Temporal Discounting

Global warming mitigation calculations require consistent procedures for handling time in order to compare 'permanent' gains from energy-sector mitigation options with 'impermanent' gains from many forest-sector options. A critical part of carbon accounting methodologies such as those based on 'ton-years' (the product of the number of tons of carbon times the number of years that each ton is held out of the atmosphere) is definition of a time horizon, or the time period over which carbon impacts and benefits are considered. Here a case is made for using a time horizon of 100 years. This choice avoids distortions created by much longer time horizons that would lead to decisions inconsistent with societal behavior in other spheres; it also avoids a rapid increase in the implied value of time if horizons shorter than 100 years are used. Selection of a time horizon affects decisions on financial mechanisms and carbon credit. Simple adaptations can allow a time horizon to be specified and used to calculate mitigation benefits and at the same time reserve a given percentage of weight in decision making for generations beyond the end of the time horizon. The choice of a time horizon will heavily influence whether mitigation options such as avoided deforestation are considered viable.

L’operazione economica di discounting ci serve, come abbiamo visto, per attualizzare le grandezze
economiche future. Nel momento in cui in un paese si cerca di attuare una politica economica è
inevitabile che si cerchi di comprendere quale possa essere l’effetto della stessa sulle generazioni
future. Ed è così anche per le questioni di gestione delle risorse e, come si nota nella lettura della
Stern Review, anche nel caso del cambiamento climatico. Queste politiche sono anche chiamate
scelte intertemporali, proprio a sottolineare l’importanza del tempo e delle generazioni che
verranno. Ma non solo. Il discounting è un’operazione molto complessa che nasce
dall’aggregazione di alcuni parametri economici e tiene conto di una serie di fattori. Vediamone
brevemente la formula.
.

Streszczenie Celem projektu było skonstruowanie Inwentarza dyskontowania, który umożliwiałby pomiar różnic indywidualnych w zakresie nasilenia dyskontowania odroczonego, praw-dopodobieństwa, wysiłku i społecznego. Pomiar nasilenia dyskontowania jest istotny, ponieważ wysokie nasilenie dyskontowania prowadzi do nieadaptacyjnej behawioralnej impulsywności. Wygenerowano ponad 400 pozycji obejmujących cztery rodzaje dys-kontowania. Przeprowadzono badanie, w którym udział wzięły 2843 osoby. Następ-nie wykonano szereg analiz psychometrycznych. Eksploracyjna analiza czynnikowa wykazała czteroczynnikową strukturę uzyskanych danych, odpowiadających czterem rodzajom dyskontowania. Rezultaty konfirmacyjnej analizy czynnikowej wskazują na dobre dopasowanie do danych struktury czteroczynnikowej. Ostateczna, 48-elemento-wa wersja narzędzia ma zadowalające właściwości psychometryczne, w tym zgodność wewnętrzną i stabilność bezwzględną mierzoną metodą test–retest. Zakończona suk-cesem konstrukcja narzędzia wspiera założenie, że dyskontowanie może być traktowa-ne jako cecha osobowości. Abstract The aim of the paper is to present the process of construction and psychometric properties of the Discounting Inventory that would allow the assessment of individual differences in delay, probabilistic, effort, and social discounting rates. The assessment of the rate of discounting is important, because high rates of discounting lead to disa-daptive behavioral impulsivity. At the beginning, over 400 items covering four types of discounting were generated. The psychometric study (N = 2843) and factor analysis of data allowed to distinguish four traits. Confirmatory Factor Analysis was used to confirm the factor structure of the data from the Exploratory Factor Analysis. It was shown, that the four-factor structure had the best fit to the data. The final 48-item version of the inventory has satisfactory psychometric characteristics, including Cronbach's alpha and test-retest stability. The successful construction of a universal Discounting Inventory supports the hypothesis that the discounting rate can be regarded as an individual personality trait.

Animals often aid others without gaining any immediate benefits. Although these acts seem to reduce the donor's fitness, they are only apparently altruistic. Donors typically help because they or their kin receive future benefits or avoid costly punishment. Reciprocal altruism – alternating the roles of donor and recipient – has been a well-studied form of cooperation among non-kin because of its intuitive appeal in explaining human cooperation. Despite immense theoretical interest, little empirical evidence substantiates the biological importance of reciprocal altruism in non-human animals. We propose that this is because psychological mechanisms constrain its application in cooperative contexts. In particular, we contend that cognitive limitations such as temporal discounting, numerical discrimination and memory make reciprocity difficult for animals.

