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

Social effort discounting reveals domain-general and social-specific motivation components

BACKGROUND

Social motivation is crucial for healthy interpersonal connections and is impaired in a subset of the general population and across many psychiatric disorders. However, compared to nonsocial (e.g., monetary) motivation, social motivation has been understudied in quantitative behavioral work, especially regarding willingness to exert social effort. We developed a novel social effort discounting task, paired with a monetary task to examine motivational specificity. We expected social task performance would relate to general motivation also show selective relationships with self-reported avoidance tendencies and with sociality.

METHODS

An analyzed sample of 397 participants performed the social and nonsocial effort discounting task online, along with self-report measures of various aspects of motivation and psychiatric symptomatology.

RESULTS

Social and nonsocial task motivation correlated strongly (rho=0.71 p<0.001). Both social and nonsocial task motivation related similarly to self-reported general motivation (social ß=0.16; nonsocial ß=0.13) and to self-reported approach motivation (social ß=0.14; nonsocial ß=0.11), with this common effect captured by a significant main effect across social and nonsocial conditions. Significant condition interaction effects supported a selective relationship of social task motivation with self-reported sociality and also with avoidance motivation.

CONCLUSIONS

Our novel social effort discounting task revealed both domain-general and social-specific components of motivation. In combination with other measures, this approach can facilitate further investigation of common and dissociable neurobehavioral mechanisms, in order to better characterize normative and pathological variation and develop personalized interventions targeting specific contributors to social impairment.

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.

Reduced access to reinforcement drives delay discounting during experienced delays

Rewards lose value as a function of delay. Previous studies suggest that delays have a bigger effect on reward value when people must wait during the delay. However, whether delays involve waiting or postponing has often been confounded with whether choices are about hypothetical or real rewards. The current study characterized the effects of waiting and postponing in hypothetical and experiential choice contexts separately. In Experiment 1 we observed steeper delay discounting for waiting than for postponing in choices about both hypothetical money and about experienced computer game points. Two factors potentially contributing to steeper discounting in choices about waiting are reduced access to other rewards and direct costs of waiting. In Experiment 2, we adapted the experiential delay-discounting task to manipulate each factor separately. Reduced access to other reinforcers had a bigger effect on delay discounting than direct costs of waiting. These results underscore the importance of considering the unique influence of waiting and associated opportunity costs in both basic delay-discounting research and in applied contexts.

The sooner the better: clinical and neural correlates of impulsive choice in Tourette disorder

Reward sensitivity has been suggested as one of the central pathophysiological mechanisms in Tourette disorder. However, the subjective valuation of a reward by introduction of delay has received little attention in Tourette disorder, even though it has been suggested as a trans-diagnostic feature of numerous neuropsychiatric disorders. We aimed to assess delay discounting in Tourette disorder and to identify its brain functional correlates. We evaluated delayed discounting and its brain functional correlates in a large group of 54 Tourette disorder patients and 31 healthy controls using a data-driven approach. We identified a subgroup of 29 patients with steeper reward discounting, characterised by a higher burden of impulse-control disorders and a higher level of general impulsivity compared to patients with normal behavioural performance or to controls. Reward discounting was underpinned by resting-state activity of a network comprising the orbito-frontal, cingulate, pre-supplementary motor area, temporal and insular cortices, as well as ventral striatum and hippocampus. Within this network, (i) lower connectivity of pre-supplementary motor area with ventral striatum predicted a higher impulsivity and a steeper reward discounting and (ii) a greater connectivity of pre-supplementary motor area with anterior insular cortex predicted steeper reward discounting and more severe tics. Overall, our results highlight the heterogeneity of the delayed reward processing in Tourette disorder, with steeper reward discounting being a marker of burden in impulsivity and impulse control disorders, and the pre-supplementary motor area being a hub region for the delay discounting, impulsivity and tic severity.

