( ( Major Update ) )
At a fundamental level, automatic toilet flushers generally use infrared light as their cue to determine whether or not there is someone currently sitting in front of them. They don't just see ambient infrared light, however; instead, they shine an infrared LED at you to ensure that there is always plenty of "illumination" for their sensor to work with.
As it turns out, then, this means that there are two factors to worry about...
- Reflectivity of "target"
This was my first observation: when I wore clothing that absorbed more light, then the sensor had more difficulty tracking me. Deeply textured, dark fabrics are the most likely to cause an issue; smooth, light-colored fabrics are consistently fine.
- Distance to sensor
Moving closer to the sensor is just like moving a flashlight closer to a wall; the reflected light looks brighter and brighter, because it's concentrated into a smaller and smaller area. This continues right up until the flashlight is touching the wall, at which point you can no longer see any reflected light because the flashlight itself blocks your view! It actually turns out that the same principle applies to automatic toilet flushers, because an object touching the sensor is invisible to the sensor.
My favorite vest was black, fuzzy, and loose fitting. This meant that the sensor already had difficulty tracking me, but it could make do as long as I didn't violate the distance rule.
- Whenever I leaned forward too far, the reflected light wouldn't be bright enough; the sensor thought I had stepped away, and so the toilet would flush.
- Whenever I leaned back, the vest would swing back even further; whenever the vest touched the sensor, it thought I had disappeared completely, and so the toilet would flush yet again.
I tested three solutions, which were all equally effective:
- Ensure that my outermost layer of clothing was not black & fuzzy;
- Ensure that I never allowed any part of my clothing to touch the sensor;
- And finally, Subjectivist's solution with the toilet paper also did the job equally well.
Theoretically, one could also solve the problem by always sitting bolt upright and being very careful not to move... but somehow, that option never appealed to me. (lol)