Reinforcer pathology II: Reward magnitude,reward delay,and demand for alcohol collectively relate to college students' alcohol related problems

The reinforcer pathologies model of addiction posits that two characteristic patterns of operant behavior characterize addiction. Specifically, individuals suffering from addiction have elevated levels of behavioral economic demand for their substances of abuse and have an elevated tendency to devalue delayed rewards (reflected in high delay discounting rates). Prior research has demonstrated that these behavioral economic markers are significant predictors of many of college students' alcohol-related problems. Delay discounting, however, is a complex behavioral performance likely undergirded by multiple behavioral processes. Emerging analytical approaches have isolated the role of participants' sensitivity to changes in reinforcer magnitude and changes in reinforcer delay. The current study uses these analytic approaches to compare participants' discounting of money versus alcohol, and to build regression models that leverage these new insights to predict a wider range of college students' alcohol related problems. Using these techniques, we were able to 1) demonstrate that individuals differed in their sensitivity to magnitudes of alcohol versus money, but not sensitivity to delays to those commodities and 2) that we could use our behavioral economic measures to predict a range of students' alcohol related problems.     

Greater delay discounting among girls,but not boys,with ADHD correlates with cognitive control

Cognitive neuroscience models suggest both reward valuation and cognitive control contribute to reward-based decision-making. The current study examined the relationship between cognitive control and delay discounting (i.e., choosing smaller, immediate over larger, delayed rewards) in a large sample of boys and girls diagnosed with attention-deficit/hyperactivity disorder (ADHD; N = 95) and typically developing control children (TD; N = 59). Specifically, we examined performance on multiple measures of cognitive control (i.e., Go/No-Go task, Stop Signal task, and Spatial Span task) and delay discounting (i.e., Classic Delay Discounting and Real-Time Delay Discounting tasks), as well as the relationship between these measures. Results indicated that sex moderated the effects of group on task performance. Specifically, girls with ADHD, but not boys with the disorder, exhibited atypical delay discounting of real-time rewards. Results from correlational analyses indicated that delay discounting and cognitive control were not significantly correlated in the overall sample. Multiple regression analyses demonstrated that among girls with ADHD poorer spatial working memory and inhibitory control predicted greater real-time discounting. Collectively, findings provide support for distinct patterns of cognitive control and delay discounting among school-aged girls and boys with ADHD. Additionally, findings suggest that among girls with ADHD, those who exhibit relatively poor working memory and inhibitory control might be a particularly vulnerable subgroup with the greatest propensity to exhibit maladaptive decision-making.     

The Matching Law And Amount-dependent Exponential Discounting As Accounts Of Self-control Choice

Studies with humans have found evidence for amount-dependent temporal discounting, that is, that the sensitivity of choice to reinforcer delay varies inversely with reinforcer magnitude. To test whether similar results could be obtained with nonhumans, pigeons were trained on a two-component concurrent-chains procedure in which the durations of food reinforcement in the terminal links were equal within components but unequal between components. Terminal-link schedules were varied over four conditions to allow separate estimates of sensitivity to delay to be obtained for the large and small reinforcer-magnitude components. Although sensitivity to delay was greater in the small-magnitude component for all subjects, the effect was quite small. The difference in sensitivity was generally less than one standard error, and t tests on parameter differences failed to reach significance. Several models for temporal discounting, including an amount-dependent exponential function, were fitted to the data from the first four conditions. The resulting parameter estimates were used to make predictions for a self-control condition in which one terminal link arranged a smaller, less delayed reinforcer and the other arranged a larger, more delayed reinforcer. For all models, predictions were considerably more accurate when sensitivity to delay was the same regardless of reinforcer magnitude. The results support the independence of delay and magnitude as required by a version of the matching law, and provide strong evidence against amount-dependent exponential discounting as an account of self-control choice. A new two-parameter discounting function, consistent with the matching law, is proposed that has wide empirical generality for both human and nonhuman data.     

