HOW IS COGNITIVE WORKLOAD MEASURED?
There exist only a few ways to measure cognitive workload. Until fairly recently, the available choices were to rely on external behavioral outcomes or on the individual’s own impression of workload. With the former, one had to assume that successful performance mirrored workload to the extent that poor performance was a good indicator of workload. With the latter, one had to assume that an individual could accurately identify and report changes in cognitive workload. Both assumptions have some problems.
Many researchers today turn instead to approaches that are physiological in origin. These physiological measurements range from changes in galvanic skin response to changes in heart rate to changes in brain signals. With advances in technology, physiological metrics are more readily available and overcome the obstacles inherent in self report measurement or performance outcomes.
What do we want in a physiological indicator of cognitive workload? Four important requirements are:
- It should reflect what’s going on in the individual’s brain.
- It should produce continuous estimates in real time.
- It should be easily measured and non-invasive for the individual.
- It should work in the real world as well as in the research laboratory.