A standard way to create social dilemmas in the experimental laboratory is the prisoner dilemma game. In this environment, players are given an endowment of tokens and faced with a choice between cooperation and defection. In the present study a prisoner's dilemma game was administrated to individuals (N = 280), along with measures of Dark Triad and impulsivity. Dark Triad variables were found to predict the likelihood of defection in the prisoner's dilemma. Specifically, high levels of psychop-athy coupled with high impulsivity may better describe a person who repeatedly attempts to extract defection. Defection was also more likely for individuals who scored higher on the Machiavellianism domain. Although Machiavellianism is also linked to higher defection, it has no association with impulsivity, but, rather, is associated with strategy and long-term planning. Interestingly, individuals high in narcissism with their entitlement and over-confidence had no significant effect on defection in such a game. Overall, the study suggests that two dark personality traits can be a significant predictor of behaviour in the prisoner's dilemma.

The tendency to make unhealthy choices is hypothesized to be related to an individual's temporal discount rate, the theoretical rate at which they devalue delayed rewards. Furthermore, a particular form of temporal discounting, hyperbolic discounting, has been proposed to explain why unhealthy behavior can occur despite healthy intentions. We examine these two hypotheses in turn. We first systematically review studies which investigate whether discount rates can predict unhealthy behavior. These studies reveal that high discount rates for money (and in some instances food or drug rewards) are associated with several unhealthy behaviors and markers of health status, establishing discounting as a promising predictive measure. We secondly examine whether intention-incongruent unhealthy actions are consistent with hyperbolic discounting. We conclude that intention-incongruent actions are often triggered by environmental cues or changes in motivational state, whose effects are not parameterized by hyperbolic discounting. We propose a framework for understanding these state-based effects in terms of the interplay of two distinct reinforcement learning mechanisms: a " model-based " (or goal-directed) system and a " model-free " (or habitual) system. Under this framework, while discounting of delayed health may contribute to the initiation of unhealthy behavior, with repetition, many unhealthy behaviors become habitual; if health goals then change, habitual behavior can still arise in response to environmental cues. We propose that the burgeoning development of computational models of these processes will permit further identification of health decision-making phenotypes.

Most definitions of sustainability imply that a system is to be maintained at a certain level, held within certain limits, into the indefinite future. Sustainability denies run-away growth, but it also avoids any decline or destruction. This sustainability path is hard to reconcile with the renewal cycle that can be observed in many natural systems developing according to their intrinsic mechanisms and in social systems responding to internal and external pressures. Systems are parts of hierarchies where systems of higher levels are made up of subsystems from lower levels. Renewal in components is an important factor of adaptation and evolution. If a system is sustained for too long, it borrows from the sustainability of a supersystem and rests upon lack of sustainability in subsystems. Therefore by sustaining certain systems beyond their renewal cycle, we decrease the sustainability of larger, higherlevel systems. For example, Schumpeter's theory of creative destruction posits that in a capitalist economy, the collapse and renewal of firms and industries is necessary to sustain the vitality of the larger economic system. However, if the capitalist economic system relies on endless growth, then sustaining it for too long will inevitably borrow from the sustainability of the global ecosystem. This could prove catastrophic for humans and other species. To reconcile sustainability with hierarchy theory, we must decide which hierarchical level in a system we want to sustain indefinitely, and accept that lower level subsystems must have shorter life spans. In economic analysis, inter-temporal discount rates essentially tell us how long we should care about sustaining any given system.

Impatience for reward is a facet of many psychiatric disorders. We draw attention to a growing literature finding greater discounting of delayed reward, an important aspect of impatience, across a range of psychiatric disorders. We propose these findings are best understood by considering the goals and motivation for discounting future reward. We characterize these as arising from either the opportunity costs of waiting or the uncertainty associated with delayed reward. We link specific instances of higher discounting in psychiatric disorder to heightened subjective estimates of either of these factors. We propose these costs are learned and represented based either on a flexible cognitive model of the world, an accumulation of previous experience, or through evolutionary specification. Any of these can be considered suboptimal for the individual if the resulting behavior results in impairments in personal and social functioning and/or in distress. By considering the neurochemical and neuroanatomical implementation of these processes, we illustrate how this approach can in principle unite social, psychological and biological conceptions of impulsive choice.

This white paper explores ways to counter temporal discounting and to promote long-term thinking by engaging emotions. From the enhancement of emotional regulation to the activation of transcendent emotions, this paper seeks to provide an initial roadmap for the optimal integration of emotions into the temporal decision-making process. Transgenerational empathy and awe are specifically identified as emotions that can orient people toward a broader temporal perspective.

