RESUMEN
BACKGROUND: Cigarette smoking continues to be a major health concern and remains the leading preventable cause of death in the US. Recent efforts have been made to determine the potential health and policy benefits of reducing nicotine in combustible cigarettes. The degree to which changes in blood nicotine relate to measures of the abuse liability of reduced-nicotine cigarettes is unknown. The current study examined the relation between blood nicotine and behavioral economic demand measures of cigarettes differing in nicotine content. METHODS: Using a within-subject design, participants smoked a single cigarette during each experimental session. Cigarettes included the participant's usual-brand cigarette and SPECTRUM investigational cigarette differing in nicotine level (mg of nicotine to g of tobacco; 15.8 mg/g, 5.2 mg/g, 2.4 mg/g, 1.3 mg/g, and 0.4 mg/g). During each session, blood was collected at multiple timepoints and behavioral economic demand was assessed. Nonlinear mixed-effects models were used to estimate differences in derived intensity (Q0) and change in elasticity (α). RESULTS: Measures of blood nicotine decreased in an orderly fashion related to nicotine level and significantly predicted change in elasticity (α), but not derived intensity. No differences in demand parameters between the usual brand and 15.8mg/g cigarettes were observed. However, α was significantly higher (lower valuation) for 0.4mg/g than 15.8mg/g cigarettes. CONCLUSIONS: The lowest nicotine level (0.4mg/g) corresponded with the lowest abuse liability (α) compared to the full-strength control (15.8mg/g), with the 1.3mg/g level also resulting in low abuse liability. IMPLICATIONS: This is the first study examining the relative contributions of nicotine content in cigarettes and blood nicotine levels on the behavioral economic demand abuse liability of cigarettes ranging in nicotine content. Our results suggest blood nicotine and nicotine content both predict behavioral economic demand abuse liability. In addition, our results suggest a nicotine content of 1.3mg/g or lower may be effective at reducing cigarette uptake among first-time (naïve) smokers. Our results largely conform to previous findings suggesting a very low nicotine content cigarette maintains lower abuse liability than full-strength cigarettes.
Asunto(s)
Fumar Cigarrillos , Sistemas Electrónicos de Liberación de Nicotina , Productos de Tabaco , Economía del Comportamiento , Humanos , Nicotina/efectos adversos , Nicotiana , Productos de Tabaco/efectos adversosRESUMEN
INTRODUCTION: Cigarette smoking remains the leading preventable cause of death in the United States. Recent efforts have explored the potential health and policy benefits of reducing nicotine, an addictive component, in combustible cigarettes. To date, an experimental, prospective analysis directly comparing the effects of varying regulatory environments on purchases of multiple products has yet to be conducted. The present study compared real purchasing of conventional cigarettes, reduced-nicotine cigarettes, and a variety of other nicotine and tobacco products across a range of regulatory environments. METHODS: Participants were assigned to one of five groups, each associated with a different nicotine level (mg of nicotine to g of tobacco) in SPECTRUM investigational cigarettes (15.8, 5.2, 2.4, 1.3, and 0.4 mg/g). Across sessions, participants made real purchases for nicotine/tobacco products in an Experimental Tobacco Marketplace. Each session corresponded with a distinct regulatory environment wherein different nicotine/tobacco products were available for purchase. RESULTS: Our results suggest that the primary drivers of cigarette and nicotine purchasing are regulatory environment and the presence/absence of alternative nicotine and tobacco products. Perhaps surprisingly, nicotine level does not appear to be such a driver of purchasing behavior under these experimental conditions. Investigational cigarette purchasing is lowest when other preferred combustible products are available and highest when investigational cigarettes are the only combustible product available for purchase. CONCLUSIONS: If a reduced-nicotine policy is implemented, great care should be taken in determining and making available less-harmful nicotine/tobacco products as the availability of preferred combustible products may result in undesirable levels of purchasing. IMPLICATIONS: This is the first experimental study investigating different potential regulatory effects related to a reduced-nicotine policy by examining purchasing across a range of nicotine/tobacco products. Our results suggest the presence of affordable, highly preferred combustible products is likely to maintain tobacco purchasing at undesirable levels. To promote switching to less-harmful products, affordable alternate nicotine and tobacco products should be readily available. Finally, our results suggest that the availability of noncigarette products, not cigarette nicotine level, will most likely affect purchasing of reduced-nicotine cigarettes.
