Sure, sure, to test your reflexes. Everybody knows that. Isn’t the delayed kick in the pants when the doctor turns his back a slapstick mainstay? Harpo invented it. Or was it Curly? Anyway, testing ...

You might have experienced the popular knee jerk in the doctors room or you may have heard of someone having an automatic 'knee-jerk response' to a situation without thinking. Strange, isn't it? Well, ...