NASA Task Load Index (TLX)

Developed by: NASA Human Systems Integration Division

Description: NASA Task Load Index (TLX) is a subjective workload assessment tool available as an iOS app for use by any person or organization (worldwide). It allows users to perform subjective workload assessments on operator(s) working with various human-machine interface systems. Originally developed as a paper and pencil questionnaire by NASA Ames Research Center’s (ARC) Sandra Hart in the 1980s, NASA TLX has become the gold standard for measuring subjective workload across a wide range of applications.

By incorporating a multi-dimensional rating procedure, NASA TLX derives an overall workload score based on a weighted average of ratings on six subscales:

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