A Measure of Delay Discounting Within the Academic Domain

It is important to better understand the decision‐making processes involved in student procrastination, in order to develop interventions that reduce this common problem. Students may procrastinate because studying produces delayed reinforcers; however, no task measuring delay discounting of academic outcomes currently exists. In Experiment 1, we developed and piloted a measure of academic discounting modeled on titrating‐amount tasks successfully used in the discounting literature. Participants made hypothetical choices between working for money (the smaller, sooner reinforcer) and working on an assignment that was due at various times (the larger, later reinforcer). Participants showed systematic decreases in the subjective value of the assignment as a function of delay, and the hyperbolic and hyperboloid models described the shape of this decrease in value well. In general, larger delayed rewards are discounted less steeply than smaller delayed rewards (the magnitude effect). In Experiment 2, we observed the magnitude effect in academic discounting: Participants discounted a “not important” assignment more steeply than an “important” assignment. In the hyperboloid model, this change was captured by an increase in the s parameter. Results provide support for the validity of the academic discounting task. Copyright © 2018 John Wiley & Sons, Ltd.     

环境损益的社会折扣:利他人格的影响

他人与自我之间的社会距离越远,则他人的获益或损失带给自我的效用就越小,此现象被称为社会折扣。虽然有一些研究探讨了金钱结果的社会折扣现象,但作为公共品的环境结果的社会折扣规律及其影响因素并未得到应有的研究。本研究以优劣空气天数为例,采用选择滴定程序,在损益两种情境下探索环境结果的社会折扣现象,并考察利他人格对社会折扣的影响。结果发现:(1)相比双曲模型,指数模型在损益两种情境下皆能更佳地拟合环境结果的社会折扣函数;(2)损益情境与社会距离的交互作用影响环境结果的社会折扣程度,损失情境下的社会折扣程度随社会距离的增加而变大的幅度大于收益情境;(3)利他人格在社会距离对社会折扣的影响中起调节作用。相比高利他人格者,低利他人格者的社会折扣受社会距离的影响较大。本研究对理解环境结果社会折扣和环保决策行为具有重要意义。     

A second type of magnitude effect: Reinforcer magnitude differentiates delay discounting between substance users and controls

Basic research on delay discounting, examining preference for smaller–sooner or larger–later reinforcers, has demonstrated a variety of findings of considerable generality. One of these, the magnitude effect, is the observation that individuals tend to exhibit greater preference for the immediate with smaller magnitude reinforcers. Delay discounting has also proved to be a useful marker of addiction, as demonstrated by the highly replicated finding of greater discounting rates in substance users compared to controls. However, some research on delay discounting rates in substance users, particularly research examining discounting of small‐magnitude reinforcers, has not found significant differences compared to controls. Here, we hypothesize that the magnitude effect could produce ceiling effects at small magnitudes, thus obscuring differences in delay discounting between groups. We examined differences in discounting between high‐risk substance users and controls over a broad range of magnitudes of monetary amounts ($0.10, $1.00, $10.00, $100.00, and $1000.00) in 116 Amazon Mechanical Turk workers. We found no significant differences in discounting rates between users and controls at the smallest reinforcer magnitudes ($0.10 and $1.00) and further found that differences became more pronounced as magnitudes increased. These results provide an understanding of a second form of the magnitude effect: That is, differences in discounting between populations can become more evident as a function of reinforcer magnitude.     

降低决策冲动性的方法及其神经机制

大量实验研究显示, 成瘾患者、多动症患者和病态赌博者在决策中表现出冲动偏好。目前研究冲动性决策偏好的经典实验范式是延迟折扣任务。通过延迟折扣任务, 心理学家揭示了冲动性决策偏好的神经机制并构建了多种理论, 包括单一系统评价理论、双系统评价理论、自我控制理论和自我参照加工理论。基于这些理论, 已经发展出了多种降低决策冲动性的方法, 包括想象未来具体事件、工作记忆训练、预先承诺以及提高血液中葡萄糖水平, 其背后的神经机制是通过认知控制和价值表征理论来实现的。未来研究方向需集中于价值计算、价值系统和多体素模式分析(MVPA)在改善决策冲动性以及内在机制研究上的应用。     