Asunto(s)
Sistemas Electrónicos de Liberación de Nicotina , Productos de Tabaco , Humanos , Masculino , Nicotina , Nicotiana , Uso de Tabaco , Estados UnidosRESUMEN
Reinforcer pathology theory stipulates that individuals with both (a) high preference for smaller, immediate over larger, delayed rewards; and (b) high demand for unhealthy commodities are uniquely susceptible to poor health outcomes. Specifically, two behavioral economic tasks (delay discounting, assessing preference for smaller, immediate or larger, delayed rewards; and purchasing, assessing purchases of commodities over changes in price) have been independently associated with conditions such as overweight/obesity and problem substance use. In the present study, we examined possible shared neural regions involved in the processes of delay discounting and demand for snack foods in a prediabetic sample. Fifty-four participants completed both of these tasks. Conjunction between delay discounting and purchasing task results indicates substantial common neural substrates recruited during these two tasks, consistent with interpretations of executive control, interoception, and attention, in the prefrontal cortex, insula, and frontoparietal cortex (superior/middle frontal cortex and superior/inferior parietal lobules), respectively. Collectively, these results suggest possible neural substrates in which the two behavioral risk factors of reinforcer pathology may interact during real-world decision-making in prediabetes.
Asunto(s)
Encéfalo/diagnóstico por imagen , Toma de Decisiones , Descuento por Demora , Función Ejecutiva , Estado Prediabético/psicología , Adulto , Atención , Encéfalo/fisiología , Femenino , Neuroimagen Funcional , Humanos , Conducta Impulsiva , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Lóbulo Parietal/diagnóstico por imagen , Lóbulo Parietal/fisiología , Corteza Prefrontal/diagnóstico por imagen , Corteza Prefrontal/fisiología , Recompensa , BocadillosRESUMEN
AIMS: Alcohol consumption is a modifiable and plausible risk factor for age-related cognitive decline but more longitudinal studies investigating the association are needed. Our aims were to estimate associations of adult-life alcohol consumption and consumption patterns with age-related cognitive decline. METHODS: We investigated the associations of self-reported adult-life weekly alcohol consumption and weekly extreme binge drinking (≥10 units on the same occasion) with changes in test scores on an identical validated test of intelligence completed in early adulthood and late midlife in 2498 Danish men from the Lifestyle and Cognition Follow-up study 2015. Analyses were adjusted for year of birth, retest interval, baseline IQ, education and smoking. RESULTS: Men with adult-life alcohol consumption of more than 28 units/week had a larger decline in IQ scores from early adulthood to late midlife than men consuming 1-14 units/week (B29-35units/week = -3.6; P < 0.001). Likewise, a 1-year increase in weekly extreme binge drinking was associated with a 0.12-point decline in IQ scores (P < 0.001). Weekly extreme binge drinking explained more variance in IQ changes than average weekly consumption. In analyses including mutual adjustment of weekly extreme binge drinking and average weekly alcohol consumption, the estimated IQ decline associated with extreme binge drinking was largely unaffected, whereas the association with weekly alcohol consumption became non-significant. CONCLUSIONS: Adult-life heavy alcohol consumption and extreme binge drinking appear to be associated with larger cognitive decline in men. Moreover, extreme binge drinking may be more important than weekly alcohol consumption in relation to cognitive decline.
Asunto(s)
Consumo de Bebidas Alcohólicas/psicología , Consumo de Bebidas Alcohólicas/terapia , Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Autoinforme , Pruebas Respiratorias , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de TiempoRESUMEN
BACKGROUND: The delivery of monetary incentives contingent on verified abstinence is an effective treatment for alcohol use disorder. However, technological barriers to accurate, frequent biochemical verification of alcohol abstinence have limited the dissemination of this technique. METHODS: In the present randomized parallel trial, we employed a breathalyzer that allows remote, user-verified collection of a breath alcohol sample, text messaging, and reloadable debit cards for remote delivery of incentives to evaluate a contingency management treatment for alcohol use disorder that can be delivered with no in-person contact. Treatment-seeking participants with alcohol use disorder (n = 40) were recruited from the community and randomized to either a contingent or a noncontingent group (n = 20 each). The contingent group received nearly immediate monetary incentives each day they remotely provided negative breathalyzer samples. The noncontingent group received matched monetary payments each day they successfully provided samples independent of alcohol content. Groups were not masked as awareness of group contingencies was an essential intervention component. RESULTS: The primary outcome of the intent-to-treat analyses (analyzed n = 40) was percent days abstinent as measured by the remote breathalyzer samples. Abstinence rates in the contingent group were 85%, which was significantly higher than the 38% recorded in the noncontingent group, corresponding to an odds ratio of 9.4 (95% CI = 4.0 to 22.2). Breathalyzer collection adherence rates were over 95%, and participant ratings of acceptability were also high. CONCLUSIONS: These results support the efficacy, acceptability, and feasibility of this remotely deliverable abstinence reinforcement incentive intervention for the initiation and near-term maintenance of abstinence from alcohol in adults with alcohol use disorder. Due to low provider and participant burden, this procedure has the potential for broad dissemination.
