Open question

I have a question for you guys out there. Feel free to post a comment or email me. I have observed -and I sort of remember from personal experience- that when children are playing with multiple dolls, they need to be holding the one that is virtually "speaking" at a time. In other words, in make-believe conversations, the dolls that are doing the talking need to be held in the player's hand. Otherwise, dolls that are not being held do not "speak". Of course there may be exceptions, but I wonder if this particular behavior is normal accross cultures. Thanks!