Actors in competitive environments are bound to decide and act under conditions of uncertainty because they rarely have accurate foreknowledge of how their opponents will respond and when they will respond. Just as a competitor makes a move to improve their standing on a given variable relative to a target competitor, she should expect the latter to counteract with an iterative lagged asymmetric response, that is, with a sequence of countermoves (iteration) that is very different in kind from its trigger (asymmetry) and that will be launched at some unknown point in the future (time lag). The paper explicates the broad relevance of the newly proposed concept of " iterative lagged asymmetric responses " to the social study of temporality and to fields as diverse as intelligence and counterintelligence studies, strategic management, futures studies, military theory, and long-range planning. By bringing out in the foreground and substantiating the observation that competitive environments place a strategic premium on surprise, the concept of iterative lagged asymmetric responses makes a contribution to the never-ending and many-pronged debate about the extent to which the future can be predicted.
DOI: https://doi.org/10.1177/0961463X17752652

In this investigation, we test whether temporal discounting is domain-specific (i.e., compared to other people, can an individual have a relatively high discount rate for one type of reward but a relatively low discount rate for another?), and we examine whether individual differences in the types of rewards one finds tempting explain domain-specificity in discount rates. Adults discounted delayed rewards they found particularly tempting (defined as the visceral attraction to and enjoyment of a reward) more steeply than did adults who did not find the rewards as tempting, contrary to what might be expected from the magnitude effect. Furthermore, we found significant group by domain interactions (e.g., chip lovers who do not like beer have relatively high discount rates for chips and relatively low discount rates for beer, whereas beer lovers who do not like chips showed the opposite pattern). These results suggest that domain-specificity in temptation partially accounts for corresponding domain-specificity in temporal discounting.

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The concept of emotion regulation states that individuals with poorly regulated emotions often engage in maladaptive behaviours to escape from or down-regulate their emotions, creating risk for a range of maladaptive behaviors. One such behavior may be higher delay discounting, which reflects greater impulsivity. The goal of the present study was therefore to examine the relationship between emotion regulation strategies and deficits with discounting of delayed monetary outcomes (N = 458). Results showed that general emotion dysregulation was associated with greater delay discounting. Also, negative affect was directly related to greater delay discounting. However, specific regulation deficits, including deficits in emotional clarity, emotional awareness, acceptance of emotions, ability to engage in goal directed behaviors when distressed, impulse control, and access to effective regulation strategies, were associated with greater delay discounting above and beyond variance contributed by negative affectivity. Next, people who showed greater delay discounting reported significantly more use of suppression as a maladaptive emotion regulation strategy, compared to people who show shallow delay discounting. Finally, gender was related to a number of key study variables, with women reporting greater negative affect, slower delay discounting, and greater general difficulties with emotion regulation, less access to regulation strategies, and less ability to engage in goal directed behavior when upset, than men.

Patients with bipolar disorder (BD) and schizophrenia (SZ) often show decision-making deficits in everyday circumstances. A failure to appropriately weigh immediate versus future consequences of choices may contribute to these deficits. We used the delay discounting task in individuals with BD or SZ to investigate their temporal decision making. Twenty-two individuals with BD, 21 individuals with SZ, and 30 healthy individuals completed the delay discounting task along with neuropsychological measures of working memory and cognitive function. Both BD and SZ groups discounted delayed rewards more steeply than did the healthy group even after controlling for current substance use, age, gender, and employment. Hierarchical multiple regression analyses showed that discounting rate was associated with both diagnostic group and working memory or intelligence scores. In each group, working memory or intelligence scores negatively correlated with discounting rate. The results suggest that (a) both BD and SZ groups value smaller, immediate rewards more than larger, delayed rewards compared with the healthy group and (b) working memory or intelligence is related to temporal decision making in individuals with BD or SZ as well as in healthy individuals.

Clinic-referred teens (ages 12–19) with ADHD and ODD (N = 101) were compared to community control (CC) teens, equated for age and sex, (N = 39) on a variety of psychological tasks assessing executive functioning (EF), temporal reward discounting, and time estimation and reproduction. A factor analysis reduced the EF measures to three dimensions, representing CPT Inattention, Working Memory, and CPT Inhibition. Results indicated that the ADHD group had significantly more CPT Inattention than the CC group. No differences were found for Working Memory or CPT Inhibition. The ADHD group displayed significantly greater temporal discounting of delayed hypothetical monetary rewards relative to immediate ones and manifested more impaired time reproduction, but not time estimation, than did the CC group. Main effects for level of IQ were found only on the Working Memory factor and largely did not interact with the group factor otherwise. The group differences in CPT Inattention, temporal discounting, and time reproduction were not a function of level of comorbid oppositional defiant disorder, delinquency, or anxiety–depression. Results are reasonably consistent with past research on EF and sense of time in children with ADHD and extend these findings to the adolescent age group. Problems with working memory and CPT inhibition found in prior studies of children with ADHD, however, were not evident here, perhaps owing to age-related improvements or insufficient task difficulty.

