Various studies have demonstrated how low workload can be as detrimental to performance as high workload. One argument often heard in process plants regarding under-loaded console operators is that the low workload is necessary to ensure the operators have enough time to think and plan. But do they use the free time for job-related thought? This is the question that was addressed in aviation by Stephen Casner and Jonathan Schooler using 18 pilots in a 747 simulator (Casner, S. and Schooler, J., Thoughts in Flight: Automation Use and Pilotsí Task-Related and Task-Unrelated Thought, Human Factors: The Journal of the Human Factors and Ergonomics Society, May 2014, 56: 433-442).
The pilots were flying an approach into JFK with two levels of automation wherein they needed to pass two critical approach points at a given speed and altitude. Every two minutes the pilots were queried as to what they were thinking about:
Of the three, percentage time on higher level flight related thoughts did not vary, regardless of whether they were successful in making the crossing or the level of automation. The pilots had the highest percentage of thought on the task at hand if they had low level of automation or the plane was not at the desired altitude/speed at the crossing point. With automation and altitude/speed at target, thoughts shifted from the task-at-hand to things unrelated to flight.
In summary, we see again that having excessively low operator workload will not necessarily result in improved performance, particularly if the goal is to provide more time for thinking and planning. Do NOT expect that giving your operators more free time to think means that they will be thinking about the job.
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