You two make some very good points [@Mistiel][@Lalliman]. What I was proposing though, could be very difficult for some people to understand. Especially those who have never suffered mental illness. 

The stunted ability to learn wouldn't stem from a deficiency in logical thinking. Rather, it would arise from the difficulty of emotional expression in this world. Think of the phrase "I do not have a mouth but I must scream". This deficiency wouldn't hinder people from learning everything. People could still learn logical tasks just fine. The ability to learn to express more complex and layered ideas such as love, regret, indifference, etc. That integral part of the human experience would be difficult for these people to grasp completely.

Playing in an RP where people have trouble expressing themselves completely can be done. Only using a couple of words to try to confer deeper emotions and intentions. It would, I dare say, make for a rather interesting experience. Here's an example:

[i] Never had he felt that way before. A flood of sensations both familiar and alien. Difficult to understand yet easy to recognise. Nobody else but her. Like a spell, a drug, concocted by the beautiful yet terrifying. There was so much he wanted to say, though it seemed, there were not enough words in the world to say it. 

And how could he describe it? Like a pleasant yet painful vice-like grip on his heart? Like drowning from the inside out? Like a feeling of unbridled ecstasy? No description he could fathom could ever come close to describing the sensations he experienced. To try to describe such a thing would surely invite an early death. The sensations only meant for her. Truly, for such a thing, only one word came to mind.

"Lily" he said. [/i]