Larger-later Research Articles

Pigeons' (Columba livia) intertemporal choice in binary-choice and patch-leaving contexts.

Typical approaches to study self-control present subjects with a simultaneous choice between a larger-later (LL) reinforcer and a smaller-sooner (SS) reinforcer. In contrast, in patch-leaving tasks, subjects choose between staying at a patch for an SS (or LL) reinforcer and leaving for an LL (or SS) reinforcer. Previous studies show that blue jays, monkeys, humans, and rats prefer the SS reinforcer in binary-choice tasks, whereas the same subjects prefer the LL reinforcer in equivalent patch-leaving tasks. The current study systematically replicated this research using pigeons. Six pigeons responded in a binary-choice task and in two patch-leaving tasks in which staying led to an LL (Patch-L) or SS (Patch-S) reinforcer. Across conditions, the SS reinforcer delay varied from 5 to 55 s; the LL reinforcer delay was always 60 s. In binary-choice conditions, subjects preferred the SS reinforcer. In Patch-L and Patch-S conditions, subjects preferred the LL and SS reinforcer, respectively, reflecting a bias to stay at the patch. This bias persisted when the stay response was more effortful and when the delays to both reinforcers were equal. This may reflect a species-specific win-stay bias and the differential consequences of staying (which led to a stimulus signaling food) versus leaving (which led to a stimulus never associated with food). Thus, we propose a conditioned-reinforcement account of intertemporal choice in patch-leaving contexts. We suggest several avenues for further investigations of the mechanisms underlying intertemporal choice in different contexts and question the economic equivalence of the operant and patch-leaving procedures. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Active and passive waiting in impulsive choice: Effects of fixed-interval and fixed-time delays.

Behavioral interventions to improve self-control, preference for a larger-later (LL) reward over a smaller-sooner (SS) reward, involve experience with delayed rewards. Whether they involve timing processes remains controversial. In rats, there have been inconsistent results on whether timing processes may be involved in intervention-induced improvements in self-control. Interventions that improved self-control with corresponding timing improvements used fixed-interval (FI) delays, whereas interventions that failed to find corresponding timing improvements used fixed-time (FT) delays. The FI schedule includes a response contingency (active waiting), whereas the FT schedule delivers reward automatically (passive waiting). The present study compared the effects of FI and FT schedules in interventions and impulsive choice tasks to evaluate effects on self-control and timing behavior. The impulsive choice task evaluated preference for an SS option (one pellet after 10-, 15-, 20-, 25-, and 30-s delays) versus an LL option (two pellets after a 30-s delay). The intervention task included forced-choice SS (one pellet after 10 s) and LL (two pellets after 30 s) sessions under FI or FT schedules. FI schedules produced greater sensitivity to SS delay in the impulsive choice task. Both FI and FT interventions increased LL choices. Following choice testing, temporal bisection and peak interval tasks revealed better timing precision for rats with an FI delay experience. Overall, the FI choice contingency was associated with improved temporal attention and timing precision.

Mechanisms of impulsive choice: Experiments to explore and models to map the empirical terrain.

Impulsive choice is preference for a smaller-sooner (SS) outcome over a larger-later (LL) outcome when LL choices result in greater reinforcement maximization. Delay discounting is a model of impulsive choice that describes the decaying value of a reinforcer over time, with impulsive choice evident when the empirical choice-delay function is steep. Steep discounting is correlated with multiple diseases and disorders. Thus, understanding the processes underlying impulsive choice is a popular topic for investigation. Experimental research has explored the conditions that moderate impulsive choice, and quantitative models of impulsive choice have been developed that elegantly represent the underlying processes. This review spotlights experimental research in impulsive choice covering human and nonhuman animals across the domains of learning, motivation, and cognition. Contemporary models of delay discounting designed to explain the underlying mechanisms of impulsive choice are discussed. These models focus on potential candidate mechanisms, which include perception, delay and/or reinforcer sensitivity, reinforcement maximization, motivation, and cognitive systems. Although the models collectively explain multiple mechanistic phenomena, there are several cognitive processes, such as attention and working memory, that are overlooked. Future research and model development should focus on bridging the gap between quantitative models and empirical phenomena.

