title: A neural mechanism underlying failure of optimal choice with multiple alternatives.
abstract: Despite widespread interest in neural mechanisms of decision-making, most investigations focus on decisions between just two options. Here we adapt a biophysically plausible model of decision-making to predict how a key decision variable, the value difference signal-encoding how much better one choice is than another-changes with the value of a third, but unavailable, alternative. The model predicts a surprising failure of optimal decision-making: greater difficulty choosing between two options in the presence of a third very poor, as opposed to very good, alternative. Both investigation of human decision-making and functional magnetic resonance imaging-based measurements of value difference signals in ventromedial prefrontal cortex (vmPFC) bore out this prediction. The vmPFC signal decreased in the presence of low-value third alternatives, and vmPFC effect sizes predicted individual variation in suboptimal decision-making in the presence of multiple alternatives. The effect contrasts with that of divisive normalization in parietal cortex.
authors: Department of Experimental Psychology, University of Oxford, Oxford, UK.
authors: Bolton K H
authors: BK
authors: Chau
authors: Department of Experimental Psychology, University of Oxford, Oxford, UK.
authors: Nils
authors: N
authors: Kolling
authors: FMRIB Centre, University of Oxford, John Radcliffe Hospital, Oxford, UK.
authors: Laurence T
authors: LT
authors: Hunt
authors: Department of Experimental Psychology, University of Oxford, Oxford, UK.
authors: Mark E
authors: ME
authors: Walton
authors: 1] Department of Experimental Psychology, University of Oxford, Oxford, UK. [2] FMRIB Centre, University of Oxford, John Radcliffe Hospital, Oxford, UK.
authors: Matthew F S
authors: MF
authors: Rushworth
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D003657:Decision Making / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D016571:Neural Networks, Computer; D017397:Prefrontal Cortex / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D055815:Young Adult