title: A dual-process approach to exploring the role of delay discounting in obesity.
abstract: Delay discounting of financial rewards has been related to overeating and obesity. Neuropsychological evidence supports a dual-system account of both discounting and overeating behaviour where the degree of impulsive decision making is determined by the relative strength of reward desire and executive control. A dual-parameter model of discounting behaviour is consistent with this theory. In this study, the fit of the commonly used one-parameter model was compared to a new dual-parameter model for the first time in a sample of adults with wide ranging BMI. Delay discounting data from 79 males and females (males=26) across a wide age (M=28.44years (SD=8.81)) and BMI range (M=25.42 (SD=5.16)) was analysed. A dual-parameter model (saturating-hyperbolic; Doya, [Doya (2008) ]) was applied to the data and compared on model fit indices to the single-parameter model. Discounting was significantly greater in the overweight/obese participants using both models, however, the two parameter model showed a superior fit to data (p<0.0001). The two parameters were shown to be related yet distinct measures consistent with a dual-system account of inter-temporal choice behaviour. The dual-parameter model showed superior fit to data and the two parameters were shown to be related yet distinct indices sensitive to differences between weight groups. Findings are discussed in terms of the impulsive reward and executive control systems that contribute to unhealthy food choice and within the context of obesity related research.
authors.affiliation: Department of Psychology, College of Human and Health Sciences, Swansea University, Singleton Park, Swansea, UK. Electronic address: m.j.price@swansea.ac.uk.
authors.forename: Menna
authors.initials: M
authors.lastname: Price
authors.affiliation: School of Psychology, University of Birmingham, Edgbaston, Birmingham, UK.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Higgs
authors.affiliation: Department of Economics, College of Business and Economics, Swansea University, Bay Campus, Swansea, UK.
authors.forename: James
authors.initials: J
authors.lastname: Maw
authors.affiliation: Department of Psychology, College of Human and Health Sciences, Swansea University, Singleton Park, Swansea, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D065786:Delay Discounting / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009765:Obesity / Q000503:physiopathology / Q000523:psychology*; D011795:Surveys and Questionnaires; D013997:Time Factors; D055815:Young Adult
keywords: Delay discounting; Dual-process; Model; Obesity; Two-parameter