I haven’t cared for too many horses over my years, but about ten years ago when carrying buckets of feed to my two horses, I noticed the following which brought me to an important understanding of Pavlov’s research. Guinness and Maggie would at first be milling excitedly in their paddock when they saw me emerging from the shed where the feed was kept, but as I neared the gate they both then got down to some serious hoof stomping and head-bobbing only to desist when their snouts were deep into their respective feed buckets. And when you think about it, this kind of stomping/bobbing behavior is the basis for a lot of horse tricks as in “Mr. Ed,” and especially “Clever Hans” who had the psychology community hoodwinked for a while in the early twentieth century when he would stop stomping as he had arrived at the proper answer to an addition problem posed by a researcher. So my question is, why do horses stomp the ground and also bob their heads up and down when they are excited?