NASATLX

NASA-TLX (NASA Task Load Index) is a widely used subjective workload assessment tool created by Hart and Staveland at NASA Ames in 1988. It measures perceived workload associated with a task, system, or operation.

The instrument comprises six subscales: mental demand, physical demand, temporal demand, performance, effort, and frustration level. After a task, respondents rate each subscale on a 0 to 100 scale, reflecting their perceived workload along that dimension.

Two scoring approaches are commonly used. The original NASA-TLX uses a weighted combination of the six subscale ratings, with dimensional weights obtained through a pairwise comparison procedure in which each pair of dimensions is compared to determine relative importance (there are 15 comparisons). The overall workload score is the weighted sum of the six ratings. A simpler, unweighted method averages the six ratings to yield a single workload index.

NASA-TLX is applied across domains including aviation, driving, healthcare, military, industrial engineering, and human-computer interaction to assess workload changes due to task design, automation, or training. Strengths include sensitivity to different workload components and ease of administration; limitations involve subjectivity, context sensitivity, and potential biases in self-report.