Chicken Recall...The Good Kind!

I was at a barn sale today, and I heard an older gentleman telling someone else how he can always get his free range chickens to come to him. He said he goes outside with some treat in his closed fist...cracked corn, birdseed, whatever. He crouches down and holds out his closed fist toward his chickens. When they show interest, he slowly opens his hand and lets them eat from his hand. He has done this for a while, and now the chickens will come to him whenever they see him making a fist. I was thinking this could come in handy at times if you need to catch your chickens!