Eye and Gaze Behavior During Human Disassembly Procedures: Effects of Task Conditions and Process Dynamics

Manual disassembly is a key process in remanufacturing and circular-economy systems, yet it is often characterized by uncertainty, varying product conditions and non-standardized action sequences. Eye tracking provides a process-oriented methodology for examining how such tasks are visually guided, with implications for human behavior analysis, operator support, and automation design. The present study investigated the potential of specific eye and gaze metrics to reflect differences in task condition and process dynamics during human disassembly. These were analyzed using a dimension-based mixed-effect modeling approach, accounting for task condition, handcraft skill levels, and task duration across repeated observations within participants, addressing four dimensions: visual attention allocation, cognitive workload, scanpath structure, and gaze organization. The results showed that increased task uncertainty was most associated with shorter fixation durations, higher fixation rates, larger pupil diameters, and higher revisit rates, indicating intensified visual sampling, increased cognitive workload, and repeated checking behavior. No robust differences were observed between skill levels. A longer task duration, as an indirect proxy of less routine-like execution, was primarily reflected in fixation dynamics and scanpath structure, rather than in entropy or workload measures. The findings demonstrate the sensitivity of eye and gaze metrics to task uncertainty and process dynamics in disassembly.