Chickens are really good at telling the difference between two similar objects. You'll be able to tell when you watch this video of a chicken pecking only the hexagon she was trained to touch.
Lots of dog trainers go to "Chicken Camp" because learning how to clicker train a chicken can teach us a lot about how to train a dog. I tried chicken training last year, and it was a lot harder than I thought it would be. Here's what someone taught their chicken to do for camp graduation (the trainer is the woman standing at the back side of the table):