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Reverse Highlighting?


What if your process graphics did not show any process variables unless they were “abnormal” is some way? While this sounds “insane,” I have heard that such a system was attempted years ago at the infancy of the distributed control revolution in process control. Now the Air Force is investigating a display technique that utilizes some of those same principles, but in a different manner. The goal in both is to enhance detection of signals through reduction in visual noise.

In “Heuristic Automation for Decluttering Tactical Displays” (St. John, M., Smallman, H., Manes, D., Feher, B., and Morrison, J., Human Factors , Vol 47, No. 3, Fall 2005, pp509525), the authors investigated removing or de-emphasizing “low threat” aircraft from an air defense tactical display.

Three conditions were evaluated:

(1) all aircraft were shown the same,

(2) low threat aircraft were dimmed (65% transparent), or

(3) low threat aircraft were invisible.

In essence, rather than highlighting the important, they de-highlighted the unimportant. Both of the latter conditions produced better performance in time to respond, with the “invisible low threat” condition generating a 25% improvement in threat detection. Users preferred the decluttered displays, due to their “allowing me to get in front of my rules of engagement rather than behind.” However, changes in threat level were hard to detect, and the authors caution that the monitoring was for short, rather than longer, more real-life periods of time (precluding the creation of automation bias effects).

Consider such a system for process graphics. In steady state operation, those variables not related to unit optimization would fade, leaving such parameters as those associated with advanced, multivariable control and/or product analyzers. In an upset, optimization variables would fade, while those related to safe operating limits would increase in intensity. As the authors of the paper noted, perhaps the hardest part of such a system is to devise the algorithm by which “threat level” is quantified and used to alter the display variables.

Perhaps an apology is in order to the individual who proposed the “insane” idea of showing only those variables that were abnormal.

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