Development and validation of a simulation workload measure: the simulation task load index (SIM-TLX)

Virtual reality (VR) simulation offers significant potential for human factors training as it provides a novel approach which enables training in environments that are otherwise dangerous, impractical or expensive to simulate. While VR training has been adopted in many environments, such as heavy industry, surgery and aviation, there remains an inadequate understanding of how virtual simulations impact cognitive factors. One such factor, which needs careful consideration during the design of VR simulations, is the degree of mental or cognitive load experienced during training. This study aimed to validate a newly developed measure of workload, based on existing instruments (e.g. the NASA-TLX), but tailored to the specific demands placed on users of simulated environments. While participants completed a VR puzzle game, a series of experimental manipulations of workload were used to assess the sensitivity of the new instrument. The manipulations affected the questionnaire subscales (mental demands; physical demands; temporal demands; frustration; task complexity; situational stress; distraction; perceptual strain; task control; presence) as predicted in all cases (ps < .05), except for presence, which displayed little relationship with other aspects of task load. The scale was also found to have good convergent validity with an alternate index of task load. The findings support the sensitivity of the new instrument for assessing task load in virtual reality. Overall, this study contributes to the understanding of mental workload in simulated environments and provides a practical tool for use in both future research and applications in the field.