Skip to main content
Version: v2.2.0

nasa-tlx

The NASA-TLX is a widely used subjective workload assessment tool. It consists of six subscales: Mental Demand, Physical Demand, Temporal Demand, Performance, Effort, and Frustration. The NASA-TLX is designed to assess the perceived workload of a task and is commonly used in human factors and ergonomics research. We provide a component of the NASA-TLX itself, and a sequence that includes a source of load evaluation. The source of load evaluation is based on the pairwise weighting procedure described in the NASA-TLX manual.

Reference​

Reference

Hart, Sandra G., and Lowell E. Staveland. "Development of NASA-TLX (Task Load Index): Results of empirical and theoretical research." Advances in psychology. Vol. 52. North-Holland, 1988. 139-183.

DOI: 10.1016/S0166-4115(08)62386-9

Available Components​

  • nasa-tlx
  • source-of-load

Available Sequences​

  • nasa-tlx-with-source-of-load-evaluation

Additional Description​

Source of Workload Evaluation (Pairwise Weighting Procedure)​

Reference: NASA TLX manual (Section 2.2)

This step of the NASA-TLX assesses the relative importance of different factors that contribute to a person's experience of workload during a task. Rather than assuming all workload components are equally important, this procedure captures individual differences in how workload is perceived.

Participants are presented with 15 pairwise comparisons between the six NASA-TLX subscales:

  • Mental Demand
  • Physical Demand
  • Temporal Demand
  • Performance
  • Effort
  • Frustration

For each pair, participants are asked to select the factor that contributed more to their workload experience in the given task.

How It Works​

Each chosen subscale earns one point (a "tally mark").

After 15 comparisons, each subscale has a weight from 0 to 5.

These weights reflect the participant's personal weighting of each workload dimension.

How to Use the Result​

After task performance, participants also rate the magnitude (0–100) of each of the six subscales.

For each subscale: Adjusted Score = Raw Rating × Weight

The overall workload score is calculated by summing all adjusted scores and dividing by 15: Overall Workload = Σ(Adjusted Scores) ÷ 15

This weighted workload score accounts for both perceived intensity and individual prioritization, improving sensitivity and personalization in workload analysis.