Though not a directly applicable analogy, it reminds me of the little survey George Hickox did with an E-collar, in the seminar I took, to show how little electric stimulation was being used on my dog and the others by him when demonstrating proper E-collar use for training. He passed the collar around and had each of us hold it while he started energizing the collar from the lowest setting up to the point where each person could feel it. I could feel a #1 setting, my wife a #3, others couldn't feel anything until much higher settings up to #12. My dog was responding to stimulation #1 on her neck, other dogs no higher than #3 was needed to get a response. Correction settings were around #10 for the dogs. This collar system went up to #50. He sold a lot of those collars that day. this just illustrates the differences between individuals.