How does fatigue affect cognitive load through emotion regulation strategies in unmanned forklift scenarios?

Objectives. Operators monitoring unmanned forklifts may still experience fatigue despite relatively low physical demands, which can increase cognitive load and pose safety risks. Emotion regulation may buffer fatigue-related impairment, but the mechanisms remain unclear, particularly for two emotion regulation strategies: cognitive reappraisal and expressive suppression. This study examined whether emotion regulation strategies mediate the association between multidimensional fatigue and cognitive load in unmanned forklift monitoring. Methods. Sixty-five participants completed a monitoring task involving unmanned forklift trucks and reported fatigue (task engagement, distress, worry), emotion regulation strategies (cognitive reappraisal, expressive suppression) and cognitive load via self-report scales. Results. Structural equation modeling analysis revealed that higher levels of task engagement - serving as an indicator of fatigue - were associated with higher self-reported propensities for cognitive reappraisal. Moreover, individuals who more frequently employed a cognitive reappraisal strategy reported lower levels of cognitive load. Cognitive reappraisal significantly mediated the relationship between task engagement and cognitive load. Through fuzzy-set qualitative comparative analysis, this study identified four distinct configurations that reduce cognitive load. Conclusion. The findings underscore the importance of emotion regulation for understanding cognitive demands in unmanned forklift scenarios. Future research could expand intervention approaches to better support operators' psychological well-being in such settings.