Presentation
Design Matters: Scale Design and Rounding Ratings Impacts NASA-TLX Results
SessionPoster Session 1
DescriptionThe NASA Task Load Index (NASA-TLX) is a widely used subjective measure of Mental Workload (MWL). However, its visual design characteristics and post-collection processing methods (rounding) lack standardization in official documentation and implementation in human factors studies. Similarly, rounding methods are not uniformly applied. These issues may bias workload measurement results. A secondary data analysis from a previous, within-subjects study was conducted to test whether different response format designs (Knob, Slider, or Ask type) resulted in different workload ratings across the six TLX dimensions. Friedman tests showed significant differences between the results produced for each response format, except Effort, both on rounded and unrounded ratings. Further, Wilcoxon Signed Ranks tests revealed significant differences between the rounded and unrounded data distributions for each sub-scale. Finally, parametric comparisons of the data between different task-difficulty conditions suggest that the experimental findings can be influenced by the response format used to collect ratings. Overall, both rounding and response format design can bias NASA-TLX ratings. Therefore, standard practices should be further researched and implemented to avoid these effects.
Event Type
Poster
TimeTuesday, October 14th5:30pm - 6:30pm CDT
LocationRiverside East
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