Instinctive Drift was something I found really interesting while reading the textbook. Marian and Keller Breland were students of B.F. Skinner's and they wanted to take operant conditioning to the next level, by training animals to do an array of skills. Though they were successful most of the time, there were instances where the animals they had been training to behave a certain way would wind up doing whatever they felt like doing, and started to perform in a more classical conditioning way than an operant way. Thus making instinctive drift, "an instance of classical conditioning in which a fixed action pattern gradually emerges and displaces the behavior that is being operantly conditioned." Maybe this is where the saying "can't teach an old dog new tricks" came from! LOL