Intertemporal Decision-making and Risk Decision-making Among Habitual Nappers Under Nap Sleep Restriction: A Study from ERP and Time-frequency.

Sleep restriction affects people's decision-making behavior. Nap restriction is a vital subtopic within sleep restriction research. In this study, we used EEG to investigate the impact of nap sleep restriction on intertemporal decision-making (Study 1) and decision-making across risky outcomes (Study 2) from ERP and time-frequency perspectives. Study 1 found that habitual nappers restricting their naps felt more inclined to choose immediate, small rewards over delayed, large rewards in an intertemporal decision-making task. P200s, P300s, and LPP in our nap-restriction group were significantly higher than those in the normal nap group. Time-frequency results showed that the delta band (1 ~ 4Hz) power of the restricted nap group was significantly higher than that of the normal nap group. In Study 2, the nap-restriction group was more likely to choose risky options. P200s, N2s, and P300s in the nap deprivation group were significantly higher than in the normal nap group. Time-frequency results also found that the beta band (11 ~ 15Hz) power of the restricted nap group was significantly lower than that of the normal nap group. The habitual nappers became more impulsive after nap restriction and evinced altered perceptions of time. The time cost of the LL (larger-later) option was perceived to be too high when making intertemporal decisions, and their expectation of reward heightened when making risky decisions-believing that they had a higher probability of receiving a reward. This study provided electrophysiological evidence for the dynamic processing of intertemporal decision-making, risky decision-making, and the characteristics of nerve concussions for habitual nappers.

View of Times and Temporal Focus under the Pace of Life on the Impact of Intertemporal Decision Making.

Previous studies have explored the effects of time poverty and money worship on intertemporal decision making based on a resource scarcity perspective. However, how the pace of life affects intertemporal decision making has not been examined. Furthermore, manipulating time perceptions can influence intertemporal decision-making preferences. Based on the perspective of time perception differences, it remains unknown how views of time or temporal focus affect the intertemporal decision making of individuals with different pace of life. To address these issues, study 1 adopted a correlational study to initially explore the relationship between the pace of life and intertemporal decision making. Studies 2 and 3 used manipulation experiments to examine the effects of the pace of life and view of time and temporal focus and pace of life on intertemporal decision making. The results suggest that the faster the life pace, the more recent rewards are preferred. Views of time and temporal focus manipulations can influence the intertemporal decision making of faster-paced individuals, making them prefer smaller-sooner (SS) payoffs under a linear view of time or future temporal focus and larger-later (LL) payoffs under a circular view of time or past temporal focus. However, the manipulation does not affect the intertemporal decision of slower-paced individuals. Our study examined the effect of the pace of life on intertemporal decision making based on a resource scarcity perspective, and found boundary conditions for the influence of the view of time and temporal focus on intertemporal decision making based on the perspective of differences in people's perception of time.

Effects of methylphenidate on impulsive choice and delay aversion in Lewis rats.

Attention-deficit/hyperactivity disorder (ADHD), a common behavioral disorder in children and young adults, is characterized by symptoms of impulsivity, inattention, and hyperactivity. The purpose of this study was to evaluate the Lewis rat strain as a model of ADHD by testing their impulsive choices. Lewis rats were compared to their source strain, the Wistar rat, on an impulsive choice task. Rats completed the tasks on and off methylphenidate, a commonly prescribed medication for ADHD. Off methylphenidate, Lewis rats made more impulsive choices than Wistar rats. Analyses of acquisition of choice behavior suggested that both strains were able to discriminate reward sizes, but Lewis rats still chose the smaller-sooner option more than the larger-later (LL) option when the delays to reward were the same. This may be due to an aversion to the LL lever, which was associated with the longest delays to reward. Higher doses of methylphenidate increased LL choices in Lewis rats but decreased LL choices in Wistar rats. Altogether, these results suggest Lewis rats may be a viable model for ADHD in individuals whose symptoms are characterized by impulsive choices.