We review behavioral-and neuroeconomic research that identifies temporal discounting as an important component in the development and maintenance of drug addiction. First we review behavioral economic research that explains and documents the contribution of temporal discounting to addiction. This is followed with recent insights from neuroeconomics that may provide an explanation of why drug dependent individuals discount the future. Specifically, neuroeconomics has identified two competing neural systems that are related to temporal discounting using brainimaging techniques that examine the relative activation of different brain regions for temporal discounting. According to the competing neural systems account, choices for delayed outcomes are related to the prefrontal cortex (i.e., the "executive system") and choices for immediate outcomes are related to the limbic brain regions (i.e., the "impulsive system"). Temporal discounting provides a useful framework for future imaging research, and suggests a novel approach to designing effective drug dependence prevention and treatment programs.

Procrastination is common in the collegiate sphere. However, it is often stigmatized as causing college students to be unsuccessful. Most students have been told not to procrastinate, but they continue to do so, implying that student procrastination will not stop. This article points to discontinuities between emerging research in three fields - active and passive procrastination, temporal discounting, and project management – and the standard advice given to students. This article points to a more nuanced view of student procrastination and the mechanisms to encourage their productivity.

Previous research demonstrates that stress is a precipitant of greater delay discounting, which reflects greater behavioral impulsivity. However, the underlying factors that explain this relationship are unclear. The concept of emotion regulation states that individuals with poorly regulated emotions often engage in maladaptive behaviors to escape from or down-regulate their emotions. One such behavior may be greater delay discounting. Thus, the purpose of this study was to examine whether difficulties in emotion regulation would mediate the association between stress and delay discounting. The sample consisted of 418 adults. In addition to the traditional discounting measure with pairs of hypothetical choices between immediate and delayed monetary outcomes, the Perceived Stress Scale and Difficulties in Emotion Regulation Scale were used to collect data. Results showed that experience of stress was related to individuals' poorer capability of emotion regulation, which in turn, was related to higher delay discounting rate. Additionally, higher stress level was directly related to greater delay discounting. Furthermore, difficulties in emotion regulation have a significant mediator role in the relationship between stress and delay discounting. It is argued that individuals with high levels of stress become prone to impulsive behavior like greater delay discounting via emotional dysregulation.

In 3 studies, participants made choices between hypothetical financial, environmental, and health gains and losses that took effect either immediately or with a delay of 1 or 10 years. In all 3 domains, choices indicated that gains were discounted more than losses. There were no significant differences in the discounting of monetary and environmental outcomes, but health gains were discounted more and health losses were discounted less than gains or losses in the other 2 domains. Correlations between implicit discount rates for these different choices suggest that discount rates are influenced more by the valence of outcomes (gains vs. losses) than by domain (money, environment, or health). Overall, results indicate that when controlling as many factors as possible, at short to medium delays, environmental outcomes are discounted in a similar way to financial outcomes, which is good news for researchers and policy makers alike.

During intertemporal choice, humans tend to prefer small-sooner rewards over larger-delayed rewards, reflecting temporal discounting (TD) of delayed outcomes. Functional neuroimaging (fMRI) evidence has implicated the insular cortex in time-sensitive decisions, yet it is not clear whether activity in this brain region is crucial for, or merely associated with, TD behavior. Here, patients with damage to the insula (Insular patients), control patients with lesions outside the insula, and healthy individuals chose between smaller-sooner and larger-later monetary rewards. Insular patients were less sensitive to sooner rewards than were the control groups, exhibiting reduced TD. A Voxel-based Lesion-Symptom Mapping (VLSM) analysis confirmed a statistically significant association between insular damage and reduced TD. These results indicate that the insular cortex is crucial for intertemporal choice. We suggest that he insula may be necessary to anticipate the bodily/emotional effects of receiving rewards at different delays, influencing the computation of their incentive value. Devoid of such input, insular patients' choices would be governed by a heuristic of quantity, allowing patients to wait for larger options.