Asunto(s)
Alcoholismo/terapia , Monitoreo Fisiológico/métodos , Adulto , Abstinencia de Alcohol , Pruebas Respiratorias , Estudios de Factibilidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Motivación , Aceptación de la Atención de Salud , Resultado del TratamientoRESUMEN
The evolution of science derives, in part, from the development and use of new methods and techniques. Here, we discuss one development that may have impact on the understanding of tobacco regulatory science: namely, the application of behavioral economics to the complex tobacco marketplace. The purpose of this paper is to review studies that examine conditions impacting the degree to which electronic nicotine delivery system (ENDS) products substitute for conventional cigarettes in the Experimental Tobacco Marketplace (ETM). Collectively, the following factors constitute the current experimental understanding of conditions that will affect ENDS use and substitution for conventional cigarettes: increasing the base price of conventional cigarettes, increasing taxation of conventional cigarettes, subsidizing the price of ENDS products, increasing ENDS nicotine strength, and providing narratives that illustrate the potential health benefits of ENDS consumption in lieu of conventional cigarettes. Each of these factors are likely moderated by consumer characteristics, which include prior ENDS use, ENDS use risk perception, and gender. Overall, the ETM provides a unique method to explore and identify the conditions by which various nicotine products may interact with one another that mimics the real world. In addition, the ETM permits the efficacy of a broad range of potential nicotine policies and regulations to be measured prior to governmental implementation.
Asunto(s)
Comercio/economía , Economía del Comportamiento , Sistemas Electrónicos de Liberación de Nicotina/economía , Productos de Tabaco/economía , Comportamiento del Consumidor , Humanos , Nicotina/administración & dosificación , Fumar/economía , Cese del Hábito de Fumar/economía , ImpuestosRESUMEN
Introduction: The majority of cigarettes sold in the United States and abroad feature filter ventilation holes designed to dilute mainstream smoke. Although initially intended to produce a safer cigarette, data instead suggest that filter ventilation increases total harm from smoking. In the present study, we examined the effects of blocking ventilation holes on behavioral economic demand for cigarettes (i.e., consumption as a function of price). Methods: In a within-subjects design, regular smokers (N = 15) of ventilated cigarettes sampled vent-blocked cigarettes for 3 days. Subsequently, they completed three sessions in which they used an experimental income to purchase vent-blocked and/or control cigarettes across a range of prices. Participants also completed the Drug Effects/Liking Scale. Results: In sessions in which only one cigarette type was available, demand measures were undifferentiated between cigarette types. However, in sessions in which both cigarettes were available at equivalent prices, significantly greater preference for ventilated control cigarettes emerged in demand measures. Regardless of session type, participants also rated vent-blocked cigarettes more poorly in the Drug Effects/Liking Scale (more bad effects, fewer good effects, and less liking, desire, and less likely to use again). Conclusions: Removing filter ventilation reduced cigarette abuse liability, as measured by behavioral economic demand and the Drug Effects/Liking Scale. However, reduced demand was only apparent when both cigarette types were concurrently available. This selective effect suggests that regulatory action banning filter ventilation would only reduce cigarette consumption when effective substitutes for vent-blocked cigarettes are available. Implications: This preliminary study indicates that regulatory action designed to ban or restrict cigarette filter ventilation may decrease cigarette abuse liability as measured by both behavioral economic demand and self-report measures. However, effects of removing filter ventilation on demand measures appear to depend on concurrent availability of alternative, preferred cigarette types.
