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.     

Individual Differences in Delay Discounting: Differences are Quantitative with Gains,but Qualitative with Losses

Research on delay discounting and inter‐temporal choice has yielded significant insights into decision making. Although research has focused on delayed gains, the discounting of losses is potentially important in precisely those areas where the discounting of gains has proved informative (e.g., substance use and abuse). Participants in the current study completed both a questionnaire consisting of choices between immediate and delayed gains and an analogous questionnaire consisting of choices between immediate and delayed losses. For almost all participants, the likelihood of choosing the delayed gain decreased with increases in the wait until it would be received. In contrast, when losses (i.e., payments) were involved, different participants showed quite different patterns of choices. More specifically, although the majority of the participants became increasingly likely to choose to pay later as the delay was increased, some participants appeared to be debt averse, in that they were more likely to choose the immediate payment option when the delay was long than when it was brief. These debt‐averse participants also were more likely to choose to wait for a larger delayed gain than other participants and scored lower on Impulsiveness than those who showed the typical pattern of discounting delayed losses. Taken together, these results suggest that in the case of delayed gains, people differ only quantitatively (i.e., in how steeply they discount), whereas in the case of delayed losses, people differ qualitatively as well as quantitatively, contrary to the common assumption that a single impulsivity trait underlies choices between immediate and delayed outcomes. Copyright © 2016 John Wiley & Sons, Ltd.     

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。     

自尊水平、事件效价与时距对过去事件时距估计的影响

在西方文化背景下提出的时间自我评价理论认为,人们为了维护当前积极自尊,主观上会远离过去失败而亲近过去成功。本研究采用线段评估法,选取311名中国大学生被试,通过两个实验考察自尊水平、事件效价与时距对过去事件时距估计的影响,以检验该理论的文化普适性。结果表明:对过去事件的时距估计,自尊水平、事件效价及其交互作用在同一时距里均不存在显著差异;时距的主效应及其与事件效价的交互作用均显著,在负效价水平上存在显著时距差异,在正效价水平上无显著时距差异。研究结果不支持基于西方文化背景下的时间自我评价理论。     

Development of hot and cool executive function during the transition to adolescence

This study examined the development of executive function (EF) in a typically developing sample from middle childhood to adolescence using a range of tasks varying in affective significance. A total of 102 participants between 8 and 15 years of age completed the Iowa Gambling Task, the Color Word Stroop, a Delay Discounting task, and a Digit Span task. Age-related improvements were found on all tasks, but improvements on relatively cool tasks (Color Word Stroop and Backward Digit Span) occurred earlier in this age range, whereas improvements on relatively hot tasks (Iowa Gambling Task and Delay Discounting) were more gradual and occurred later. Exploratory factor analysis indicated that performance on all tasks could be accounted for by a single-factor model. Together, these findings indicate that although similar abilities may underlie both hot and cool EF, hot EF develops relatively slowly, which may have implications for the risky behavior often observed during adolescence. Future work should include additional measures to characterize more intensively the development of both hot and cool EF during the transition to adolescence.     

Neural correlates of metonymy resolution

Metonymies are exemplary models for complex semantic association processes at the sentence level. We investigated processing of metonymies using event-related functional magnetic resonance imaging (fMRI).During an 1.5 Tesla fMRI scan, 14 healthy subjects (12 female) read 124 short German sentences with either literal (like “Africa is arid”), metonymic (“Africa is hungry”), or nonsense (“Africa is woollen”) content. Sentences were constructed so that they obey certain grammatical, semantic, and plausibility conditions and were matched for word frequency, semantic association, length and syntactic structure. We concentrated on metonymies that were not yet fossilised; we also examined a wide variety of metonymic readings.Reading metonymies relative to literal sentences revealed signal changes in a predominantly left-lateralised fronto-temporal network with maxima in the left and right inferior frontal as well as left middle temporal gyri. Left inferior frontal activation may reflect both inference processes and access to world knowledge during metonymy resolution.     

Speed and Rhythm Affect Temporal Structure of Variability in Reaching Poststroke: A Pilot Study

Temporal structure reveals the potential adaptive strategies employed during upper extremity movements. The authors compared the temporal structure of upper extremity joints under 3 different reaching conditions: preferred speed, fast speed, and reaching with rhythmic auditory cues in 10 individuals poststroke. They also investigated the temporal structure of these 3 reaching conditions in 8 healthy controls to aid in the interpretation of the observed patterns in the poststroke cohort. Approximate entropy (ApEn) was used to measure the temporal structure of the upper extremity joints. ApEn was similar between conditions in controls. After stroke, ApEn was significantly higher for shoulder, elbow, and wrist both at fast speed and with rhythmic cues compared with preferred speed. ApEn at index finger was significantly higher only with rhythmic cues compared with preferred speed. The authors propose that practice reaching at faster speed and with rhythmic cues as a component of rehabilitation interventions may enhance adaptability after stroke.     

Grasp-Based Functional Coupling Between Reach- and Grasp-Related Components of Forelimb Muscle Activity

How are appropriate combinations of forelimb muscles selected during reach-to-grasp movements in the presence of neuromotor redundancy and important task-related constraints? The authors tested whether grasp type or target location preferentially influence the selection and synergistic coupling between forelimb muscles during reach-to-grasp movements. Factor analysis applied to 14–20 forelimb electromyograms recorded from monkeys performing reach-to-grasp tasks revealed 4–6 muscle components that showed transport/preshape- or grasp-related features. Weighting coefficients of transport/preshape-related components demonstrated strongest similarities for reaches that shared the same grasp type rather than the same target location. Scaling coefficients of transport/preshape- and grasp-related components showed invariant temporal coupling. Thus, grasp type influenced strongly both transport/preshape- and grasp-related muscle components, giving rise to grasp-based functional coupling between forelimb muscles.     

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.