Many proposed activities for mitigating global warming in the land-use change and forestry (LUCF) sector differ from measures to avoid fossil fuel emissions because carbon (C) may be held out of the atmosphere only temporarily. In addition, the timing of the effects is usually different. Many LUCF activities alter C fluxes to and from the atmosphere several decades into the future, whereas fossil fuel emissions avoidance has immediate effects. Non-CO 2 greenhouse gases (GHGs), which are an important part of emissions from deforestation in low-latitude regions, also pose complications for comparisons between fossil fuel and LUCF, since the mechanism generally used to compare these gases (global warming potentials) assumes simultaneous emissions. A common numeraire is needed to express global warming mitigation benefits of different kinds of projects, such as fossil fuel emissions reduction, C sequestration in forest plantations, avoided deforestation by creating protected areas and through policy changes to slow rates of land-use changes such as clearing. Megagram (Mg)-year (also known as 'ton-year') accounting provides a mechanism for expressing the benefits of activities such as these on a consistent basis. One can calculate the atmospheric load of each GHG that will be present in each year, expressed as C in the form of CO 2 and its instantaneous impact equivalent contributed by other gases. The atmospheric load of CO 2 -equivalent C present over a time horizon is a possible indicator of the climatic impact of the emission that placed this load in the atmosphere. Conversely, this index also provides a measure of the benefit of not producing the emission. One accounting method compares sequestered CO 2 in trees with the CO 2 that would be in the atmosphere had the sequestration project not been undertaken, while another method (used in this paper) compares the atmospheric load of C (or equivalent in non-CO 2 GHGs) in both project and no-project scenarios. Time preference, expressed by means of a discount rate on C, can be applied to Mg-year equivalence calculations to allow societal decisions regarding the value of time to be integrated into the system for calculating global warming impacts and benefits. Giving a high value to time, either by raising the discount rate or by shortening the time horizon, increases the value attributed to temporary sequestration (such as many forest plantation projects). A high value for time also favors mitigation measures that have rapid effects (such as slowing deforestation rates) as compared to measures that only affect emissions years in the future (such as creating protected areas in countries with large areas of remaining forest). Decisions on temporal issues will guide mitigation efforts towards options that may or may not be desirable on the basis of social and environmental effects in spheres other than global warming. How sustainable development criteria are incorporated into the approval and crediting systems for activities under the Kyoto Protocol will determine the overall environmental and social impacts of pending decisions on temporal issues.

Standard theories of decision-making involving delayed outcomes predict that people should defer a punishment, whilst advancing a reward. In some cases, such as pain, people seem to prefer to expedite punishment, implying that its anticipation carries a cost, often conceptualized as 'dread'. Despite empirical support for the existence of dread, whether and how it depends on prospective delay is unknown. Furthermore, it is unclear whether dread represents a stable component of value, or is modulated by biases such as framing effects. Here, we examine choices made between different numbers of painful shocks to be delivered faithfully at different time points up to 15 minutes in the future, as well as choices between hypothetical painful dental appointments at time points of up to approximately eight months in the future, to test alternative models for how future pain is disvalued. We show that future pain initially becomes increasingly aversive with increasing delay, but does so at a decreasing rate. This is consistent with a value model in which moment-by-moment dread increases up to the time of expected pain, such that dread becomes equivalent to the discounted expectation of pain. For a minority of individuals pain has maximum negative value at intermediate delay, suggesting that the dread function may itself be prospectively discounted in time. Framing an outcome as relief reduces the overall preference to expedite pain, which can be parameterized by reducing the rate of the dread-discounting function. Our data support an account of disvaluation for primary punishments such as pain, which differs fundamentally from existing models applied to financial punishments, in which dread exerts a powerful but time-dependent influence over choice.

As social animals, we regularly act in the interest of others by making decisions on their behalf. These decisions can take the form of choices between smaller short-term rewards and larger long-term rewards, and can be effectively indexed by temporal discounting (TD). In a TD paradigm, a reward loses subjective value with increasing delay presumably because it becomes more difficult to simulate how much the recipient (e.g., future self) will value it. If this is the case, then the value of delayed rewards should be discounted even more steeply when we are choosing for someone whose feelings we do not readily simulate, such as socially distant strangers. Second, the ability to simulate shows individual differences and is indexed by trait empathy. We hypothesized that individuals high in trait empathy will more readily simulate, and hence discount less steeply for distant others, compared to those who are low on trait empathy. To test these predictions, we asked 63 participants from the general population to perform a TD task from the perspectives of close and distant others, as well as their own. People were found to discount less steeply for themselves, and the steepness of TD increased with increasing distance from self. Additionally, individuals who scored high in trait empathy were found to discount less steeply for distant others compared to those who scored low. These findings confirm the role of empathy in determining how we choose rewards for others.

Studies have found that a variety of drug dependent groups discount delayed rewards more than matched-controls. This study compared delay discounting for a hypothetical $1000 reward among dependent marijuana users, former dependent marijuana users, and matched-controls. Discounting of marijuana was also assessed in the currently marijuana-dependent group. No significant difference in discounting was detected among the groups, however currently dependent users showed a trend to discount money more than the other two groups. Within the dependent marijuana group, marijuana was discounted more than money, and discounting for money and marijuana were significantly and positively correlated. Regression analyses indicated that delay discounting was more closely associated with tobacco use than marijuana use. A variety of questionnaires were also administered, including impulsivity questionnaires. Dependent marijuana users scored as significantly more impulsive on the Impulsiveness subscale of the Eysenck Impulsiveness-Venturesomeness-Empathy questionnaire than controls. However, the three groups did not significantly differ on several other personality questionnaires including the Barratt Impulsivity Scale-11. The Stanford Time Perception Inventory Present-Fatalistic subscale was positively correlated with money and marijuana discounting, indicating that a greater sense of powerlessness over the future is related to greater delay discounting. Results suggest that current marijuana dependence may be associated with a trend