The brain stimulation of DLPFC regulates choice preference in intertemporal choice self-other differences

Intertemporal choice requires to make decision by evaluating the value of two options consisting of different times and benefits. The dorsolateral prefrontal cortex (DLPFC) is a key brain region for modulating intertemporal choice. The aim of this study is to investigate the effect of non-invasive brain stimulation over DLPFC on intertemporal choice behavior for self and others. We used transcranial direct current stimulation (tDCS) and continuous theta burst stimulation (cTBS) to stimulate bilateral DLPFC in two experiments respectively. After stimulation, subjects made a choice between a Smaller-Sooner (SS) reward and a Larger-Later (LL) reward in intertemporal choice task. The results showed that cTBS stimulation on the left DLPFC reduced the choice preference for SS reward when individuals made choices for themselves. The cTBS stimulation caused preference difference between choosing for self and parents. But tDCS stimulation had no effect on regulating choice preference. In addition, subjects preferred SS reward for self than strangers. Time-types and monetary difference of rewards affected the choice preference. The presence of immediate time increased the choice preference of SS reward. As the monetary difference increased, the choice proportion of SS reward decreased. Our study demonstrates that brain stimulation on the left DLPFC can regulate choice preference behavior in intertemporal choice.

Choice Bundling Increases Valuation of Delayed Losses More Than Gains in Cigarette Smokers.

Choice bundling, in which a single choice produces a series of repeating consequences over time, increases valuation of delayed monetary and non-monetary gains. Interventions derived from this manipulation may be an effective method for mitigating the elevated delay discounting rates observed in cigarette smokers. No prior work, however, has investigated whether the effects of choice bundling generalize to reward losses. In the present study, an online panel of cigarette smokers (N = 302), recruited using survey firms Ipsos and InnovateMR, completed assessments for either monetary gains or losses (randomly assigned). In Step 1, participants completed a delay-discounting task to establish Effective Delay 50 (ED50), or the delay required for an outcome to lose half of its value. In Step 2, participants completed three conditions of an adjusting-amount task, choosing between a smaller, sooner (SS) adjusting amount and a larger, later (LL) fixed amount. The bundle size (i.e., number of consequences) was manipulated across conditions, where a single choice produced either 1 (control), 3, or 9 consequences over time (ascending/descending order counterbalanced). The delay to the first LL amount in each condition, as well as the intervals between all additional SS and LL amounts (where applicable), were set to individual participants’ ED50 values from Step 1 to control for differences in discounting of gains and losses. Results from Step 1 showed significantly higher ED50 values (i.e., less discounting) for losses compared to gains (p < 0.001). Results from Step 2 showed that choice bundling significantly increased valuation of both LL gains and losses (p < 0.001), although effects were significantly greater for losses (p < 0.01). Sensitivity analyses replicated these conclusions. Future research should examine the potential clinical utility of choice bundling, such as development of motivational interventions that emphasize both the bundled health gains associated with smoking cessation and the health losses associated with continued smoking.

The effect of risk on intertemporal choice and preference reversal

Two experiments examined the effect of risk on waiting preference and temporal preference reversal. Participants made binary choices between smaller-sooner (SS) and larger-later (LL) options following a 2 (time: immediate choices vs. non-immediate choices) x 4 (risk condition) within-subjects design. Risk conditions varied in whether the SS and/or the LL was risky or certain. Experiment 1 focused on choices with small magnitudes of payoffs and delays, whereas Experiment 2 focused on large magnitudes. Both experiments showed that making one option risky increased preference for the other option, whereas making both options risky had no impact on waiting preference. Pooling risk conditions together, participants in both experiments demonstrated temporal preference reversal. However, participants showed preference reversal in all 4 risk conditions in Experiment 2, but only in the risky (SS)-certain (LL) and risky-risky conditions in Experiment 1. This finding indicates for uncertain outcomes, people were at least equally (if not more) likely to reverse their choices, compared to certain outcomes.