Asunto(s)
Fumar Cigarrillos/economía , Fumar Cigarrillos/tendencias , Comportamiento del Consumidor/economía , Economía del Comportamiento/tendencias , Productos de Tabaco/economía , Adulto , Fumar Cigarrillos/psicología , Comercio/economía , Ansia , Femenino , Humanos , Renta/tendencias , Masculino , Persona de Mediana Edad , Autoinforme , Fumadores/psicología , Tabaquismo/economía , Tabaquismo/psicología , Estados UnidosRESUMEN
Research on the rate at which people discount the value of future rewards has become increasingly prevalent as discount rate has been shown to be associated with many unhealthy patterns of behavior such as drug abuse, gambling, and overeating. fMRI research points to a fronto-parietal-limbic pathway that is active during decisions between smaller amounts of money now and larger amounts available after a delay. Researchers in this area have used different variants of delay discounting tasks and reported various contrasts between choice trials of different types from these tasks. For instance, researchers have compared 1) choices of delayed monetary amounts to choices of the immediate monetary amounts, 2) 'hard' choices made near one's point of indifference to 'easy' choices that require little thought, and 3) trials where an immediate choice is available versus trials where one is unavailable, regardless of actual eventual choice. These differences in procedure and analysis make comparison of results across studies difficult. In the present experiment, we designed a delay discounting task with the intended capability of being able to construct contrasts of all three comparisons listed above while optimizing scanning time to reduce costs and avoid participant fatigue. This was accomplished with an algorithm that customized the choice trials presented to each participant with the goal of equalizing choice trials of each type. We compared this task, which we refer to here as the individualized discounting task (IDT), to two other delay discounting tasks previously reported in the literature (McClure et al., 2004; Amlung et al., 2014) in 18 participants. Results show that the IDT can examine each of the three contrasts mentioned above, while yielding a similar degree of activation as the reference tasks. This suggests that this new task could be used in delay discounting fMRI studies to allow researchers to more easily compare their results to a majority of previous research while minimizing scanning duration.
Asunto(s)
Mapeo Encefálico/métodos , Descuento por Demora/fisiología , Conducta Impulsiva/fisiología , Imagen por Resonancia Magnética/métodos , Pruebas Neuropsicológicas , Adulto , Mapeo Encefálico/normas , Femenino , Humanos , Imagen por Resonancia Magnética/normas , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
Accumulating laboratory-based evidence indicates that reducing delay discounting (devaluation of delayed outcomes) with the use of episodic future thinking (EFT; mental simulation of future events) improves dietary decision-making and other maladaptive behaviors. Recent work has adapted EFT for use in the natural environment to aid in dietary and weight control by engaging participants in EFT repeatedly throughout the day. These efforts may benefit from minimizing the amount of time required for measurement and implementation of EFT. Using Amazon Mechanical Turk in the present study, we show that EFT effectively reduces delay discounting in overweight/obese participants (N = 131) using the recently developed 5-trial, adjusting-delay discounting task, which can be completed rapidly (25 s) and is therefore ideally suited for ecological momentary assessment. Moreover, measures of delay discounting from this task were strongly correlated with those from the commonly used adjusting-amount task (r = .859). Significant effects of EFT on discounting, however, depended on the number of future events participants generated and imagined. Use of a range of events and future time frames (as is typical in the literature) significantly reduced delay discounting, whereas use of only a single event did not.
Asunto(s)
Descuento por Demora , Predicción , Obesidad/psicología , Sobrepeso/psicología , Pensamiento , Adulto , Femenino , Humanos , Masculino , Adulto JovenRESUMEN
INTRODUCTION: Hypothetical rewards are commonly used in studies of laboratory-based tobacco demand. However, behavioral economic demand procedures require confirmation that the behavior elicited from real and hypothetical reward types are equivalent, and that results attained from these procedures are comparable to other accepted tasks, such as the hypothetical purchase task. METHODS: Nineteen smokers were asked to purchase 1 week's worth of cigarettes that they would consume over the following week either at one price that incrementally increased across four weekly sessions ("real" sessions) or four prices in a single session ("potentially real" session), one of which was randomly chosen to be actualized. At each session, participants also completed a hypothetical cigarette purchase task. After each week, participants reported the number of cigarettes they actually smoked. RESULTS: Demand was found to be equivalent under both the real and potentially real reward conditions but statistically different from the demand captured in the hypothetical purchase task. However, the amounts purchased at specific prices in the hypothetical purchase task were significantly correlated with the amount purchased at comparable prices in the other two tasks (except for the highest price examined in both tasks of $1.00 per cigarette). Number of cigarettes consumed that were obtained outside of the study was correlated with study cigarette price. CONCLUSIONS: Combined, these results suggest that purchasing behavior during potentially real sessions (1) was not functionally different from real sessions, (2) imposes fewer costs to the experimenter, and (3) has high levels of both internal and external validity.