Many aspects of the calculation of the impacts of greenhouse gas (GHG) emissions and the costs and benefits of possible response options are highly sensitive to the way in which time preference is incorporated into the computations. The Intergovernmental Panel on Climate Change (IPCC) used global warming potentials (GWPs) to standardize inputs of different gases with differing radiative forcings and atmospheric lifetimes; in the results emphasized by the IPCC's Second Assessment Report, a 100-year time horizon and no discounting is used, and this has been adopted by the Kyoto Protocol for use in the first commitment period (2008)(2009)(2010)(2011)(2012). Here an alternative unified index is proposed that assigns explicit weights to the interests of different generations. In contrast to discounting (including the zero discount rate used by the IPCC), the generationally weighted index forces policy makers to face the moral assumptions that underlie their choices related to global warming. : S 0 9 2 1 -8 0 0 9 ( 0 2 ) 0 0 0 0 4 -6 P.M. Fearnside / Ecological Economics 41 (2002) 21-31

Background: Unhealthy behaviors (eg, poor food choices) contribute to obesity and numerous negative health outcomes, including multiple types of cancer and cardiovascular and metabolic diseases. To promote healthy food choice, diet interventions should build on the dual-system model to target the regulation and reward mechanisms that guide eating behavior. Episodic future thinking (EFT) has been shown to strengthen regulation mechanisms by reducing unhealthy food choice and temporal discounting (TD), a process of placing greater value on smaller immediate rewards over larger future rewards. However, these interventions do not target the reward mechanisms that could support healthy eating and strengthen the impact of EFT-anchored programs. Increasing positive affect (PosA) related to healthy food choices may target reward mechanisms by enhancing the rewarding effects of healthy eating. An intervention that increases self-regulation regarding unhealthy foods and the reward value of healthy foods will likely have a greater impact on eating behavior compared with interventions focused on either process alone.

Economic models of addiction typically posit intertemporal dependencies in the consumption of addictive goods, although the models differ regarding the structure of the dependencies. Addictions are often associated with multiple attempts to quit, usually successfully for short periods of time, accompanied by eventual relapse. This standard life course of addiction illustrates the role that attitudes to risk over time may play in explaining addictive behaviour. While researchers have paid attention to the atemporal risk attitudes of addicts, no prior research has investigated the intertemporal risk attitudes of addicts. Yet measures of risk attitudes at a point in time logically need have no relation at all with risk attitudes over time. Focusing on smoking behaviour, we undertake a natural first step of comparing experimentally elicited intertemporal risk preferences, along with atemporal risk preferences and time preferences, among cohorts of people who have not been addicted, people who are current addicts, and people who are former addicts. From the resulting data we estimate a structural model of intertemporal risk preferences jointly with a rank-dependent utility model of atemporal risk and a quasi-hyperbolic model of time preferences. The intertemporal risk preferences of our sample exhibit significant heterogeneity and, contrary to the assumption employed by standard economic models of addiction, smokers do not exhibit intertemporal risk seeking behaviour. Instead, our sample is characterised by high levels of intertemporal risk aversion which varies by smoking intensity and smoking severity in men, but not in women. Our results highlight the role that intertemporal risk attitudes, together with atemporal risk attitudes and discounting behaviour, play in the aetiology of addiction.

Two algorithms are commonly applied in computerized temporal discounting procedures (Decreasing Adjustment and Double-Limit Algorithms); however, the degree to which the two algorithms produce similar patterns of discounting is unknown. The present experiment compared the two common algorithms across sign (gains and losses) and magnitude ($10 and $1000) conditions. Twenty participants made choices between larger later and smaller sooner alternatives that were presented by each of the algorithms in separate conditions. Strong correlations were found between the two measures; however, the Decreasing Adjustment Algorithm tended to produce lower indifference points and higher rates of discounting than the Double-Limit Algorithm. Both algorithms found significant magnitude effects. Less consistent results were found when comparing the two algorithms across sign. The present results suggest that researchers should apply caution when making comparisons between outcomes of delay discounting studies that have used the two different algorithms. However, the interpretation of findings from individual studies is probably not strongly affected by the use of different computer algorithms.

As social animals, we regularly act in the interest of others by making decisions on their behalf. These decisions can take the form of choices between smaller short-term rewards and larger long-term rewards, and can be effectively indexed by temporal discounting (TD). In a TD paradigm, a reward loses subjective value with increasing delay presumably because it becomes more difficult to simulate how much the recipient (e.g., future self) will value it. If this is the case, then the value of delayed rewards should be discounted even more steeply when we are choosing for someone whose feelings we do not readily simulate, such as socially distant strangers. Second, the ability to simulate shows individual differences and is indexed by trait empathy. We hypothesized that individuals high in trait empathy will more readily simulate, and hence discount less steeply for distant others, compared to those who are low on trait empathy. To test these predictions, we asked 63 participants from the general population to perform a TD task from the perspectives of close and distant others, as well as their own. People were found to discount less steeply for themselves, and the steepness of TD increased with increasing distance from self. Additionally, individuals who scored high in trait empathy were found to discount less steeply for distant others compared to those who scored low. These findings confirm the role of empathy in determining how we choose rewards for others.

