"I was just...."

Lately, whenever we ask Collin to do something, we have to repeat our request a few times before we even get an acknowledgement from him or even a response.  When he does respond, it's usually, "I was just finishing this" or "I was just going to do it"....and then he still does not do what we asked him to do.  We know his ears work....but he is just not interested in listening and doing anything we ask him to do. Oh yeah, that's right....he's 4!