Timing of retirement: Including a delay discounting perspective in retirement models

This research examined the influence of delay and anticipated health and enjoyment on the amount of retirement savings sacrificed for early retirement. In addition to testing and supporting predictions that willingness to sacrifice retirement savings would be less with shorter delays to retirement, greater anticipated health, and greater anticipated enjoyment, an individual difference delay discounting measure derived from experimental studies was used to extend the Beehr, Glazer, Nielson, and Farmer’s (2000) model of retirement age. We predicted and found that oldest preferred retirement age related to personal characteristics, current work factors, future retirement factors, and individual differences in delay discounting, with greater delay discounting being associated with a younger preferred retirement age. Findings suggest that delay discounting is an important consideration in retirement planning and also highlight the significance that retirement expectations and being tired of work have in affecting one’s preferred retirement age.     

自我损耗促进冲动决策：来自行为和ERPs的证据

该研究以自我控制资源模型为理论框架, 采用行为实验和ERPs技术考察自我损耗对冲动决策的影响。实验1采用Stroop任务操纵自我控制资源并采用延迟折扣任务考察被试的决策冲动性, 实验2采用同样的实验任务并同时采用ERPs技术记录高、低自我损耗者在随后决策任务中的脑电成分。行为结果发现, 在控制心境、特质自我控制水平以及风险偏好等无关变量后, 高损耗者比低损耗者在延迟折扣任务上的折扣程度更大。ERPs结果发现, 不论延迟金额大小, 高损耗者在左侧额区诱发的N1波幅显著小于低损耗者; 高损耗者在右半球诱发的P2波幅显著大于低损耗者。研究表明, 自我损耗抑制决策早期左侧额区的激活水平, 个体因而无法识别冲突以及抵制即时满足的诱惑, 这促使他们采用直觉启发式进行决策, 最终导致冲动决策的产生。     

Associations Between Delay Discounting and Risk‐Related Behaviors,Traits, Attitudes,and Outcomes

Delay discounting—preference for immediate, smaller rewards over distal, larger rewards—has been argued to be part of the “generality of deviance”, which describes the co‐occurrence of various forms of impulsive and risky behaviors among individuals. Some studies have linked laboratory‐measured delay discounting to behaviors, traits, attitudes, and outcomes associated with risk, but these associations have been inconsistent. Furthermore, many of these studies have been conducted with exclusively undergraduate samples, or in samples offering low statistical power. In a large community sample (n = 328) diverse in age and socioeconomic status, we examined associations between two measures of behavioral delay discounting (single‐shot and canonical k‐parameter estimation) and behavioral risk‐taking, personality traits associated with risk, domain‐specific risk attitudes, gambling and problem gambling, antisocial behavior, and criminal outcomes. In addition, we explored whether a novel response time latency measure of delay discounting explained variance in these risk‐related outcomes. Results indicated that behavioral delay discounting was consistently associated with all variables related to impulse control: high trait impulsivity, low trait self‐control, risk‐averse attitudes toward financial investment, risk‐prone attitudes toward gambling and health/safety risks, gambling and problem gambling, antisocial conduct, and criminal outcomes. Latency‐measured delay discounting was inconsistently associated with behavioral delay discounting and risk‐related measures. Together, results suggest that delay discounting is associated with poor impulse control consistent with a generality of deviance account. Copyright © 2016 John Wiley & Sons, Ltd.     

Bidding for delayed rewards: Accumulation as delay discounting,delay discounting as regulation,demand functions as corollary

In the accumulation paradigm animals press one manipulandum to accumulate pellets or seconds of access to food, and then press another manipulandum, or run some distance, to collect it. The accumulation may be interpreted as delay discounting, with the animals adjusting the distal amount to compensate for its distance or delay. The amount accumulated before being collected is a linear function of the distance or time that the experimental paradigm stipulates for collecting it. That linear function follows from the Unit‐Price/Unit‐Amount axiom. The inverse of the linear compensation functions gives a delay‐discount hyperbola. The advantages of the accumulation paradigm and analytic framework for delay discounting studies are noted. Compensation functions are then derived from a behavioral regulation model, which generalizes them to contexts where the individual's budget for response cost becomes over‐taxed. In turn, such compensation/regulation models lead directly to representative demand functions. In sum, regulation models provide a theoretical grounding for demand functions, compensation functions, and delay discounting hyperbolas. The parameter that links them is the unit amount k, the slope of the compensation function and of the discount function, the setpoint for consumption in a regulation model, and the ideal quantity consumed at minimal price in a demand analysis.     