Temporal discounting (TD), the preference for earlier, smaller rewards over delayed, larger rewards, is a pervasive phenomenon that covaries with Big Five personality traits and Intelligence (IQ). This study provides novel insight by identifying correlates for IQ and Extraversion in the neural representation of TD preferences. An intertemporal choice task was employed, where offers were sequentially presented, distinguishing between one evaluation phase (first offer is presented) and one comparison phase (second offer is presented and values are compared). IQ correlated with responses of caudate nucleus to the subjective values of the offers, suggesting a role of cognitive abilities in modulating reward responses. Extraversion correlated with the strength of functional connectivity of a reward evaluation network centered on ventromedial prefrontal cortex.

How does the anticipated connectedness between one’s current and future identity help explain impatience in intertemporal preferences? The less consumers are closely connected psychologically to their future selves, the less willing they will be to forgo immediate benefits in order to ensure larger deferred benefits to be received by that future self. When consumers’ measured or manipulated sense of continuity with their future selves is lower, they accept smaller-sooner rewards, wait less in order to save money on a purchase, require a larger premium to delay receiving a gift card, and have lower long-term discount rates.

Humans and other animals often favour immediate gratification over long-term gain. Primates, including humans, appear more willing to wait for rewards than other animals, such as rats or pigeons. Another group displaying impressive patience are the corvids, which possess large brains and show sophisticated cognitive abilities. Here, we assess intertemporal choice in one corvid species, the Western scrub-jay (Aphelocoma californica). These birds cache food for future consumption and respond flexibly to future needs. Cache-theft and cache-degradation are time-dependent processes in scrub-jay ecology that might necessitate sensitivity to delays between caching and retrieval. We adopt a caching paradigm with delays of up to 49 h. Across two experiments we find no evidence of a preference for earlier recovery. We highlight the possibility that, although scrub-jays can discriminate between the present and the future, they may not understand how far into the future an event will occur.

Why do movements take a characteristic amount of time, and why do diseases that affect the reward system alter control of movements? Suppose that purpose of any movement is to position our body in a more rewarding state. People and other animals discount future reward as a hyperbolic function of time. Here, we show that across populations of people and monkeys there is a correlation between discounting of reward and control of movements. We consider saccadic eye movements and hypothesize that duration of a movement is equivalent to a delay of reward. The hyperbolic cost of this delay not only accounts for kinematics of saccades in adults, it also accounts for the faster saccades of children, who temporally discount reward more steeply. Our theory explains why saccade velocities increase when reward is elevated, and why disorders in the encoding of reward, for example in Parkinson's disease and schizophrenia, produce changes in saccade. We show that delay of reward elevates the cost of saccades, reducing velocities. Finally, we consider coordinated movements that include motion of eyes and head and find that their kinematics are also consistent with a hyperbolic, reward dependent cost of time. Therefore, each voluntary movement carries a cost because its duration delays acquisition of reward. The cost depends on the value that the brain assigns to stimuli, and the rate at which it discounts this value in time. The motor commands that move our eyes reflect this cost of time.

Aim The Discounting Inventory was developed to provide researchers and practitioners with a standardized tool to asses individual differences in delay, probabilistic, effort and social discounting, all related to behavioral impulsivity. Convergent and discriminant validity of the Discounting Inventory was evaluated by comparing its associations with external variables to those obtained using standardized discounting measures with the same external variables. Subjects and methods A sample of 347 volunteers was examined. The first questionnaire completed by all participants was the Discounting Inventory. Individuals also completed the traditional discounting measure using pairs of hypothetical choices. The external measures included the Sensation Seeking Scale, Barratt Impulsiveness Scale, Eysenck Impulsivity Venturesomeness Empathy Questionnaire, Eysenck Personality Questionnaire-Revised, and Temperament and Character Inventory. Results The results revealed that although almost all correlations were significant for both the Discounting Inventory and the traditional discounting measures, most of the correlations between external variables and the Discounting Inventory were significantly higher than those between external variables and traditional discounting measures. However, both discounting measures were most strongly correlated with external measures of impulsivity, which is not surprising given the fact that discounting is seen as a behavioral impulsivity. Finally, most relationships between the Discounting Inventory and external variables were incrementally valid over the traditional discounting measures. Conclusion The Discounting Inventory can help to diagnose problems with behavioral impulsivity.

