Magnitude-sensitive reaction times reveal non-linear time costs in multi-alternative decision-making

• Published in: PLoS computational biology Vol. 18; no. 10; p. e1010523
• Main Authors: Marshall, James A. R., Reina, Andreagiovanni, Hay, Célia, Dussutour, Audrey, Pirrone, Angelo
• Format: Journal Article
• Language: English
• Published: San Francisco Public Library of Science 03.10.2022; PLOS; Public Library of Science (PLoS)
• Subjects: Analysis; Biology and Life Sciences; Choice Behavior; Computer and Information Sciences; Computer simulation; Computer-generated environments; Cost analysis; Costs; Costs and Cost Analysis; Decision analysis; Decision Making; Experiments; Food; Foraging behavior; Human subjects; Humans; Life Sciences; Methods; Neurosciences; Optimization; Physical Sciences; Reaction Time; Reward; Sensitivity; Slime molds; Social Sciences; Theoretical analysis; United Kingdom
• ISSN: 1553-7358; 1553-734X; 1553-7358
• DOI: 10.1371/journal.pcbi.1010523

Optimality analysis of value-based decisions in binary and multi-alternative choice settings predicts that reaction times should be sensitive only to differences in stimulus magnitudes, but not to overall absolute stimulus magnitude. Yet experimental work in the binary case has shown magnitude sensitive reaction times, and theory shows that this can be explained by switching from linear to multiplicative time costs, but also by nonlinear subjective utility. Thus disentangling explanations for observed magnitude sensitive reaction times is difficult. Here for the first time we extend the theoretical analysis of geometric time-discounting to ternary choices, and present novel experimental evidence for magnitude-sensitivity in such decisions, in both humans and slime moulds. We consider the optimal policies for all possible combinations of linear and geometric time costs, and linear and nonlinear utility; interestingly, geometric discounting emerges as the predominant explanation for magnitude sensitivity.