Wiebke Nörenberg^1,2 (wiebke.noerenberg@hu-berlin.de), Pascal Mamassian³, Martin Rolfs^1,2,4; ¹Humboldt-Universität zu Berlin, ²Berlin School of Mind and Brain, ³École Normale Supérieure, PSL University, CNRS, Paris, ⁴Cluster of Excellence ‘Science of Intelligence’, TU Berlin

Temporal recalibration allows the perceptual system to adjust perceived timing when systematic delays arise between actions and their sensory consequences. This process extends to saccadic eye movements, but it is unclear whether the resulting adaptation reflects a simple decision-criterion shift or a genuine perceptual change. If the former is true, observers should doubt their timing judgements. We developed a paradigm to dissociate these two possibilities by jointly measuring how temporal recalibration reshapes the perceived window of saccade execution and observers’ metacognitive access to it. Observers executed horizontal saccades across a dynamic noise background while brief, high-contrast, horizontally-extended Gaussian ellipses (4 ms “flash”) were presented at various times relative to movement onset. In a matched replay session, observers maintained fixation while horizontal background movements and flashes reproduced the kinematics and timing of each observer’s own saccades, reproducing the same stimulus–movement relations. In 60% of trials per block, we introduced systematic temporal delays by presenting the flash predominantly either immediately (20 ms) or with a delay (80 ms) after movement onset, while the remaining trials sampled a wide range of timings (±250 ms around movement onset). Reports were only collected in this latter subset. Observers first judged simultaneity of flash and movement. They then rated whether their confidence was ‘higher’ or ‘lower’ than the average across the experiment so far. In the saccade sessions, reported simultaneity shifted to later times when flashes were systematically delayed. Participants’ confidence in the accuracy of their reports remained stable across delay conditions, thereby denoting a genuine perceptual shift in stimulus timing rather than a shift in decision criterion. Interestingly, metacognitive sensitivity was reduced when flashes were perceived simultaneously with the saccade. In the replay condition, neither simultaneity reports nor metacognitive sensitivity were affected by the systematic delay, indicating that the effect requires a motor act.

Acknowledgements: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. [865715 – VIS-A-VIS]).