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Shih-Wei Wu, Laurence Maloney; Neural correlates of value and probability in decision under risk and in an equivalent visuo-motor task. Journal of Vision 2008;8(6):545. doi: 10.1167/8.6.545.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose. In visuo-motor tasks, it has been shown that humans come remarkably close to that expected of an ideal observer or mover. Research in economic decision under risk, on the contrary, repeatedly demonstrated large deviations from optimality. The sharp contrast in performance between visuo-motor tasks and economic decision tasks revealed modular specificity in the neural systems representing decision variables, i.e., value and probability. However, it is not clear whether modular specificity arises from a common neural system that captures the unique, modality specific representations of decision variables or alternatively, from separate systems representing those variables unique to the kind of decision task the chooser is facing. Method. We investigated the neural correlates of value and probability using fMRI and by separately estimating the distortions of value and probability in economic decision task and its equivalent visuo-motor task. There were 3 sessions in the experiment. In the first session, subjects performed rapid pointing to a rectangular target varying in size (384 trials). For each subject, his/her motor variability was estimated at the asymptotic level for the purpose of creating motor configurations mathematically equivalent to a single lottery. In the second and third session, subjects faced both economic decision tasks and equivalent visuo-motor tasks. The distortions of value and probability were estimated separately based on the subject's choice in the visuo-motor task and the economic decision task. Subjects did the third session in the MRI scanner. Results. 4 naïve subjects participated in the experiment. We found that activity in the striatum, the cingulate gyrus, the superior and the middle frontal gyrus tracked the distortions of probability for both the visuo-motor task and the economic task. We take this as initial evidence to suggest that there is a common circuitry representing subjective probability that is independent of decision modality.
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