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The expectancy valence model of the Iowa Gambling Task: Can it produce reliable estimates for individuals?


Humphries, MA and Bruno, R and Karpievitch, Y and Wotherspoon, S, The expectancy valence model of the Iowa Gambling Task: Can it produce reliable estimates for individuals?, Journal of Mathematical Psychology, 64-65 pp. 17-34. ISSN 0022-2496 (2015) [Refereed Article]

Copyright Statement

2014 Elsevier Inc.

DOI: doi:10.1016/


The Expectancy Valence Model (EVM) of the Iowa Gambling Task (IGT) is commonly used in studies to identify the underlying psychological processes responsible for decision making deficits.We show the EVM does not provide clear information about decision making processes at the individual level by fitting the EVM, with individual random effects, to a sample of participants from various drug using populations using Bayesian techniques and to a sample of participants who complete the IGT multiple times. In particular, we show that the individual-level parameter estimates from the model may be bi-modally distributed and hence are inherently ambiguous and have little psychological significance.In an attempt to increase the validity of individual-level parameter estimates, we also considered a 2-parameter version of the EVM in which the consistency parameter was held constant. In the 2-parameter implementation of the EVM, results were clearer and more easily interpretable than when using the traditional EVM.

Item Details

Item Type:Refereed Article
Keywords:2-parameter EVM, Bayesian estimation, decision making, expectancy valence model (EVM), individual performance, Iowa gambling task (IGT), MCMC
Research Division:Mathematical Sciences
Research Group:Applied mathematics
Research Field:Applied mathematics not elsewhere classified
Objective Division:Health
Objective Group:Public health (excl. specific population health)
Objective Field:Public health (excl. specific population health) not elsewhere classified
UTAS Author:Humphries, MA (Mrs Melissa Humphries)
UTAS Author:Bruno, R (Associate Professor Raimondo Bruno)
UTAS Author:Karpievitch, Y (Dr Yuliya Karpievitch)
UTAS Author:Wotherspoon, S (Dr Simon Wotherspoon)
ID Code:98343
Year Published:2015
Web of Science® Times Cited:4
Deposited By:Psychology
Deposited On:2015-02-12
Last Modified:2017-11-01

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