Degenerate boundaries for multiple-alternative decisions

Baker, Sophie-Anne, Griffith, Thom and Lepora, Nathan F. 2022. Degenerate boundaries for multiple-alternative decisions. Nature Communications 13 (1) , 5066. 10.1038/s41467-022-32741-y

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Abstract

Integration-to-threshold models of two-choice perceptual decision making have guided our understanding of human and animal behavior and neural processing. Although such models seem to extend naturally to multiple-choice decision making, consensus on a normative framework has yet to emerge, and hence the implications of threshold characteristics for multiple choices have only been partially explored. Here we consider sequential Bayesian inference and a conceptualisation of decision making as a particle diffusing in n-dimensions. We show by simulation that, within a parameterised subset of time-independent boundaries, the optimal decision boundaries comprise a degenerate family of nonlinear structures that jointly depend on the state of multiple accumulators and speed-accuracy trade-offs. This degeneracy is contrary to current 2-choice results where there is a single optimal threshold. Such boundaries support both stationary and collapsing thresholds as optimal strategies for decision-making, both of which result from stationary representations of nonlinear boundaries. Our findings point towards a normative theory of multiple-choice decision making, provide a characterisation of optimal decision thresholds under this framework, and inform the debate between stationary and dynamic decision boundaries for optimal decision making.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Psychology
Publisher:	Nature Research
ISSN:	2041-1723
Date of First Compliant Deposit:	2 September 2025
Date of Acceptance:	15 August 2022
Last Modified:	02 Sep 2025 09:30
URI:	https://orca.cardiff.ac.uk/id/eprint/180768

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