Generalizability of time-based interventions: Effects of choice procedure and smaller-sooner delay

Interventions exposing rats to delayed-reward contingencies attenuate suboptimal impulsive choices, a preference for a smaller-sooner (SS) over a larger-later (LL) reward. Interventions may potentially improve delay-tolerance, timing of delays, and/or discrimination of reward magnitudes. Generalization from the intervention to impulsive choice under different procedures can provide insights into the processes that underlie the intervention effects. Experiment 1 tested intervention effects on systematic-delay (SYS) and adjusting-delay (ADJ) procedures, predicting that intervention effects would be more effective on the SYS procedure with predictable delays. The ADJ procedure did not benefit significantly from intervention, but the SYS procedure, unexpectedly, showed greater impulsive choices following intervention. Experiment 2 tested whether short (5 s) SS intervention delays may have promoted greater impulsivity in the SYS impulsive choice procedure in Experiment 1. Short SS delays in choice and intervention procedures increased impulsive choices in comparison to longer (10 s) delays. Incongruent SS delays in the intervention/choice procedures resulted in negative intervention effects. The results suggest that short SS delays are detrimental to self-control and that specific temporal information generalizes from the intervention to the SYS choice task, but not the ADJ choice task.

In Search of the Preference Reversal Zone.

A preference reversal is observed when a preference for a larger-later (LL) reward over a smaller-sooner (SS) reward reverses as both rewards come closer in time. Preference reversals are common in everyday life and in the laboratory and are often claimed to support hyperbolic delay-discounting models which, in their simplest form, can model reversals with only one free parameter. However, it is not clear if the temporal location of preference reversals can be predicted a priori. Studies testing model predictions have not found support for them, but they overlooked the well-documented effect of reinforcer magnitude on discounting rate. Therefore, we directly tested hyperbolic and exponential model predictions in a pre-registered study by assessing individual discount rates for two reinforcer magnitudes. We then made individualized predictions about pairs of choices between which preference reversals should occur. With 107 participants, we found (1) little evidence that hyperbolic and exponential models could predict the temporal location of preference reversals, (2) some evidence that hyperbolic models had better predictive performance than exponential models, and (3) in contrast to many previous studies, that exponential models generally produced superior fits to the observed data than hyperbolic models.

Delay discounting and neurocognitive correlates among inner city adolescents with and without family history of substance use disorder

Adolescents with a family history (FH+) of substance use disorder (SUD) are at a greater risk for SUD, suggested to be partly due to the transmission of behavioral impulsivity. We used a delay discounting task to compare impulsivity in decision-making and its associated brain functioning among FH+ and FH - minority adolescents. Participants chose between Smaller Sooner (SS) and Larger Later (LL) rewards. The SS was available immediately (Now trials) or in the future (Not-Now trials), allowing for greater differentiation between impulsive decisions. The FH+ group showed greater impatience by responding SS more frequently than the FH - group, only on the Now trials, and even when the relative reward differences (RRD) increased. Surprisingly, there were no differences in brain activity between the groups. Combined, the groups showed greater reward activity during the Now vs. Not-Now trials in medial prefrontal/anterior cingulate, posterior cingulate, precuneus, and inferior frontal gyrus (i.e., an immediacy effect). As the RRD increased activation in the reward network decreased, including the striatum, possibly reflecting easy decision-making. These results indicate that risk for SUD, seen behaviorally among FH+ adolescents, may not yet be associated with discernable brain changes, suggesting that early intervention has the potential to reduce this risk.

Sign effect in adolescents: Within-subject comparison of delay discounting of hypothetical monetary gains and losses.

The purpose of this article is to contribute to the research on the sign effect, steeper discounting of gains compared to losses, by offering results from an experiment using a "double-delay" procedure on adolescents. Twenty-four 14-year-old schoolchildren completed a computer-based test consisting of choices of Smaller-Sooner (SS) and Larger-Later (LL) hypothetical monetary gains and losses. Within-subject comparison and analysis of the aggregated data were conducted. Current results were also examined in light of prior research with adult participants, and variations in behavioral patterns were identified. Although the sign effect appears to be more profound in adolescents compared to adults, the effect of immediacy persists regardless of the sign of the outcome, and zero discounting of losses is often the case, suggesting that the sign effect is driven largely by qualitative differences.

