I used to work with a guy just like our Bob's, but his name was Steve.
Steve had something happen to his brain along the way and had this huge scar on his head to prove he had surgery on it.
I was the crew lead, so I had to make lists of duties for my guys to do throughout the shift. When it came to Steve, I became perplexed right away. I could tell him to go do something and he would ok, but that was it. He couldn't see past that job and figure out what to do next. Then I tried giving him more, and in chronological order, to see what would happen. He did everything I told him, and again, that was it. I usually had to go looking for him and there he was, just waiting for something to do next after he finished the last duty on the list. It was then that I realized it was my fault for not adding the last most important command, "When done with all of this, come back to me for more". Once I got that part down, man oh man, what a worker! I swear, I could give him a list of like 20-30 things to do, taking breaks at the right times included, and he would do everything exactly right as I told him and then come find me at the end. If I screwed up by telling him to do something differently than how I actually intended, he would still do it but wrong because that's how I told him to do it. Just like a Bob, he only does what he's told and can't seem to think beyond the present, can't look to the near future and make informed decisions on his own.
Actually, I think Steve would make a better race car driver than Bob, so I shall start calling my next driver Steve. At least he'll do what I tell him!