Abby's (defiant) language skills

Language is a way to gauge progression amongst kids, but I think it should also be noted when a child is smug in the face of language prompting.

Case in point:

• When I ask Abby to say, "Mama," she gets a wide smile on her face and pauses before she starts with, "dada ... dada ... DADADA."
   
• Abby's first word was "Bert." The child will not say "Ernie." She knows which one is Ernie. In fact, Ernie is her preference. She will say "Bert" until the cows come home. Instead of "Ernie" she laughs like Ernie. "Hee ... hee ... hee ... hee ..."
   
• I have repeated certain words for Abby over and over again hoping she'd pick them up. She hasn't. I think I've said, "uh oh" approximately 1,000,000 times since her birth. Has the child EVER said "uh oh"? Of course not. She hasn't even said anything that resembles "uh oh."
  
  But somehow, she has managed to figure out on her own how to say "cat." I say it's on her own because I have been trying to get her to say "kitty." That's all I use. But she says "cat."