This could only disprove or fail to disprove the absence of any noticeable effect on other drivers, since them behaving differently might make you behave differently, by, say, subconsciously inferring from their behavior that you are in the helmet-wearing group.
This could only disprove or fail to disprove the absence of any noticeable effect on other drivers, since them behaving differently might make you behave differently, by, say, subconsciously inferring from their behavior that you are in the helmet-wearing group.
Good point.