A new paper from the School of Continuous Improvement independently manipulates a hand dryer's boost-relay wiring and indicator light, finding how long hands linger under the airflow tracks the light rather than measured drying power.
A ten-week manipulation of a campus hand dryer's boost relay and indicator light finds hands linger to the light, not the airflow
Nobody times how long they hold their hands under a bathroom hand dryer. A new paper from the School of Continuous Improvement did the timing for them, and traces what that duration is actually responding to.
Researchers spent a full term toggling two things on two shared campus hand dryers, on a rota nobody using the bathrooms knew about: whether the “boost” relay triggered by a double-wave gesture was actually wired to the motor’s high-speed winding, and whether the small indicator light above the sensor flashed when a wave was detected. Each unit’s own energy-monitoring anemometer and presence sensor did the rest, logging peak airflow and how long a visitor’s hands stayed under it across 3,142 visits.
The airflow never changed. The only thing that reliably moved was how long people were willing to stand there — and that moved with the light, not the motor.
— Dr Osei Vandermeer, Research Fellow and Convenor, Review Cadence Observatory, School of Continuous Improvement
Measured airflow held flat whether the boost relay was wired or physically isolated, and flat again no matter how many extra waves a visitor gave the sensor. Dwell time told a different story: hands left the airflow around four seconds sooner, on average, whenever the indicator light was active, regardless of whether the relay behind it was connected to anything.
Associate Professor Casimir Beng, whose Adaptive Metrics Lab supplied the anemometer logs, said the finding belongs on a growing list of campus sensors the Lab now treats as measuring the feedback rather than the fact, adding that the same rota-based test could run on almost any indicator light on campus.
For the School, the finding joins a growing file on what a sensor actually captures once it sits beside a control nobody has separately tested.
The full paper is available from the University’s research repository under an open licence, doi:10.5555/slop.3mnp9h.