My babe seems to be fairly consistently nodding for "yes" now (also sometimes saying "yeah," while nodding). Not sure I'm ready to call it (it's only been a few days), but so far it only corresponds to when she really means "yes" (particularly wrt EC-- "do you need to go potty?")
She isn't shaking "no," yet, but it occurred to me... aren't kids "supposed" to shake their heads "no" before they nod "yes?" Or did I make that one up? Rudimentary Googling led me nowhere. What has been your observation/experience?