Metric · Cognitive load
Mental effort
What it tells you
How hard people had to think to use the AI feature. In the KU Leuven review, the size and structure of an explanation were found to influence it.
How, in 5 minutes
Two items adapted from the NASA Task Load Index (NASA-TLX), mental demand and frustration, on a 1 to 7 scale after the task, plus time on task from the logs.
Benchmark
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Questionnaire items
- How mentally demanding was the task? (1 to 7)
- How frustrated did you feel during the task? (1 to 7)
Answer on a 1 to 7 scale from strongly disagree to strongly agree unless the item states its own scale. The ULTRA team wrote or adapted these items for the kits and has not checked their reliability, so report them as ULTRA kit items and name any questionnaire they were adapted from.
Log events
task_started {task}task_completed {task, duration_ms}Pairs with
Research side · the property behind this metric
Property
References
- Hart and Staveland 1988, NASA-TLX.
- Donoso-Guzmán et al. 2025: five of the reviewed studies used the standardised NASA-TLX.