Matthew FS Rushworth

15 mai 2014

Department of Experimental Psychology, University of Oxford, UK

Foraging and deciding between multiple choices

invité par Sabrina Ravel

Abstract : Many investigations of the neural mechanisms have focused on binary decisions – choosing between two options. In a recent investigation we used a biophysical model of decision-making to explore how choices representations might change when decisions when there are three potential options. The model predicted that it would be more difficult to choose accurately between two options with similar values in the presence of a third alternative with a low value rather than a high value. Human subject choices conformed to this prediction as did fMRI-recorded value difference signals in the ventromedial prefrontal cortex (vmPFC). Individual differences in the modulation of vmPFC signals predicted individual differences in the degree to which subjects’ decisions were modified by the presence of irrelevant alternatives. By contrast, another brain area, the dorsal anterior cingulate (ACC), is able to track the average values of several possible alternative choices. The ACC appears to code for the value of switching away from taking the current default choice in a manner that is predicted by theories of optimal foraging in behavioural ecological investigations. In addition we show that the same ACC region tracks dynamic changes in how risk prone or risk averse a person should be. Again such tracking is predicted by models of optimal foraging in behavioural ecological investigations.

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