Confirmation Bias through Selective Overweighting of Choice-Consistent Evidence

Bharath Chandra Talluri*, Anne E. Urai, Konstantinos Tsetsos, Marius Usher, Tobias H. Donner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


People's assessments of the state of the world often deviate systematically from the information available to them [1]. Such biases can originate from people's own decisions: committing to a categorical proposition, or a course of action, biases subsequent judgment and decision-making. This phenomenon, called confirmation bias [2], has been explained as suppression of post-decisional dissonance [3, 4]. Here, we provide insights into the underlying mechanism. It is commonly held that decisions result from the accumulation of samples of evidence informing about the state of the world [5–8]. We hypothesized that choices bias the accumulation process by selectively altering the weighting (gain) of subsequent evidence, akin to selective attention. We developed a novel psychophysical task to test this idea. Participants viewed two successive random dot motion stimuli and made two motion-direction judgments: a categorical discrimination after the first stimulus and a continuous estimation of the overall direction across both stimuli after the second stimulus. Participants’ sensitivity for the second stimulus was selectively enhanced when that stimulus was consistent with the initial choice (compared to both, first stimuli and choice-inconsistent second stimuli). A model entailing choice-dependent selective gain modulation explained this effect better than several alternative mechanisms. Choice-dependent gain modulation was also established in another task entailing averaging of numerical values instead of motion directions. We conclude that intermittent choices direct selective attention during the evaluation of subsequent evidence, possibly due to decision-related feedback in the brain [9]. Our results point to a recurrent interplay between decision-making and selective attention. Committing to a categorical choice biases subsequent decision-making, a phenomenon called confirmation bias. Talluri, Urai et al. developed a new behavioral task to probe into the underlying mechanism. They find that choices selectively increased the weighting of choice-consistent evidence on subsequent decisions, in a way resembling attention.

Original languageEnglish
Pages (from-to)3128-3135.e8
JournalCurrent Biology
Issue number19
StatePublished - 8 Oct 2018


FundersFunder number
Horizon 2020 Framework Programme658581
Deutscher Akademischer Austauschdienst
Deutsche ForschungsgemeinschaftDO 1240/3-1, DO 1240/2-1, SFB 936/A7


    • attention
    • computational model
    • decision-making
    • human
    • numerical cognition
    • perception
    • psychophysics


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