Asunto(s)
Economía del Comportamiento , Modelos Teóricos , Fumar , Productos de Tabaco/economía , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Distribución Aleatoria , Fumar/economía , Fumar/psicologíaRESUMEN
INTRODUCTION: Behavioral economic studies of nicotine product consumption have traditionally examined substitution between two products and rarely examined substitution with more products. Increasing numbers of tobacco products available for commercial sale leads to more possible cross-product interactions, indicating a need to examine substitution in more complex arrangements that closely mirror the tobacco marketplace. METHODS: The experimental tobacco marketplace (ETM) is an experimental online store that displays pictures, information, and prices for several tobacco products. Smokers were endowed with an account balance based on their weekly tobacco purchases. Participants then made potentially real purchases for seven (Experiment 1) or six (Experiment 2) tobacco/nicotine products under four price conditions for conventional cigarettes while prices for other products remained constant. Smokers returned 1 week later to report tobacco/nicotine use and return unused products for a refund. RESULTS: In Experiment 1 (n = 22), cigarette purchasing decreased as a function of price. Substitution was greatest for electronic cigarettes and cigarillos and significant for electronic cigarettes. Experiment 2 (n = 34) was a replication of Experiment 1, but with cigarillos unavailable in the ETM. In Experiment 2, cigarette purchases decreased as a function of price. Substitution was robust and significant for electronic cigarettes and Camel Snus. CONCLUSIONS: The ETM is a novel, practical assay that mimics the real-world marketplace, and functions as a simple research tool for both researchers and participants. Across the two experiments the product mix in the ETM altered which products functioned as substitutes suggesting complex interactions between purchasing and product availability. IMPLICATIONS: This article adds a novel method of collecting purchasing data that mimics real world purchasing to the existing literature. The ETM is a practical avenue by which to study both hypothetical and potentially real purchasing.
Asunto(s)
Comportamiento del Consumidor , Internet , Mercadotecnía , Fumar/economía , Productos de Tabaco/economía , Adulto , Femenino , Humanos , Masculino , Cese del Hábito de Fumar/economía , Prevención del Hábito de Fumar , Estados Unidos , VirginiaRESUMEN
INTRODUCTION: Cigarette demand, or the change in cigarette consumption as a function of price, is a measure of reinforcement that is associated with level of tobacco dependence and other clinically relevant measures, but the effects of experimentally controlled income on real-world cigarette consumption have not been examined. METHODS: In this study, income available for cigarette purchases was manipulated to assess the effect on cigarette demand. Tobacco-dependent cigarette smokers (n = 15) who smoked 10-40 cigarettes per day completed a series of cigarette purchasing tasks under a variety of income conditions meant to mimic different weekly cigarette budgets: $280, approximately $127, $70, or approximately $32 per week. Prices of $0.12, $0.25, $0.50, and $1.00 per cigarette were assessed in each income condition. Participants were instructed to purchase as many cigarettes as they would like for the next week and to only consume cigarettes purchased in the context of the study. One price in 1 income condition was randomly chosen to be "real," and the cigarettes and the excess money in the budget for that condition were given to the participant. RESULTS: Results indicate that demand elasticity was negatively correlated with income. Demand intensity (consumption at low prices) was unrelated to income condition and remained high across incomes. CONCLUSIONS: These results indicate that the amount of income that is available for cigarette purchases has a large effect on cigarette consumption, but only at high prices.
