November 6, 2007 | Barb Carr

“Is this a bomb or a bottle of shampoo?”


Human Factors Series 1: Taking Signal Detection Theory (SDT) out of the Laboratory and into the Workplace

Everyday we have to make decisions about uncertain events. Signal Detection Theory is a model of how people make uncertain decisions. To put it simply, can you single out one object (beep, light, defect…) from the surrounding workspace? How important is it not to miss the object you are searching for (correct hit) and how detrimental to you is it if you indicate the object is there when it isn’t (false alarm)? What does senior leadership reward?

An article published in stated that 75% of the fake bombs and explosives sent through LAX Airport security screeners during an undercover terrorism drill passed through undetected.

Airport authorities were not surprised. The simulated devices were not “sticks of dynamite” but “more like caps on a pen….a piece of metal with a wire in it. TSA’s remedy is to send poorly performing screeners into remedial training until their screening scores get better or remove the employee. To see Signal Detection Theory used to assist training for security screens see this SDT Simulation.

A former security director at LAX cited in the article stated that authorities could: purchase more advanced screening equipment, fund the proper number of screeners at each airport and ensure that screeners who consistently fail covert tests are removed.

The question I ask is how does one get from the incident of missing the explosives in the screening process to corrective actions such as remedial training, possible firing, hiring more employees, and purchasing better equipment? This is where the human factors science such as Signal Detection Theory behind TapRooT® could have helped with the root cause analysis.

Use a structured root cause analysis like TapRooT® that asks questions tied to human engineering such as were errors (targets) detectable? Are choices made by the person subject to knowledge-based decisions? Are the safeguards or barriers dependent on human action?

While types of human error are subject to change, human factors science continues to be introduced into the workplace with increasing usability. Replacing “common sense” with a structured root cause analysis based on science will continue to improve corrective actions.

Human Factors Series 2 will discuss Management Systems influence on correct hits and false alarms.

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