I don't think chickens actually "imprint" on you very easily. I have one that I call "buddy" because she always comes when called, or when she thinks I have food. But if I ever come outside without food, the rooster's hunt for food has her attention more.
She's tame though - I can pick her up, pet her, scratch her, carry her around and she doesn't squirm one bit. And if I lift logs and anything that might have bugs under it, she's more than willing to "follow" me. But again - it's only for food, or the idea of getting food.
Then I got my latest chick, "Chippy". Chippy is different. First, he's a bantam, which are great at flying. Second, he hatched alone and was not/could not be raised with any other chicks I had. He was too young for the older ones (got picked on) and too old for the younger ones (picked on them). So he has been alone for his entire life now - about a month. I have taken him outside to socialize with the other chicks, but he won't have it. He sticks with me.
What really got me on "imprinting" though, was when he gets scared, lonely, or gets picked on, he looks for me and follows my shoes. When we are outside, he does NOT get any treats from me. He gets all of his food himself, by pecking at the ground for bugs and plants. I don't do like I did with my others and flip things over that might house bugs underneath. He simply goes outside and gets placed on the ground. But I am his guardian, and he KNOWS it. Any sign of trouble what so ever will bring him flying to my feet. And if I'm sitting on the garden wagon, he will fly up to sit with me, then sit on my leg and preen himself.
There IS a difference between imprinting, and being tame. But there is also a difference between "training" an animal to do something (i.e. respond to treats or food), and the animal actually trusting you. Chippy has definitely imprinted on me, because he runs to me when he thinks he is in danger. THAT is absolute trust.
He also doesn't make the loud, annoying "lonely-chick" cry when I'm near him. But he will do that if I step away and he notices.