Striatal bases of temporal discounting in early adolescents

Steeper rates of temporal discounting—the degree to which smaller-sooner (SS) rewards are preferred over larger-later (LL) ones—have been associated with impulsive and ill-advised behaviors in adolescence. Yet, the underlying neural systems remain poorly understood. Here we used a well-established temporal discounting paradigm and functional MRI (fMRI) to examine engagement of the striatum—including the caudate, putamen, and ventral striatum (VS)—in early adolescence (13–15 years; N = 27). Analyses provided evidence of enhanced activity in the caudate and VS during impulsive choice. Exploratory analyses revealed that trait impulsivity was associated with heightened putamen activity during impulsive choices. A more nuanced pattern was evident in the cortex, with the dorsolateral prefrontal cortex mirroring the putamen and posterior parietal cortex showing the reverse association. Taken together, these observations provide an important first glimpse at the distributed neural systems underlying economic choice and trait-like individual differences in impulsivity in the early years of adolescence, setting the stage for prospective-longitudinal and intervention research.

Experience Matters: The Effects of Hypothetical versus Experiential Delays and Magnitudes on Impulsive Choice in Delay Discounting Tasks.

Impulsive choice in humans is typically measured using hypothetical delays and rewards. In two experiments, we determined how experiencing the delay and/or the reward affected impulsive choice behavior. Participants chose between two amounts of real or hypothetical candy (M&Ms) after a real or hypothetical delay (5–30 s), where choosing the shorter delay was the impulsive choice. Experiment 1 compared choice behavior on a real-delay, real-reward (RD/RR) task where participants received M&Ms after experiencing the delays versus a real-delay, hypothetical-reward (RD/HR) task where participants accumulated hypothetical M&Ms after experiencing the delays. Experiment 2 compared the RD/HR task and a hypothetical-delay, hypothetical-reward (HD/HR) task where participants accumulated hypothetical M&Ms after hypothetical delays. The results indicated that choices did not differ between real and hypothetical M&Ms (Experiment 1), and participants were less sensitive to delay and more larger-later (LL)-preferring with hypothetical delays compared to real delays (Experiment 2). Experiencing delays to reward may be important for modeling real-world impulsive choices where delays are typically experienced. These novel experiential impulsive choice tasks may improve translational methods for comparison with animal models and may be improved procedures for predicting real-life choice behavior in humans.

Uncommitted Commitment: Behavioral Strategy to Prevent Preference Reversals.

When both smaller-sooner (SS) and larger-later (LL) rewards are temporally distal, individuals frequently prefer the LL. However, because both outcomes become proximal, individuals frequently switch to preferring the SS. These preference reversals are predicted by hyperbolic delay discounting, and may model the essential challenge of self-control. Using smokers, a population known to have high rates of delay discounting, and thus more vulnerable to preference reversals, this pilot study sought to examine soft commitment as a strategy that may prevent preference reversals. Eleven smokers were assigned to an experimental commitment condition, operationalized as 3 weeks of daily commitment trials indicating preference between an SS and LL. Ten smokers were assigned to a control commitment condition. These 3 weeks were followed by 8 days of daily choice trials indicating preference between an impending SS and LL, for both experimental and control conditions. Though no overall difference of preference was observed between groups during the choice trials, hierarchical linear modeling revealed a decrease in preference for the LL over time by the control group (e.g., increasing trend of preference reversals) but no changes by the experimental group. This pilot study provides an initial indication that soft commitment can facilitate choice persistence and prevent preference reversals.

