title: Decisions reduce sensitivity to subsequent information.
abstract: Behavioural studies over half a century indicate that making categorical choices alters beliefs about the state of the world. People seem biased to confirm previous choices, and to suppress contradicting information. These choice-dependent biases imply a fundamental bound of human rationality. However, it remains unclear whether these effects extend to lower level decisions, and only little is known about the computational mechanisms underlying them. Building on the framework of sequential-sampling models of decision-making, we developed novel psychophysical protocols that enable us to dissect quantitatively how choices affect the way decision-makers accumulate additional noisy evidence. We find robust choice-induced biases in the accumulation of abstract numerical (experiment 1) and low-level perceptual (experiment 2) evidence. These biases deteriorate estimations of the mean value of the numerical sequence (experiment 1) and reduce the likelihood to revise decisions (experiment 2). Computational modelling reveals that choices trigger a reduction of sensitivity to subsequent evidence via multiplicative gain modulation, rather than shifting the decision variable towards the chosen alternative in an additive fashion. Our results thus show that categorical choices alter the evidence accumulation mechanism itself, rather than just its outcome, rendering the decision-maker less sensitive to new information.
authors.affiliation: School of Psychology, Tel-Aviv University, Tel-Aviv, Israel The Cohn Institute for the History and Philosophy of Science and Ideas, Tel-Aviv University, Tel-Aviv, Israel zoharbronfman@gmail.com.
authors.forename: Zohar Z
authors.initials: ZZ
authors.lastname: Bronfman
authors.affiliation: School of Psychology, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Noam
authors.initials: N
authors.lastname: Brezis
authors.affiliation: School of Psychology, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Rani
authors.initials: R
authors.lastname: Moran
authors.affiliation: Department of Experimental Psychology, University of Oxford, Oxford, UK.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Tsetsos
authors.affiliation: Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands Amsterdam Brain & Cognition, University of Amsterdam, Amsterdam, The Netherlands Bernstein Center for Computational Neuroscience, Charité-Universitätsmedizin, Berlin, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Donner
authors.affiliation: School of Psychology, Tel-Aviv University, Tel-Aviv, Israel Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel marius@post.tau.ac.il.
authors.forename: Marius
authors.initials: M
authors.lastname: Usher
mesh_terms: D000328:Adult; D002755:Choice Behavior; D003657:Decision Making; D006801:Humans; D011336:Probability; D055815:Young Adult
keywords: changes of mind; confirmation bias; numerical averaging; perceptual decision-making