Smokers discount their drug of abuse in the same way as other consumable rewards

Recent research shows that drug abusers discount delayed monetary rewards more than nonabusers do, and they discount delayed substances of abuse (e.g., drugs) more than delayed money. Furthermore, non-drug-abusers discount food and substances of abuse (e.g., alcohol), more than money. Here, we compare the delay and probability discounting of money with that of a directly consumable reward (chocolate) and with that of a substance of abuse (cigarettes), in a drug-using population (smokers). In line with previous research, we found in two experiments that delay discounting differentiated between smokers and nonsmokers, and between money and a nonabused directly consumable reward (chocolate). In addition, our results show that there appears to be no difference in the extent to which smokers discount their abused substance compared to another directly consumable reward. These findings support the contention that drugs and food are part of the same category of primary reinforcers, whereas money is discounted differently, as a conditioned reinforcer.     

Delay discounting as emotional processing: An electrophysiological study

Both theoretical models and functional imaging studies implicate the involvement of emotions within the delay discounting process. However, defining this role has been difficult to establish with neuroimaging techniques given the automaticity of emotional responses. To address this, the current study examined electrophysiological correlates involved in the detection and evaluation of immediate and delayed monetary outcomes. Our results showed that modulation of both early and later ERP components previously associated with affective stimuli processing are sensitive to the signalling of delayed rewards. Together with behavioural reaction times that favoured immediacy, we demonstrated, for the first time, that time delays modify the incentive value of monetary rewards via mechanisms of emotional bias and selective visual attention. Furthermore, our data are consistent with the hypothesis that delayed and thus intangible rewards are perceived less saliently, and rely on emotion as a common currency within decision making. This study provides a new approach to delay discounting and highlights a potential novel route through which delay discounting may be investigated.     

Math Weaknesses in Survivors of Acute Lymphoblastic Leukemia Compared to Healthy Children

Difficulties in math are the most frequently reported area of academic deficit in survivors of acute lymphoblastic leukemia (ALL) and the most frequent academic complaint among parents of ALL survivors. However, previous studies that included measures of math skills have been limited by the use of only a single measure of math skills, most often a measure of written calculations, without any assessment of math reasoning or math application skills. Further, the nature of these math difficulties has not been adequately investigated. The purpose of this study was to examine the performance of ALL survivors using multiple measures of math skills. Performance was compared to a group of healthy controls matched for age and sex as well as to normative levels. Other measures of neuropsychological function were also administered, and the relationships between these measures and the math measures were explored. Converging evidence for math difficulties in ALL survivors compared to healthy controls and normative levels was found. While ALL survivors generally performed within the average range on measures of math skills, math performance was mostly related to memory function and dominant-hand psychomotor speed. By contrast, math performance of healthy children was mostly related to basic reading skills and visual-motor integration. These findings shed light on the nature of math difficulties in ALL survivors and have implications for intervention.     

From data through discount rates to the area under the curve

The rate of discounting future goods is a crucial factor in intertemporal trade-offs, upon which depends not only individual well-being but also that of our planet: How much privation now for a temperate future for our grandchildren? What is the best way to measure how the value of future goods decreases with its delay? The most accurate discount functions involve several covarying parameters, making interpretation equivocal. A universal and robust measure is the area under the discount curve, the AuC. The AuC of a hyperbolic discount function is a logarithmic function of the discount rate, k. The same integral also approximates the area under a hyperboloid function. A simple technique converts each datum into estimates of the discount rate, eliminating rogue data points in the process. These trimmed estimates are converted into areas and tested against data, where they succeed at predicting the AuC and its relation to log(k).     

Accounting for Time Preference in Management Decisions: An Application to Invasive Species

Managers of invasive species seek to prevent and mitigate their impact, which vary in the time horizon over which they are realized. Likewise, stakeholders vary in the time horizons they consider relevant. Agricultural impacts might reasonably be considered over two or three decades, although ecologists typically consider environmental impacts over much longer time frames. Although time preference plays a critical role in decision making, it has largely been ignored in multicriteria analyses. In this study, we examine how time has been treated in previous decision analyses of invasive species management, focusing on the differences between multicriteria and economic cost–benefit analyses. We then outline a method for incorporating time preference information into multicriteria decision analyses to ensure that criteria weights remain a faithful representation of the decision maker's preferences. To illustrate how time preference can be elicited for invasive species problems involving both monetary and nonmonetary consequences, we describe a small empirical study we conducted with a small group of experts and managers. By outlining a way to consider time preference information in multicriteria analyses of invasive species management, we hope to facilitate better decision making that is reflective of the decision maker's true preferences. Copyright © 2013 John Wiley & Sons, Ltd.     

Gricean Expectations in Online Sentence Comprehension: An ERP Study on the Processing of Scalar Inferences

There is substantial support for the general idea that a formalization of comprehenders' expectations about the likely next word in a sentence helps explaining data related to online sentence processing. While much research has focused on syntactic, semantic, and discourse expectations, the present event‐related potentials (ERPs) study investigates neurolinguistic correlates of pragmatic expectations, which arise when comprehenders expect a sentence to conform to Gricean Maxims of Conversation. For predicting brain responses associated with pragmatic processing, we introduce a formal model of such Gricean pragmatic expectations, using an idealized incremental interpreter. We examine whether pragmatic expectancies derived from this model modulate the amplitude of the N400, a component that has been associated with predictive processing. As part of its parameterization, the model distinguishes genuine pragmatic interpreters, who expect maximally informative true utterances, from literal interpreters, who only expect truthfulness. We explore the model's non‐trivial predictions for an experimental setup which uses picture‐sentence verification with ERPs recorded at several critical positions in sentences containing the scalar implicature trigger some. We find that Gricean expectations indeed affect the N400, largely in line with the predictions of our model, but also discuss discrepancies between model predictions and observations critically.