A time-based intervention to treat impulsivity in male and female rats

Time-based interventions have emerged as promising treatments for disorders associated with impulsivity. These interventions can be implemented to test their efficacy in preventing or treating impulsive choice in animal models of diseases related to impulsivity such as drug abuse. Impulsive choice is typically defined as choosing a smaller-sooner (SS) reward over a larger-later (LL) reward when the LL is relatively more optimal. Previous research has shown that these interventions promote LL choices in males and females, but sex differences have not been assessed. Because sex differences can complicate the application of therapies, it is critical to compare the effects of the intervention in males and females. The intervention group received exposure to 10-s and 30-s interval schedules, and the control rats received no delay to reward. Different impulsive choice tasks were used to assess the intervention efficacy across the two experiments. Following the intervention, reductions in impulsive choice were found in male and female rats, but the degree of improvement was inconsistent across sex and task. Bayesian analyses that combined the results revealed robust evidence of an overall intervention effect with the intervention group showing greater self-control, but there was no evidence for the intervention affecting males and females differently. Taken together, these results suggest that time-based interventions are effective tools to treat impulsivity in both males and females and offer promising translational capability to humans.

Past and future preference reversals are predicted by delay discounting in smokers and non-smokers.

Delay discounting, the devaluation of delayed reinforcers, is one defining behavioral economic characteristic of cigarette smokers. Attempts at abstinence by smokers that result in relapse are conceptualized in this framework as preference reversals. Despite preference reversals being predicted by delay discounting models, little research has investigated the association between discount rate and preference reversals. The present study extended this research by examining the relation between discounting and preference reversals. Because previous research indicates that cigarette smokers discount at higher rates than controls and that past and future discounting are symmetrical, the present study assessed the relation between these two processes when hypothetical money was distanced in the past and future, respectively. These assessments of delay discounting and preference reversals were adapted from Yi, Matusiewicz, and Tyson (2016) and examined in 68 smokers and 68 nonsmokers using the crowdsourcing program Amazon Mechanical Turk. Smokers discounted both past and future hypothetical money more steeply than demographically matched controls. Smokers switched preference from the smaller-sooner (SS) to the larger-later (LL) outcome more slowly than nonsmokers, consistent with smokers' steeper delay discounting. For each group, significant positive correlations between past and future discount rates and past and future preference reversals was obtained. The overall pattern of results illustrate symmetry between past and future discounting and preference reversals, respectively and that discount rate is positively associated with the timing of preference reversals. Importantly, the results confirm that cigarette smokers discount more and reverse preference from a SS to a LL reward later than controls. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

An exploratory study of a real-time choice procedure

ABSTRACT In this exploratory study, we expand the research on choice using real outcomes in real-time settings. The object is to refine a method for examining the reinforcing contingencies in discounting, for which real rather than hypothetical settings are necessary. In the experiments, adult human participants chose between a smaller-sooner (SS) and a larger-later (LL) alternative, with an adjusting real delay to LL. We examined the use of points as the outcome and tested conditions concerning amount of outcome and delay. Second, we analyzed how differences in criteria for establishing an Indifference Point (IP) might determine the location of the IP. Finally, we performed a control experiment, introducing a decreasing delay and post-experimental questions, to determine whether the choices were a result of the adjusting delay or by molar considerations. This study gives support to the use of points as reinforcers and delay of seconds in discounting studies on human adults.

Durability and generalizability of time-based intervention effects on impulsive choice in rats

Impulsive choice involves choosing a smaller-sooner (SS) reward over a larger-later (LL) reward. Due to the importance of timing processes in impulsive choice, time-based interventions have been developed to decrease impulsive choice. The present set of experiments assessed the durability and generalizability of time-based interventions. Experiment 1 assessed fixed interval (FI) or variable interval (VI) intervention efficacy over 9 months. The FI intervention decreased impulsive choice, and this effect persisted over time, but the VI intervention effects were only apparent when tested immediately after the intervention. Experiment 2 examined the generalizability of the FI and VI interventions on choice tasks manipulating the SS delay, LL delay, or LL magnitude. The FI intervention decreased sensitivity to delay, promoting LL choices in both delay tasks, but the VI intervention only altered choices when manipulating the SS delay. Experiment 3 further examined the FI intervention effects on tasks that manipulated the LL delay or magnitude immediately following the intervention. The intervention decreased sensitivity to both delay and magnitude. The experiments indicate that the FI intervention is effective at decreasing impulsive choice behavior for an extended period across changing delays and magnitudes, suggesting a relatively broad effect on choice behavior.