It's completely possible that: - it only affects some units - some people are exhibiting superstitious behavior (http://en.wikipedia.org/wiki/B._F._Skinner#Su

It's completely possible that: - it only affects some units - some people are exhibiting superstitious behavior (http://en.wikipedia.org/wiki/B._F._Skinner#Superstition_in_the_pigeon http://en.wikipedia.org/wiki/B._F._Skinner#Superstition_in_t...) - some combination of the two