SOURCE: http://www.halcyon.com/jmashmun/npd/six.html

Narcissists have normal, even superior, intellectual development while remaining emotionally and morally immature. Dealing with them can give you the sense of trying to have a reasonable discussion with a very clever six-year-old — this is an age when normal children are grandiose and exhibitionistic, when they are very resistant to taking the blame for their own misbehavior, when they understand what the rules are (e.g., that lying, cheating, and stealing are prohibited) but are still trying to wriggle out of accepting those rules for themselves.