The sign effect,systematic devaluations and zero discounting

The sign effect is the steeper discounting of gains compared to losses. However, we see a greater sign effect on an individual level compared to an aggregate level. In this experiment, we compare discounting of gains and losses on an individual and aggregate level, to explore further details about when and to what extent human adults discount. Thirty-one participants went through a computer-based choice-task procedure of hypothetical monetary gains and losses. The results show clear qualitative differences between discounting of gains and losses, adding empirical data to support the sign effect. The results also support previous findings that show that aggregate and individual results do not always correspond. Further, the within-subject details showing zero discounting or nonsystematic changes concerning losses, replicate earlier studies suggesting that discounting of gains and losses involve different reinforcing contingencies. The present study expands on this research area by including verbal reports, supplementing details about the unobserved reinforcing contingencies. Implications of research on discounting may indicate how to deal with decision-making challenges and might shed light on why predictions about complex decision making sometimes fail.     

Examining children's ability to delay reward: Is the delay discounting task a suitable measure?

Discounting the value of delayed rewards has primarily been measured in children with the delay of gratification task and in adolescents and adults with the delay discounting task. In the present study, we assessed the suitability of the delay discounting task as a measure of temporal discounting in children. A sample of 7- to 9-year-olds (N = 98) completed a delay discounting task, a delay of gratification task, a sensation seeking measure, and IQ measures. In addition, teacher-based assessments of attention-deficit/hyperactivity disorder traits were measured. The results indicated that the majority of children produced meaningful data on the discounting task and discounted rewards hyperbolically. Children with an elevated risk of attention-deficit/hyperactivity disorder showed a trend towards discounting future rewards on the delay discounting task more steeply than did those at low risk. However, delay discounting was unrelated to either delay of gratification or sensation seeking. We interpret these results as providing some support for the use of delay discounting as a measure of intertemporal choice in children, although the results also suggest that delay discounting and delay of gratification tasks may tap different processes in this population.     

Individual differences in impulsive choice and timing in rats

Individual differences in impulsive choice behavior have been linked to a variety of behavioral problems including substance abuse, smoking, gambling, and poor financial decision-making. Given the potential importance of individual differences in impulsive choice as a predictor of behavioral problems, the present study sought to measure the extent of individual differences in a normal sample of hooded Lister rats. Three experiments utilized variations of a delay discounting task to measure the degree of variation in impulsive choice behavior across individual rats. The individual differences accounted for 22-55% of the variance in choice behavior across the three experiments. In Experiments 2 and 3, the individual differences were still apparent when behavior was measured across multiple choice points. Large individual differences in the rate of responding, and modest individual differences in timing of responding were also observed during occasional peak trials. The individual differences in timing and rate, however, did not correlate consistently with individual differences in choice behavior. This suggests that a variety of factors may affect choice behavior, response rate, and response timing.     

Control your cravings: Self-controlled food choice varies by eating attitudes,sex, and food type among Division I collegiate athletes

Eating attitudes are predictive of disordered eating, which can be quite prevalent among collegiate athletes. The present study tested if disordered eating attitudes and the sex of collegiate athletes are related to “self-controlled food choice” for four food types: a dessert, fried food, fruit, and vegetable. In total, 102 athletes completed a disordered eating attitudes assessment and a delay discounting task. For the delay discounting task, athletes chose between one large delayed reward and one successively smaller immediate reward for four food types, and indifference points were computed with lower indifference points indicating greater self-controlled food choice. In this study female athletes showed greater self-controlled food choice for all three tempting food types (dessert, fried food, and fruit), but not the control food type (vegetable). For males, results were moderated by their level of disordered eating attitudes. Overall, these data show that “self-controlled food choice,” measured using a delay discounting task, is a key factor related to sex differences in disordered eating attitudes among college athletes.     

