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The NASA-TLX is a subjective workload measure that uses six dimensions to assess mental workload: mental demand, physical demand, temporal demand, performance, effort, and frustration. Users may respond using this tool during the task or after the task is completed. Below you will find an example of how the NASA TLX can be applied.
Example
Research Question: How much workload is involved while playing a song on the ukulele?
The participant was asked to complete the NASA-TLX after playing a song on the ukulele using 7-point scales that measure mental demand, physical demand, temporal demand, performance, effort, and frustration level.
The user was asked to verbalize any notable details about their responses to each rating they provided. Below are the descriptions that were collected.
Mental demand of playing involved mostly things associated with memory: timing of switching my fingers on different chords, remembering what chords to play, and remembering what fingers go on each string.
Physical Demand: Since I had not played in a while, I had to remember the amount of pressure I needed on the strings so that the correct sound came out. I also had to remember to position my fingers precisely on the correct strings so that they don’t touch neighboring strings.
Temporal Demand: I did not use a metronome; however, I did feel that I was rushing the tempo during the song.
Performance: I think I was successful in playing the song in the sense that I played the correct notes. But in terms of quality, I don’t think I was as successful. For example, I stopped and restarted a few times. I also played a lot of “buzz notes” where I unintentionally was touching other strings I wasn’t supposed to or not putting enough pressure on the correct strings. My goal wasn’t for quality in the task, but rather the successful memorization of finger placement and strumming pattern. Some aspects of the task were effortful (i.e., certain chord switches) and some weren’t (i.e., playing C only uses one finger). For that reason, I found this question more difficult to answer.
My frustration level fell in the middle of the scale, with points in which I was relaxed and enjoyed playing and other points where I was irritated at the placement of my fingers.
Things to remember:
If the participant does not understand the terminology used in the NASA-TLX, you may not receive accurate responses. If participants are frustrated with the task, they may just answer with high workload across all demands.
Although the generality is useful in some regards, the NASA-TLX can also be too general with its questions. For instance, there may be some points in the task where temporal demand is very high and others where it's very low.
There are variations of points systems to use on the scale (e.g., 100-point, 7-point).
Pros:
Relatively easy to deliver and use
You can use it for a variety of different tasks
Cons:
The questions can be too general
Those that are not familiar with the terminology may not answer accurately.
If completed retrospectively, participants may forget information about the task
References:
Hart, S.G., & Staveland, L.E. (1988). Development of NASA-TLX (Task Load Index): Results of Empirical and Theoretical Research. Advances in psychology, 52, 139-183.
Rubio, S., Díaz, E., Martín, J., & Puente, J. M. (2004). Evaluation of subjective mental workload: A comparison of SWAT, NASA-TLX, and workload profile methods. Applied Psychology: An International Review, 53(1), 61–86. https://doi.org/10.1111/j.1464-0597.2004.00161.x
The NASA TLX Tool: Task Load Index. (2019). TLX @ NASA Ames - NASA TLX Paper/Pencil Version. National Aeronautics And Space Administration. https://humansystems.arc.nasa.gov/groups/tlx/tlxpaperpencil.php
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