Darinka Trübutschek¹, Ilona Vieten², Caspar M. Schwiedrzik^3,4,5, Lucia Melloni; ¹Research Group Neural Circuits, Consciousness, and Cognition, Max Planck Institute for Empirical Aesthetics, Grüneburgweg 14, 60322 Frankfurt/Main, Germany, ²Department of Epileptology, University Medical Center Bonn, Germany, ³Cognitive Neurobiology, Research Center One Health Ruhr, University Alliance Ruhr, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Universitätsstraße 150, 44801 Bochum, Germany, ⁴Neural Circuits and Cognition Lab, European Neuroscience Institute Göttingen – A Joint Initiative of the University Medical Center Göttingen and the Max Planck Institute for Multidisciplinary Sciences, Grisebachstraße 5, 37077 Göttingen, Germany, ⁵Perception and Plasticity Group, German Primate Center – Leibniz Institute for Primate Research, Kellnerweg 4, 37077 Göttingen, Germany, ⁶Predictive Brain Department, Research Center One Health Ruhr, University Alliance Ruhr, Ruhr-Universität Bochum, ⁷Department of Neurology, New York University Grossman School of Medicine, New York, New York, USA

According to the Bayesian brain hypothesis, perception integrates sensory inputs with prior information to generate coherent interpretations of the environment. Such prior information may originate from perceptual history, as demonstrated by serial dependence - an automatic process thought to stabilize perception by biasing it toward recently encountered stimuli. However, priors may also emerge from task-relevant information held in working memory (WM). While both sources of prior information seem critical for perception, how these automatic, history-based biases interact with top-down, WM-driven priors remains unknown. We investigated this question in a task combining a serial dependence paradigm with concurrent WM demands. Twenty-two participants maintained two orientation templates in WM for several minutes. Meanwhile, they performed repeated trials in which one of the two templates was cued as currently task-relevant, followed by the presentation of a briefly displayed Gabor patch. Participants first reproduced the patch's orientation and then judged whether it was rotated clockwise or counterclockwise relative to the active template. This orientation adjustment task enabled us to assess the influence of three priors on perceptual judgments: the previous trial’s stimulus (serial dependence), the currently active template, and the currently latent (uncued) template. Our results revealed that serial dependence was absent when concurrent active and latent WM representations were engaged. Instead, participants’ adjustment responses were attracted toward the active template, particularly when the angular distance fell between 30° and 60°. Latent WM templates influenced perception in only a subset of participants, with weaker and sometimes repulsive effects. These findings suggest that perception operates under a dynamic hierarchy of priors, with task-relevant WM representations overriding sensory history and latent WM priors. This hierarchy may balance perceptual stability and flexibility, enabling the brain to dynamically adapt sensory processing to meet task demands.

Acknowledgements: This work was supported in part by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 101023805 to D. T.