The roles of delay and probability discounting in texting while driving: Toward the development of a translational scientific program

A sample of 109 college students completed a survey to assess how frequently they send or read text messages while driving. In a novel discounting task with a hypothetical scenario in which participants receive a text message while driving, they rated the likelihood of replying to a text message immediately versus waiting to reply until arriving at a destination. The scenario presented several delays to a destination and probabilities of a motor vehicle crash. The likelihood of waiting to reply decreased as a function of both the delay until the destination and the probability of a motor vehicle crash. Self‐reported higher frequencies of texting while driving were associated with greater rates of both delay and probability discounting. The degree of delay discounting was altered as a function of the probability of a motor vehicle crash and vice versa. These results suggest that both delay and probability discounting are important underlying mechanisms of drivers' decision to text while driving.     

概率贴现和时间贴现在人脑中的分离

本研究运用ERP技术来检验概率贴现和时间贴现是否反映了相同的神经机制过程。在本研究中,我们在一个刺激中同时操纵概率贴现（风险vs.安全）和时间贴现（1个月后vs.今天）水平。通过对两个过程上的ERN以及全时间段的ERP分析来确定它们是否反映了相同的认知过程。结果发现,这两者在ERN上存在差异,同时这两个效应在ERP的时程和出现的电极点上都存在差异。这些差异表明这两者可能包含着不同的神经机制过程。     

Notes on discounting

In general, if a variable can be expressed as a function of its own maximum value, that function may be called a discount function. Delay discounting and probability discounting are commonly studied in psychology, but memory, matching, and economic utility also may be viewed as discounting processes. When they are so viewed, the discount function obtained is hyperbolic in form. In some cases the effective discounting variable is proportional to the physical variable on which it is based. For example, in delay discounting, the physical variable, delay (D), may enter into the hyperbolic equation as kD. In many cases, however, the discounting data are not well described with a single-parameter discount function. A much better fit is obtained when the effective variable is a power function of the physical variable (kDS in the case of delay discounting). This power-function form fits the data of delay, probability, and memory discounting as well as other two-parameter discount functions and is consistent with both the generalized matching law and maximization of a constant-elasticity-of-substitution utility     

跨期选择的认知机制与神经基础

跨期选择是指个体对发生在不同时间的成本与收益进行权衡的决策过程。跨期选择的计算模型从经济学的角度用数学模型来建构时间折扣函数,而认知成分模型则从心理学的角度来研究跨期选择中的心理效应与认知成分。跨期选择的神经基础有三种不同的研究取向：双机制加工取向、单机制加工取向、自我控制取向。未来研究应该在跨期选择的认知机制、神经通路及运行机制、跨期选择的应用,以及从进化的角度对人与动物的跨期选择行为进行更深入的研究。     

Asymmetry of the group context effect on delay discounting

Binary choice delay discounting tasks require participants to indicate preference between smaller, immediate, and larger, delayed rewards. Previous research indicates that when the delayed reward is shared with others, the delayed outcome is preferred compared with when the outcomes are for the self only, resulting in lower rates of delay discounting. The present series of studies sought to replicate and extend this finding. Study 1 compared delay discounting on a standard task in which both immediate and delayed outcomes are for the self and a group context task where the delayed outcome was shared with one other person. Replicating previous results, group context resulted in lower rates of delay discounting, and this effect was independent of how the shared outcome was presented. Study 2 compared delay discounting on a standard task and a group context task where the immediate outcome was shared. In contrast to Study 1, group context resulted in higher rates of delay discounting, suggesting that preference in intertemporal choice tracks the shared outcome. Moreover, this effect was not independent of how the shared outcome was presented. This is the first study to reveal that group context, when applied to the immediate outcome, can result in higher rates of delay discounting.