The relationship between dietary fat intake, impulsive choice, and metabolic health

Unhealthful foods are convenient, ubiquitous, and inexpensive. Overconsumption of unhealthful foods can result in disease states such as obesity and Type 2 diabetes. In addition to the physiological consequences of unhealthful foods, research in rats has shown that diets high in processed fat and sugar induce impulsive choice behavior. Research in humans has demonstrated a link between metabolic health and impulsive choice, but most investigations have not included diet. We investigated how dietary fat intake interacts with body fat percentage, fasting glucose, insulin response, and systemic inflammation levels to predict impulsive choices in humans. Participants were split into either Control (<35% calories from fat) or High-Fat (≥40% calories from fat) groups based on self-reported dietary intake, completed an impulsive choice task, and underwent testing to determine their body fat, glucose, insulin response, and inflammation levels. High-fat diets were not predictive of impulsive choices, but added sugar was predictive. Body fat percentage was associated with impulsive choices only in the group who reported consuming high-fat diets. In addition, fasting glucose was associated with impulsive choices in the control group. Therefore, metabolic health and dietary fat intake interacted to predict impulsive choices. These findings indicate that knowledge of dietary patterns coupled with metabolic health markers may help us better understand impulsive choices, thereby improving our ability to target individuals who could benefit from interventions to reduce impulsive choice behavior, with the goal of promoting more self-controlled food choices.

Temporal discounting in adolescents and adults with Tourette syndrome

Tourette syndrome is a neurodevelopmental disorder associated with hyperactivity in dopaminergic networks. Dopaminergic hyperactivity in the basal ganglia has previously been linked to increased sensitivity to positive reinforcement and increases in choice impulsivity. In this study, we examine whether this extends to changes in temporal discounting, where impulsivity is operationalized as an increased preference for smaller-but-sooner over larger-but-later rewards. We assessed intertemporal choice in two studies including nineteen adolescents (age: mean[sd] = 14.21[±2.37], 13 male subjects) and twenty-five adult patients (age: mean[sd] = 29.88 [±9.03]; 19 male subjects) with Tourette syndrome and healthy age- and education matched controls. Computational modeling using exponential and hyperbolic discounting models via hierarchical Bayesian parameter estimation revealed reduced temporal discounting in adolescent patients, and no evidence for differences in adult patients. Results are discussed with respect to neural models of temporal discounting, dopaminergic alterations in Tourette syndrome and the developmental trajectory of temporal discounting. Specifically, adolescents might show attenuated discounting due to improved inhibitory functions that also affect choice impulsivity and/or the developmental trajectory of executive control functions. Future studies would benefit from a longitudinal approach to further elucidate the developmental trajectory of these effects.

Decision making in substance use disorder patients: Reliability, convergent validity and sensitivity to change of a new behavioral measure

OBJECTIVE

The Iowa Gambling Task (IGT) and the Delay Discounting Test (DDT) are two of the most widely used decision-making tests within the field of addiction research. The IGT creates a context of uncertainty where immediate rewards or long-term benefits are chosen, whilst the DDT measures the change in value of a reward as the time taken to obtain it increases. The objective of this study was to analyze the psychometric properties of a new task: Deciding about your health (DAYH), which integrates both components.

METHOD

Longitudinal observational study. The sample was composed of 97 patients being treated for cocaine use disorder. The DAYH, IGT, DDT and other instruments for measuring dependence severity were administered. Relapse was evaluated within 3 and 6 months after the baseline assessment.

RESULTS

Reliability was indicated by an intraclass correlation coefficient (r) of. 80. DAYH scores showed significant relationships with IGT (r = -.237; p <.05), although not with DDT (r =.048) scores. A relationship was also found between DAYH and dependency severity (r = -.213; p <.05) and craving (r = -.231; p <.05). The DAYH scores showed sensitivity to change, and the capacity to predict relapse.

CONCLUSIONS

These findings indicate the utility of DAYH for exploring decision-making in patients with substance use disorders. The relationships with IGT and DDT also indicate the need to further investigate how decisions are made in various contexts of choice.