2002) found no difference in the discounting rate between hypothetical and real rewards when the real rewards were delivered to participants not during but after the experiment. The present experiments, by contrast, delivered real money immediately after every choice, and demonstrate that real and hypothetical rewards differ in the values of discounting rates.

The smoking Stroop and delay discounting in smokers: effects of environmental smoking cues

We investigated the effects of exposure to environmental smoking-related cues (holding a lit cigarette in an environment previously associated with smoking) on cigarette craving, colour naming of smoking-related words in a modified Stroop task, and on the delay discounting of hypothetical rewards, in daily cigarette smokers (N = 30). Compared to exposure to neutral cues, exposure to smoking-related cues was associated with increased cigarette craving and slower colour naming of smoking-related compared to matched control words. However, smoking cues had no effect on delay discounting. These results suggest that smoking cues increase craving and the ability of smoking-related words to grab the attention, but do not influence impulsive decision-making. Theoretical and clinical implications are discussed.

The relationship between temporal discounting and the prisoner's dilemma game in intranasal abusers of prescription opioids

Previous research on college students has found that cooperation in iterated prisoner's dilemma game is correlated with preference for delayed rewards in studies of temporal discounting. The present study attempted to replicate this finding in a drug-dependent population. Thirty-one individuals who intranasally abuse prescription opioids participated in temporal discounting and iterated prisoner's dilemma game procedures during intake for a treatment study. Rate of temporal discounting was determined for each participant at two hypothetical reward magnitudes, as well as proportion of cooperation in a 60-trial iterated prisoner's dilemma game versus a tit-for-tat strategy. Cooperation in the prisoner's dilemma game and temporal discounting rates were significantly correlated in the predicted direction: individuals who preferred delayed rewards in the temporal discounting task were more likely to cooperate in the prisoner's dilemma game.

Delay discounting of real and hypothetical rewards III: Steady-state assessments, forced-choice trials, and all real rewards

Human research in delay discounting has omitted several procedures typical of animal studies: forced-choice trials, consequences following each response, and assessment of stable response patterns. The present study manipulated these procedures across two conditions in which real or hypothetical rewards were arranged. Six college students participated in daily sessions, in which steady-state discounting of hypothetical and real rewards was assessed. No systematic effects of repeated exposure to hypothetical rewards was detected when compared with first day assessments of discounting. Likewise, no systematic effect of reward type (real versus hypothetical) was detected. When combined with previous research failing to detect a difference between hypothetical and potentially real rewards, these findings suggest that assessing discounting of hypothetical rewards in single sessions is a practical and valid procedure in the study of delay discounting.

Delay Discounting of Potentially Real and Hypothetical Rewards: II. Between- and Within-Subject Comparisons.

Prior studies comparing discounting of delayed hypothetical or potentially real rewards have reported no differences, but they used within-subjects designs. This raises the possibility that participants remembered their choices in one condition and repeated them in the other. In Experiment 1, between-subjects comparisons were made with an adjusting-amount procedure. No significant effect of reward type on delay discounting was detected. Experiment 2 increased the proportion of real rewards and made between- and within-subject comparisons. These comparisons also failed to reveal a significant effect of reward type. Although these findings are consistent with prior findings, caution is urged because choices involving hypothetical rewards have yet to be compared with choices involving real rewards (i.e., the consequences of every choice are obtained) in an experiment using forced-choice trials and steady-state methodology.

Measurement of delay discounting using trial-by-trial consequences.

DELAY DISCOUNTING IN HUMANS WAS INVESTIGATED USING THREE DIFFERENT PROCEDURES: a frequently used discounting procedure with hypothetical rewards and delays; a procedure with hypothetical rewards and delays compressed down to much smaller values; and a contingent procedure in which each choice had a direct consequence. In the contingent procedure, on every trial, participants actually experienced the delay and obtained the reward amount associated with their choice. Each participant was exposed to all three procedures. Orderly temporal discounting patterns were obtained in all three procedures and described well by a hyperbolic model. Comparisons of the data revealed patterns unique to each procedure. The distributions of the discounting measures differed across the three procedures. In the contingent procedure, several subjects showed no discounting, e.g. complete self-control. Procedural factors in studies of impulsivity are discussed, and suggestions are offered for experiments in which the contingent-discounting procedure may prove useful.

Impulsivity and rapid discounting of delayed hypothetical rewards in cocaine-dependent individuals.

Impulsivity and rapid discounting of delayed hypothetical rewards in cocaine-dependent individuals.

Within-subject comparison of real and hypothetical money rewards in delay discounting.

A within-subject design, using human participants, compared delay discounting functions for real and hypothetical money rewards. Both real and hypothetical rewards were studied across a range that included $10 to $250. For 5 of the 6 participants, no systematic difference in discount rate was observed in response to real and hypothetical choices, suggesting that hypothetical rewards may often serve as a valid proxy for real rewards in delay discounting research. By measuring discounting at an unprecedented range of real rewards, this study has also systematically replicated the robust finding in human delay discounting research that discount rates decrease with increasing magnitude of reward. A hyperbolic decay model described the data better than an exponential model.

Delay discounting is associated with substance use in college students

This study investigated whether a measure of delay discounting was associated with substance use variables in a sample of college students. Participants ( N=47) completed a substance use survey and a delay-discounting measure that asked them to make a series of choices between a fixed amount of hypothetical money to be delivered immediately and a larger amount to be delivered after a range of delays. Discounting values were significantly associated with a number of substance use variables, most notably age of first alcohol use ( r=−.34; P<.05), age of first smoking ( r=−.51; P<.05), age of first marijuana use ( r=−.48; P<.05), number of times “passed out” from alcohol use ( r=.73; P<.01), and total number of illicit drugs used ( r=.32; P<.05). Individuals reporting more illicit drug use and younger ages of first use tend to discount the value of future hypothetical rewards more steeply than their peers.