Advantage of MultiColor Taillights 3482On Wed, 4 Jan 2006, C. E. White Not by a long shot! They are legal in the US, Canada and Mexico. Required in almost every other country in the world, for 30 or more...
Daniel J. Stern
I disagree. As an engineer who designs test scenarios to validate not only the system under test but the TEST, this is exactly the sort of information that tells you whether or not the TEST is valid.
If that level complexity in events and conditions only tangentially related to the test exist and can affect the outcome, then the experiment is out of control and of questionable value in determining what the REAL cause-effect relationship is. To pick one example, you say that the driver may be conditioned by seeing the same type of vehicle before. That's pure speculation- the REAL reason for a different reaction time could be related to any number of other factors unique to that vehicle, not just the amber rear turn signals. Maybe it just looks a lot more painful to hit than some other vehicle. Maybe its design accentuates the brake lights. The experiment is uncontrolled without comparisons using the SAME vehicle (or the same simulated vehicle to avoid contamination from the driver's experiences with real vehicles in the real world) with nothing but the turn signal color changed.
FWIW, that's one reason why I *HATE* human-factors engineering and try to avoid it like the plague personally, and take it with a boulder of salt when someone gives me a bunch of human-factors test results. Its damn near impossible to come up with tests that can't be easily tainted in this way. Its more psychology than engineering.
