Perceptual Fluctuations – FLUCTUAT

Do we all see the world the same way? This age-old philosophical question remains largely unanswered. Recent research has made this problem even more complex, showing that perception varies not only from person to person but also from moment to moment—even when looking at the same image.

The FLUCTUAT project tackles this problem from a fresh new perspective, leveraging one of the most influential paradigms to emerge in the past decade of research: serial dependence, whereby perceptual decisions are influenced by the recent history of events. Serial dependence typically manifests when sensory input is uncertain and exhibits remarkable inter-individual variability as well as fluctuations within the same person over time. We combine these observations into a framework where perceptual decisions emerge from the interaction between exogenous factors, such as changes in the environment, and endogenous factors, such as fluctuations in internal states, and aim to focus on this interaction for the first time in depth.

Over four years, the project will revolve around four main objectives. First, we will assess general and individual-specific traits of serial dependence across different tasks and stimuli. Second, we will investigate how exogenous and endogenous states interact to shape the influence of prior events in perceptual decision-making. Third, we will characterize the neural correlates of these phenomena. Finally, we will develop a computational model capable of capturing the dynamic interaction between external and internal factors, aiming at an unmatched explanatory power at the individual level.

The overarching goal is to achieve an unprecedented understanding of what makes each individual perceptual experience unique—a question that has persisted for centuries and remains critical for advancing future research in perception and cognition. Beyond fundamental science, this work has long-term implications for clinical research, as abnormal serial dependence has recently been linked to neuropsychiatric conditions.