Does using sign language really accelerate a child's ability to speak?
I am considering teaching my 8-month-old sign language, and I can't sneeze without finding resources extolling the virtues of sign language for babies (most of which use subjective arguments, like easing you baby's frustration). However, I worry that signs could end up as a "crutch", and might hinder my daughter's verbal speech, and maybe even hinder her communication in general (verbal or nonverbal).
Are there any actual studies showing that teaching babies sign language is helpful? Even a study that concludes it doesn't hurt would make me feel better.