Be assured. Your child is listening to you. I know how it doesn’t seem so, much of the time, but look at the examples of how your child is listening to you (and watching you) – by the way he imitates you. At least as a toddler, he is not capable of turning that on/off. Cherish the times he shows you the behaviors you want to see, and have patience to weather the storms of the testing/(“defiant”) behaviors.