Asunto(s)
Renta , Refuerzo en Psicología , Fumar/economía , Productos de Tabaco/economía , Tabaquismo/economía , Adulto , Comercio/economía , Femenino , Humanos , Masculino , Fumar/psicología , Tabaquismo/psicología , Adulto JovenRESUMEN
OBJECTIVE: Determine if employment-based reinforcement can increase methadone treatment engagement and drug abstinence in out-of-treatment injection drug users. METHOD: This study was conducted from 2008 to 2012 in a therapeutic workplace in Baltimore, MD. After a 4-week induction, participants (N=98) could work and earn pay for 26 weeks and were randomly assigned to Work Reinforcement, Methadone & Work Reinforcement, and Abstinence, Methadone & Work Reinforcement conditions. Work Reinforcement participants had to work to earn pay. Methadone & Work Reinforcement and Abstinence, Methadone, & Work Reinforcement participants had to enroll in methadone treatment to work and maximize pay. Abstinence, Methadone, & Work Reinforcement participants had to provide opiate- and cocaine-negative urine samples to maximize pay. RESULTS: Most participants (92%) enrolled in methadone treatment during induction. Drug abstinence increased as a graded function of the addition of the methadone and abstinence contingencies. Abstinence, Methadone & Work Reinforcement participants provided significantly more urine samples negative for opiates (75% versus 54%) and cocaine (57% versus 32%) than Work Reinforcement participants. Methadone & Work Reinforcement participants provided significantly more cocaine-negative samples than Work Reinforcement participants (55% versus 32%). CONCLUSION: The therapeutic workplace can promote drug abstinence in out-of-treatment injection drug users. Clinical trial registration number: NCT01416584.
Asunto(s)
Analgésicos Opioides/uso terapéutico , Trastornos Relacionados con Cocaína/tratamiento farmacológico , Trastornos Relacionados con Cocaína/psicología , Metadona/uso terapéutico , Trastornos Relacionados con Opioides/tratamiento farmacológico , Trastornos Relacionados con Opioides/psicología , Lugar de Trabajo/psicología , Baltimore , Trastornos Relacionados con Cocaína/orina , Empleo/psicología , Conductas Relacionadas con la Salud , Hospitales de Enseñanza , Humanos , Entrevistas como Asunto , Motivación , Trastornos Relacionados con Opioides/orina , Refuerzo en Psicología , Detección de Abuso de Sustancias , Abuso de Sustancias por Vía Intravenosa , Resultado del TratamientoRESUMEN
The field of behavioral economics has made important inroads into the understanding of substance use disorders through the concept of reinforcer pathology. Reinforcer pathology refers to the joint effects of (a) the persistently high valuation of a reinforcer, broadly defined to include tangible commodities and experiences, and/or (b) the excessive preference for the immediate acquisition or consumption of a commodity despite long-term negative outcomes. From this perspective, reinforcer pathology results from the recursive interactions of endogenous person-level variables and exogenous environment-level factors. The current review describes the basic principles of behavioral economics that are central to reinforcer pathology, the processes that engender reinforcer pathology, and the approaches and procedures that can repair reinforcement pathologies. The overall goal of this review is to present a new understanding of substance use disorders as viewed by recent advances in behavioral economics.
Asunto(s)
Conducta de Elección , Motivación , Refuerzo en Psicología , Trastornos Relacionados con Sustancias/psicología , Economía del Comportamiento , HumanosRESUMEN
Previous research comparing obese and non-obese samples on the delayed discounting procedure has produced mixed results. The aim of the current study was to clarify these discrepant findings by comparing a variety of temporal discounting measures in a large sample of internet users (n=1163) obtained from a crowdsourcing service, Amazon Mechanical Turk (AMT). Measures of temporal, social-temporal (a combination of standard and social temporal), and probability discounting were obtained. Significant differences were obtained on all discounting measures except probability discounting, but the obtained effect sizes were small. These data suggest that larger-N studies will be more likely to detect differences between obese and non-obese samples, and may afford the opportunity, in future studies, to decompose a large obese sample into different subgroups to examine the effect of other relevant measures, such as the reinforcing value of food, on discounting.
