NASA TLX

Name: NASA TLX
Author: NASA

NASA

EVALUATED

Assessed for usability and quality

For:Researchers & AcademicsIndustry Professionals

Free

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App Summary

The NASA TLX app is a research tool that digitizes the gold-standard method for measuring subjective workload in operators of complex systems, from aircraft cockpits to laboratory settings. The tool's design is based on multi-year research that identified six core workload factors, and a subsequent review of 550 studies demonstrated its reliable sensitivity to changes in task demands. The associated research concludes that this multi-dimensional approach provides a sensitive and reliable estimate of workload, establishing it as a benchmark for human factors research.

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Detailed Description

Functionality & Mechanism

This application is the official mobile implementation of the NASA Task Load Index (TLX), developed by the NASA Ames Research Center. The system captures subjective workload ratings across six subscales: Mental, Physical, and Temporal Demand; Performance; Effort; and Frustration. It then computes a weighted average to derive a composite workload score. The interface facilitates rapid study setup via QR code integration and supports offline data collection in field environments, with results calculated directly on the device.

Evidence & Research Context

A general research article reviewing the instrument's use documented its application in over 550 studies, confirming its reliable sensitivity to workload variations across aviation, command and control, and simulations.
The instrument's design is detailed in a development paper, grounded in a multi-year program of 16 empirical studies that established its multi-dimensional structure for assessing workload.
The app extends the validated paper-and-pencil instrument, with associated research noting that computerized versions simplify data collection, storage, and analysis while enabling contextual field assessment.

Intended Use & Scope

This tool is intended for researchers, human factors specialists, and system designers for the quantitative assessment of subjective workload. The NASA TLX provides a perceived workload score and is not a direct measure of objective performance or physiological state. Findings require interpretation within specific task contexts and should be correlated with objective performance data where appropriate.

Studies & Publications

3 publications

Peer-reviewed research associated with this app.

Development/Design Paper

NASA TLX: software for assessing subjective mental workload

Cao et al. (2009) · Behavior Research Methods

Describes the research-driven development of this app

The NASA Task Load Index (TLX) is a popular technique for measuring subjective mental workload. It relies on a multidimensional construct to derive an overall workload score based on a weighted average of ratings on six subscales: mental demand, physical demand, temporal demand, performance, effort, and frustration level. A program for implementing a computerized version of the NASA TLX is described. The software version assists in simplifying collection, postprocessing, and storage of raw data. The program collects raw data from the subject and calculates the weighted (or unweighted) workload score, which is output to a text file. The program can also be tailored to a specific experiment using a simple input text file, if desired. The program was designed in Visual Studio 2005 and is capable of running on a Pocket PC with Windows CE or on a PC with Windows 2000 or higher. The NASA TLX program is available for free download.

Systematic Review/Meta-Analysis

NASA-Task Load Index (NASA-TLX); 20 Years Later

Hart et al. (2006) · Proceedings of the Human Factors and Ergonomics Society Annual Meeting

Research evidence supports NASA-TLX as a reliable and easy-to-use workload measurement tool across diverse domains.

NASA-TLX is a multi-dimensional scale designed to obtain workload estimates from one or more operators while they are performing a task or immediately afterwards. The years of research that preceded subscale selection and the weighted averaging approach resulted in a tool that has proven to be reasonably easy to use and reliably sensitive to experimentally important manipulations over the past 20 years. Its use has spread far beyond its original application (aviation), focus (crew complement), and language (English). This survey of 550 studies in which NASA-TLX was used or reviewed was undertaken to provide a resource for a new generation of users. The goal was to summarize the environments in which it has been applied, the types of activities the raters performed, other variables that were measured that did (or did not) covary, methodological issues, and lessons learned

In the Media

TLX @ NASA Ames - NASA TLX App

NASA's Ames Research Center developed the Official NASA Task Load Index (TLX) app to modernize workload assessment research, replacing the gold-standard pencil and paper questionnaires used since the 1980s. "The Official NASA TLX app addresses a significant backlog of pent up demand from researchers looking for a workload measurement solution that integrates with their modern computer/research environments," said Dr. Brian Gore, TLX project lead at Ames. The free iOS application launched on February 15 and is available worldwide without requiring NASA permission.

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