The National Aviation and Space Agency Task Load Index (NASA-TLX): Does it Need Updating?

The NASA-TLX is arguably the most widely used self-report measure of workload in the field of Human Factors and Ergonomics. Previous research utilizing factor analysis has indicated it may not actually be a good unitary measure of workload. In the present study, we have modified two of the original six items, Frustration and Performance, to better reflect workload by replacing them with Emotional Demand and Performance Monitoring Demand items. Confirmatory factor analyses indicate the new scale is an improvement but Physical Demand should also be considered for removal; this results in a five-item measure of mental workload, not overall task workload, as physical demands may not be meaningfully combinable with cognitive demands.