DD is rather literal. We've worked on it by intentionally upping our use of idiom and asking her if she knows what they mean. I've noticed that her understanding of humor and nonliteral language has improved a lot since she started reading a lot of Peanuts, Calvin and Hobbes, Garfield, etc. She also got funnier! That's an easy prescription--comics.
It's not something my DD8 seems to have an issue with, but she's being raised in a family where spoken language is regarded as a plaything. It's common to hear nonsense rhymes, made-up songs, and invented slang in our household.
This is absolutely true here, too, but DD still has the tendency. I think it's just the way her mind is. She's also extremely exact and remembers details that I never would. It can be very useful, I must admit.
Interestingly, she is extremely good at analogies. It was her highest subtest score on her IQ test and she can knock them out of the park generally.
