Dynamic patterns of behaviors before joint attention.

<p>Dynamic patterns of three behaviors from the 5 second before the onset of coordinated attention, in either child-leading (left column) and parent-leading (right column) cases. <b>Top</b>: the proportion of time that either child or parent looked at each other's faces prior to joint attention. Only in the case of child leading, an increase of face look from parent to the child's face started around 2000 ms before the onset of joint attention. <b>Middle</b>: the proportion of time that either child or parent was holding the to-be-jointly-attended object prior to joint attention. In the case of child leading, both children and parents increasingly held the target object. In the case of parent leading, only the probability that the parent held the target object was dramatically increased before joint attention. <b>Bottom</b>: the proportion of time that they looked at each other's faces in both child-leading and parent-leading cases shows little change of mutual gaze.