Temporal discounting of rewards in patients with bipolar disorder and schizophrenia.

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. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Moderate drug use and delay discounting: A comparison of heavy, light, and never smokers.

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Affect regulation and temporal discounting: Interactions between primed, state, and trait affect.

Previous research has largely focused on the influence of experienced affect on decision making; however, other sources of affective information may also shape decisions. In two studies, we examine the interacting influences of affective information, state affect, and personality on temporal discounting rates (i.e., the tendency to choose small rewards today rather than larger rewards in the future). In Study 1, participants were primed with either positive or negative affect adjectives before making reward choices. In Study 2, participants underwent either a positive or negative affect induction before making reward choices. Results in both studies indicate that neuroticism interacts with state unpleasant affect and condition (i.e., positive or negative primes or induction) to predict discounting rates. Moreover, the nature of the interactions depends on the regulatory cues of the affective information available. These results suggest that irrelevant (i.e., primes) and stable (i.e., personality traits) sources of affective information also shape judgments and decision making. Thus, current affect levels are not the only source of affective information that guides individuals when making decisions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Alcohol demand, delayed reward discounting, and craving in relation to drinking and alcohol use disorders.

A behavioral economic approach to alcohol use disorders (AUDs) emphasizes both individual and environmental determinants of alcohol use. The current study examined individual differences in alcohol demand (i.e., motivation for alcohol under escalating conditions of price) and delayed reward discounting (i.e., preference for immediate small rewards compared to delayed larger rewards) in 61 heavy drinkers (62% with an AUD). In addition, based on theoretical accounts that emphasize the role of craving in reward valuation and preferences for immediate rewards, craving for alcohol was also examined in relation to these behavioral economic variables and the alcohol-related variables. Intensity of alcohol demand and delayed reward discounting were significantly associated with AUD symptoms, but not with quantitative measures of alcohol use, and were also moderately correlated with each other. Likewise, craving was significantly associated with AUD symptoms, but not with alcohol use, and was also significantly correlated with both intensity of demand and delayed reward discounting. These findings further emphasize the relevance of behavioral economic indices of motivation to AUDs and the potential importance of craving for alcohol in this relationship. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The short of it: Abbreviating the temporal discounting procedure.

A typical temporal discounting procedure determines the present, subjective value (indifference point) of a delayed outcome at 5 to 8 different delays to that outcome. These indifference points are used to determine a single index of discounting called a discounting rate. One concern that remains in the collection of this data is the high number of trials or choices, resulting in participant fatigue or other factors that may affect the validity of the data. In this report, we propose an abbreviated alternative to the more comprehensive and time-consuming discounting procedure. Specifically, we propose that fewer indifference points can be used to determine statistically equivalent discount rates with no loss in data sensitivity. We reanalyzed temporal discounting data obtained with 7 indifference points, and estimated discount rates from all combinations of 2, 3, and 4 of the 7 indifference points. Results indicate that valid and sensitive discounting indices can be obtained with fewer indifference points, and the most appropriate sets of indifference points are highlighted. The proposed abbreviated procedure is likely to be particularly useful when time constraints or participant fatigue is a concern as well as in repeated-measures contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discounting future green: Money versus the environment.

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Delay discounting in current and former marijuana-dependent individuals.

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 $1,000 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 differences in discounting were detected among the groups; however, currently dependent users showed a trend to discount money more than the other 2 groups. Within the dependent marijuana group, marijuana was discounted more than money, and discounting for money and marijuana was 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 3 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 toward increased delay discounting, but this effect size appears to be smaller for marijuana than for previously examined drugs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception of anticipatory time in temporal discounting.

The current article focuses on the role of anticipatory time perception in temporal discounting. We propose a perceived-time–based model and demonstrate that 2 aspects of time perception are relevant to hyperbolic discounting. Specifically, our model states that diminishing sensitivity to longer time horizons (i.e., how long individuals perceive short time horizons to be relative to long time horizons) and the level of time contraction overall (i.e., how long or short individuals perceive time horizons to be overall) contribute to the degree of hyperbolic discounting. We estimate individual differences in the degree of diminishing sensitivity to time and the degree of time contraction, and demonstrate that each significantly predicts the degree of hyperbolic discounting. These results empirically confirm two unique aspects of anticipatory time perception in determining individuals’ temporal discounting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal Discounting When the Choice Is Between Two Delayed Rewards.

The present experiments extend the temporal discounting paradigm from choice between an immediate and a delayed reward to choice between 2 delayed rewards: a smaller amount of money available sooner and a larger amount available later. Across different amounts and delays, the data were consistently well described by a hyperbola-like discounting function, and the degree of discounting decreased systematically as the delay to the sooner reward increased. Three theoretical models (the elimination-by-aspects, present-value comparison, and common-aspect attenuation hypotheses) were evaluated. The best account of the data was provided by the common-aspect attenuation hypothesis, according to which the common aspect of the choice alternatives (i.e., the time until the sooner reward is available) receives less weight in the decision-making process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Positive mood effects on delay discounting.

