Evolution of visual time throughout goal driven action learning
Timing is intimately woven into human cognition and behaviour, underscoring peoples ability of comprehending speech, playing instruments and competing in sports. Converging evidence suggests that our perceptual experience of time is grounded in our ability to control actions: time processing leverages motor control neural machinery, and perceived time is significantly distorted in proximity of action. However, the dynamic interplay between timing and action systems remains unexplored, particularly in goal-directed contexts where action control is gradually refined through practice. Through combined behavioural, neural and modelling approaches, we investigate how time processing gradually evolves as participants gain experience in goal-driven manual reaching actions, varying in terms of action-plan specificity. Participants judged brief visual durations while preparing hand movements aimed at visual targets displayed on a monitor. Subjective time expanded in the foreperiod preceding action onset, and this effect increased over trials, mirroring gradual improvements in action readiness as motor plans became more rapidly and efficiently deployed. Representation Similarity Analysis, integrating electroencephalographic and behavioural data, reveals that actions shape timing through independent mechanisms: planning specific behaviours shapes how duration information is written into timekeeping neural circuits as stimuli unfold (encoding). Parallely, more general aspects of motor engagement and anticipation shape how duration information is read-out from timing circuits following stimulus presentation (decoding). These findings highlight a dynamic, learning-driven coupling between perceptual time and motor control, where subjective time is recalibrated as goal-directed action preparation is optimized, shaped through independent time encoding and decoding mechanisms. Significance statementDespite lacking dedicated sensory and neural systems for duration, humans reveal a highly developed sense of time, for instance when noticing subtle tempo changes in music. We show that perceptual understanding of time is linked to the ability of learning and fine-tuning action: our internal metric of time shifts as action preparation processes are gradually refined, affecting how quickly behaviours are planned and executed. This interaction is mediated by independent neural processes affecting the encoding (online monitoring) and decoding (offline readout) of duration. These findings shift our understanding of timing, from a passive sensory readout to one that is actively constructed and finetuned through action learning, and provide a mechanistic account of neural processes linking action preparation to time processing