I think they'd basically come out animals. If we went all the way up til the mid-20s, they'd have little chance of learning anything aside from the most basic of language skills. Maybe a bit brighter than an ape that knows sign language, or an especially intelligent parrot. It's brain will have gone through it's formative years without being stimulated and needing to grow. If the room were sterile enough in appearance (like, say, all white with no evidence of a pattern), any independent thought it might have should be completely abstract, since it has nothing to base imagination or thought on. He'd have to be fed of course, and given some sort of bathroom, so I guess there'd be some influence on his thoughts from those. Probably driven insane by sexual urges that he can't even identify without knowing what a female even is. This is making me so hard.