Delay discounting is the process by which the value of an expected reward decreases as the delay to obtaining that reward increases. Individuals with higher discounting rates tend to prefer smaller immediate rewards over larger delayed rewards. Previous research has indicated that personality can influence an individual's discounting rates, with higher levels of Extraversion predicting a preference for immediate gratification. The current study examined how this relationship would be influenced by situational mood inductions. While main effects were observed for both Extraversion and cognitive ability in the prediction of discounting rates, a significant interaction was also observed between Extraversion and positive affect. Extraverted individuals were more likely to prefer an immediate reward when first put in a positive mood. Extraverts thus appear particularly sensitive to impulsive, incentive-reward-driven behavior by temperament and by situational factors heightening positive affect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Imagining the future: Degraded representations of future rewards and events in schizophrenia.

Over the course of life, most people work toward temporally distant rewards such as university degrees or work-related promotions. In contrast, many people with schizophrenia show deficits in behavior oriented toward long-term rewards, although they function adequately when rewards are more immediately present. Moreover, when asked about possible future events, individuals with schizophrenia show foreshortened future time perspectives relative to healthy individuals. Here, we take the view that these deficits are related and can be explained by cognitive deficits. We compared the performance of participants with schizophrenia (n = 39) and healthy participants (n = 25) on tasks measuring reward discounting and future event representations. Consistent with previous research, we found that relative to healthy participants, those with schizophrenia discounted the value of future rewards more steeply. Furthermore, when asked about future events, their responses were biased toward events in the near future, relative to healthy participants' responses. Although discounting and future representations were unrelated in healthy participants, we found significant correlations across the tasks among participants with schizophrenia, as well as correlations with cognitive variables and symptoms. Further analysis showed that statistically controlling working memory eliminated group differences in task performance. Together these results suggest that the motivational deficits characteristic of schizophrenia relate to cognitive deficits affecting the ability to represent and/or evaluate distant outcomes, a finding with important implications for promoting recovery from schizophrenia. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Three-month stability of delay and probability discounting measures.

Psychopharmacologists are interested in delay and probability discounting because the tendency to discount the value of future and uncertain rewards has been linked with drug dependency. However, relatively little is known about the long-term stability of discounting measures typically studied in clinical psychopharmacology. To evaluate the stability of discounting over a 3-month period, the authors compared points of subjective equality (indifference points) with those collected from the same subjects 3 months earlier. Seven delay periods, ranging from 1 week to 25 years, and 7 probability values, ranging from .95 to .05, were assessed in an undergraduate sample (n=22, delay discounting; n=18, probability discounting). The authors examined both differential stability (stability of individual differences) and absolute stability (stability of the group mean) of delay and probability discounting measures as well as their respective indifference points. The results demonstrate that standard delay and probability discounting parameters (e.g., hyperbolic k and area under the curve) had both differential stability and absolute stability across 3 months. Moreover, most indifference points in the delay and probability discounting tasks demonstrated both differential and absolute stability. All together, these results suggest that delay and probability parameters are stable enough to predict future behavior, such as substance abuse. Additional findings indicated that a hyperbolic function fitted the data better than an exponential function and that delay and probability discounting parameters were not significantly correlated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Delay discounting in current and never-before cigarette smokers: Similarities and differences across commodity, sign, and magnitude.

Research has found that nicotine-dependent individuals delay discount monetary gains at a higher rate than matched controls. Delay discount rates, however, have also been found to vary across within-subject variables such as the magnitude of the outcome (e.g., $10 or $1,000), whether the outcome constitutes a gain or a loss, and the commodity being evaluated (e.g., money or health). The present study comprehensively investigated the differences in delay discounting between current and never-before cigarette smokers and across these within-subject variables. Both groups exhibited a magnitude, sign, and commodity effect. Current smokers' delay discount rates for monetary outcomes, however, were higher than never-before smokers across all magnitudes and both signs. This trend was also found for delayed health outcomes, but failed to reach significance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Disinhibitory psychopathology and delay discounting in alcohol dependence: Personality and cognitive correlates.

Increased discounting of delayed rewards may reflect a decision bias that contributes to excessive use of alcohol and more generally, to an impulsive, disinhibitory predisposition that is characterized by a preference for immediate over long-term rewards. The current study examined the association between delay discounting of rewards and the covariation among several types of disinhibitory problems that are often comorbid with alcohol dependence (AD). Lifetime problems with alcohol, marijuana, other drugs, childhood conduct disorder, and adult antisocial behavior were assessed in a sample of 426 young adults, 257 of whom had a lifetime diagnosis of AD. Higher delay discounting rates were associated with the covariation among all domains of disinhibitory problems and were not uniquely associated with any one domain. Higher delay discounting rates also were associated with lower intelligence, lower working memory capacity, and higher trait impulsivity. The results suggest that increased delay discounting of rewards may reflect aspects of a general vulnerability to externalizing, disinhibitory disorders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does working memory load lead to greater impulsivity? Commentary on Hinson, Jameson, and Whitney (2003).

