Well even without having done such a study, I can assure you that your brain reacts pretty heavy on zaps. The reason for that is the same as it is for gambling addicts: it’s called variable reward. A variable reward is an reward that you know you will get at some point, but you have no idea on when and how big the award (zap) will be. The anticipation of a reward is proven to be really addictive, which is kind of the case with zapping.