Asunto(s)
Conducta de Elección , Colaboración de las Masas/métodos , Obesidad/metabolismo , Conducta Social , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Índice de Masa Corporal , Toma de Decisiones , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Probabilidad , Encuestas y Cuestionarios , Adulto JovenRESUMEN
Standard nonlinear regression is commonly used when modeling indifference points due to its ability to closely follow observed data, resulting in a good model fit. However, standard nonlinear regression currently lacks a reasonable distribution-based framework for indifference points, which limits its ability to adequately describe the inherent variability in the data. Software commonly assumes data follow a normal distribution with constant variance. However, typical indifference points do not follow a normal distribution or exhibit constant variance. To address these limitations, this paper introduces a class of nonlinear beta regression models that offers excellent fit to discounting data and enhances simulation-based approaches. This beta regression model can accommodate popular discounting functions. This work proposes three specific advances. First, our model automatically captures non-constant variance as a function of delay. Second, our model improves simulation-based approaches since it obeys the natural boundaries of observable data, unlike the ordinary assumption of normal residuals and constant variance. Finally, we introduce a scale-location-truncation trick that allows beta regression to accommodate observed values of 0 and 1. A comparison between beta regression and standard nonlinear regression reveals close agreement in the estimated discounting rate k obtained from both methods.
RESUMEN
Substance abusers, including cocaine abusers, discount delayed rewards to a greater extent than do matched controls. In the current experiment, individual differences in discounting of delayed rewards in rats (choice of one immediate over three delayed sucrose pellets) were assessed for associations with demand for either sucrose pellets or an intravenous dose of 0.1 mg/kg/infusion cocaine. Twenty-four male Sprague Dawley rats were split into three groups based on sensitivity to delay to reinforcement. Then, demand for sucrose pellets and cocaine was determined across a range of fixed-ratio values. Delay discounting was then reassessed to determine the stability of this measure over the course of the experiment. Individual differences in impulsive choice were positively associated with elasticity of demand for cocaine, a measure of reinforcer value, indicating that rats having higher discount rates also valued cocaine more. Impulsive choice was not associated with the level of cocaine consumption as price approached 0 or with any parameter associated with demand for sucrose. Individual sensitivity to delay was correlated with the initial assessment when reassessed at the end of the experiment, although impulsive choice increased for this cohort of rats as a whole. These findings suggest that impulsive choice in rats is positively associated with valuation of cocaine, but not sucrose.
Asunto(s)
Cocaína/administración & dosificación , Inhibidores de Captación de Dopamina/administración & dosificación , Comportamiento de Búsqueda de Drogas , Conducta Impulsiva/psicología , Individualidad , Sacarosa/administración & dosificación , Animales , Trastornos Relacionados con Cocaína/psicología , Condicionamiento Operante , Economía del Comportamiento , Masculino , Ratas , Ratas Sprague-Dawley , Refuerzo en Psicología , Estadística como Asunto , Factores de TiempoRESUMEN
Delay discounting reflects the rate at which a reward loses its subjective value as a function of delay to that reward. Many models have been proposed to measure delay discounting, and many comparisons have been made among these models. We highlight the two-parameter delay discounting model popularized by Howard Rachlin by demonstrating two key practical features of the Rachlin model. The first feature is flexibility; the Rachlin model fits empirical discounting data closely. Second, when compared with other available two-parameter discounting models, the Rachlin model has the advantage that unique best estimates for parameters are easy to obtain across a wide variety of potential discounting patterns. We focus this work on this second feature in the context of maximum likelihood, showing the relative ease with which the Rachlin model can be utilized compared with the extreme care that must be used with other models for discounting data, focusing on two illustrative cases that pass checks for data validity. Both of these features are demonstrated via a reanalysis of discounting data the authors have previously used for model selection purposes.
Asunto(s)
Conducta de Elección , Descuento por Demora , Modelos Psicológicos , Recompensa , Modelos EstadísticosRESUMEN
Behavioral economics has been a fruitful area of research in substance use. Mathematical descriptions of how individuals temporally discount the value of a commodity have been correlated with substance use and mathematical descriptions of drug consumption decreasing as a function of price (i.e., demand) predict maladaptive substance use. While there is a logical assumption that temporal factors affect demand for a drug, little has been done to merge these models. Thus, the purpose of this study was to combine models of discounting and demand, extending Howard Rachlin's work and contributions to novel areas of study. Data from 85 participants from Amazon Mechanical Turk (MTurk) who completed a hypothetical cigarette purchase task that included price of and delay to cigarettes were analyzed. Multilevel modeling was used to determine descriptive accuracy of combined additive and multiplicative models of discounting and demand. Of the discounting models used in conjunction with the exponentiated demand equation, the Rachlin hyperboloid best described the delay dimension of consumption. The multiplicative version of the Rachlin equation applied to both delay and price outperformed other models tested. Therefore, existing models of discounting and demand can be extended to modeling consumption data from complex multidimensional experimental arrangements.