Previous research by J. M. Hinson, T. L. Jameson, and P. Whitney (2003; see record 2003-02055-011) demonstrated that a secondary task in a delayed discounting paradigm increased subjects' preference for the immediate reward. J. M. Hinson et al. interpreted their findings as evidence that working memory load results in greater impulsivity. The present authors conducted a reanalysis of the data from J. M. Hinson et al.'s Experiment 1 at the individual-subject level. Difference scores were calculated by subtracting the digit memory load condition from the control condition for k (discounting parameter) and a measure of "erroneous" responses. The results indicated that the secondary task increased random responding, which in turn can account for the increased mean estimates of k. Thus, the data do not support the claim that cognitive load affects impulsivity per se. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pathological gamblers discount probabilistic rewards less steeply than matched controls.

Nineteen treatment-seeking men meeting Diagnostic and Statistical Manual for Mental Disorders (4th ed.) criteria for pathological gambling and 19 demographically matched controls participated. Participants provided demographic information, information about their recent drug use and gambling activities, and biological samples (to confirm drug abstinence). They also completed the Eysenck Personality Questionnaire, the South Oaks Gambling Screen (SOGS), and 2 questionnaires designed to separately quantify probability and delay discounting. Pathological gamblers discounted probabilistic rewards significantly less steeply than matched controls. A significant correlation revealed that more shallow probability discounting was associated with higher SOGS scores. Across groups, there was no significant difference in delay discounting, although this difference approached significance when education and ethnicity were included as covariates. These findings, collected for the 1st time with pathological gamblers, are consistent with previous reports that problem-gambling college students discount probabilistic rewards less steeply than controls. The nature of the relation between probability discounting and severity of problem gambling is deserving of further study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discounting of past outcomes.

Drug use, abuse, and addiction are common behavioral manifestations of impulsiveness. A useful and popular laboratory analogue of impulsiveness is temporal discounting. Temporal discounting refers to the reduction in the present, subjective value of outcomes that are temporally distant in the future. The extensive literature on temporal discounting indicates hyperbolic discounting, the magnitude effect, and the sign effect. It is possible that the same principles may apply to other dimensions of psychological distance, including past temporal distance. The purpose of the present study was to examine the possibility that outcomes in the past are discounted hyperbolically and at a similar rate to outcomes in the future. The magnitude and sign effects were also examined in past discounting. Indifference points of college students were determined from a paper-and-pencil questionnaire of future and past discounting. The results demonstrate that humans discount temporally distant past outcomes similarly to future outcomes. Discounting of the future and past are qualitatively and quantitatively similar; discounting of past outcomes is orderly, hyperbolic, and consistent with most empirical observations from studies of future discounting, including the magnitude and sign effects. The present study indicates that the discounting of past outcomes is a quantifiable phenomenon, and the results are similar to observations from the established future-discounting literature. Past discounting may be of use in the study of drug-dependent and other impulsive populations. Implications of a relationship between future and past discounting are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal discounting in choice between delayed rewards: The role of age and income.

This study examined the effects of age and income on temporal discounting (i.e., the decrease in the subjective value of a reward as the delay to its receipt increases). The value of delayed hypothetical monetary rewards was discounted at similar rates by adults of different ages but similar income levels, but at different rates by adults of similar age but different income levels. Specifically, lower income older adults showed a greater degree of temporal discounting than did either upper income older adults or upper income younger adults, but there were no age differences in discounting between the upper income groups. Comparison of these findings with those of a previous study (Green, Fry, & Myerson, 1994) suggests that impulsivity in decision making declines rapidly in young adulthood, reaching stable levels in the 30s. Further, age and income appear to interact in determining the impulsivity of decision making by adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Discounting Framework for Choice With Delayed and Probabilistic Rewards.

When choosing between delayed or uncertain outcomes, individuals discount the value of such outcomes on the basis of the expected time to or the likelihood of their occurrence. In an integrative review of the expanding experimental literature on discounting, the authors show that although the same form of hyperbola-like function describes discounting of both delayed and probabilistic outcomes, a variety of recent findings are inconsistent with a single-process account. The authors also review studies that compare discounting in different populations and discuss the theoretical and practical implications of the findings. The present effort illustrates the value of studying choice involving both delayed and probabilistic outcomes within a general discounting framework that uses similar experimental procedures and a common analytical approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)