My son has the ability to "hyper-focus" which he inherited from me. Normally it might seem that he is not paying any attention, because he is always fidgeting with something, but the amount of information he takes in is astounding. When he hyper-focuses, however, he does not register any external anything. You can talk to him and he may seem like he is responding, but the response is automated (I still do this) and all his attention is on whatever he is busy with.