Background: This study aimed at investigating the relationship between tasks that have been used in attention deficit hyperactivity disorder (ADHD) to measure choices between smaller immediate and larger delayed rewards: real and hypothetical temporal discounting tasks, and single-choice paradigms.Methods: Participants were 55 undergraduate psychology students. Tasks included a real and hypothetical version of a temporal discounting (TD) task with choices between a large reward (10 cents) after delays up to 60 seconds, and smaller immediate rewards (2–8 cents); two versions of a hypothetical temporal discounting task with choices between a large reward ($100) after delays up to 120 months, and smaller immediate rewards ($1–$95); a Choice Delay Task with choices between one point now and two points after 30 seconds (one point is worth five cents).Results: Correlation analyses showed that the real and the hypothetical TD tasks with 10 cents were very strongly associated. However, the hypothetical TD tasks with $100 did not correlate with either the real or the hypothetical TD task with 10 cents. Principal component analysis extracted two components: one for small amounts and short delays, and a second one for large rewards and long delays.Conclusions: Temporal reward discounting is not a uniform construct. Functional brain imaging research could shed more light on unique brain activation patterns associated with different forms of temporal reward discounting. Copyright © 2010 John Wiley & Sons, Ltd.

In temporal discounting, individuals often prefer smaller immediate rewards to larger delayed rewards, implying a trade off between the magnitude and delay of future rewards. While recent functional magnetic resonance imaging (fMRI) investigations of temporal discounting have generated conflicting findings, no studies have focused on whether distinct neural substrates respond to the magnitude and delay of future rewards. Combining a novel, temporally distributed discounting task with event-related fMRI, we found that while nucleus accumbens (NAcc), mesial prefrontal cortical (MPFC), and posterior cingulate cortical (PCC) activation positively correlated with future reward magnitude, dorsolateral prefrontal cortical (DLPFC) and posterior parietal cortical (PPC) activation negatively correlated with future reward delay. Further, more impulsive individuals showed diminished NAcc activation to the magnitude of future rewards and greater deactivations to delays of future rewards in the MPFC, DLPFC, and PPC. These findings suggest that while mesolimbic dopamine projection regions show greater sensitivity to the magnitude of future rewards, lateral cortical regions show greater (negative) sensitivity to the delay of future rewards, potentially reconciling different neural accounts of temporal discounting.

Some people find it more difficult to delay rewards than others. In three experiments, we tested a "future selfcontinuity" hypothesis that individual differences in the perception of one's present self as continuous with a future self would be associated with measures of saving in the laboratory and everyday life. Higher future self-continuity (assessed by a novel index) predicted reduced discounting of future rewards in a laboratory task, more matches in adjectival descriptions of present and future selves, and greater lifetime accumulation of financial assets (even after controlling for age and education). In addition to demonstrating the reliability and validity of the future self-continuity index, these findings are consistent with the notion that increased future self-continuity might promote saving for the future.

Delay discounting was examined in light smokers (10 or fewer cigarettes per day) and compared with previously published delay discounting data for heavy and never smokers. Participants evaluated several hypothetical outcomes: money gains and loses ($10, $100, and $1,000), health gains and losses (durations of improved and impoverished health subjectively equivalent to $1,000), cigarette gains and losses (amounts subjectively equivalent to $1,000), and potentially real rewards ($10 and $100). Light smokers discounted money significantly more than never smokers, but light smokers did not differ from heavy smokers. The 3 groups did not statistically differ in discounting of health consequences. Similarly, the 2 smoking groups were not found to differ in discounting of cigarettes. Like heavy smokers, light smokers discounted cigarettes significantly more than money and health. Several significant, positive correlations were found between smoking rate and various discounting measures in the heavy smokers but not in the light smokers. Several previous findings were replicated, helping to validate the present results: the sign effect (greater discounting of gains than losses), the magnitude effect (greater discounting of smaller rewards), reliability of discounting measures over time, and the consistency of hypothetical and potentially real rewards. These data suggest that even moderate levels of drug use may be associated with high delay discounting levels.

Critical to our many daily choices between larger delayed rewards, and smaller more immediate rewards, are the shape and the steepness of the function that discounts rewards with time. Although research in artificial intelligence favors exponential discounting in uncertain environments, studies with humans and animals have consistently shown hyperbolic discounting. We investigated how humans perform in a reward decision task with temporal constraints, in which each choice affects the time remaining for later trials, and in which the delays vary at each trial. We demonstrated that most of our subjects adopted exponential discounting in this experiment. Further, we confirmed analytically that exponential discounting, with a decay rate comparable to that used by our subjects, maximized the total reward gain in our task. Our results suggest that the particular shape and steepness of temporal discounting is determined by the task that the subject is facing, and question the notion of hyperbolic reward discounting as a universal principle.