The sharing of affective states is the most pervasive and clinically germaine feature of intersubjective relatedness. This is especially true when the infant first enters this domain. Interaffectivity is mainly what is meant when clinicians speak of parental “mirroring” and “empathic responsiveness.” Despite the importance of these events, it is not at all clear how they work. What are the acts and processes that let other people know that you are feeling something very like what they are feeling? How can you get “inside of” other people's subjective experience and then let them know that you have arrived there, without using words? After all, the infants we are talking about are only between nine and fifteen months old.

Imitation immediately comes to mind as a possible way one might show this. The mother might imitate the infant's facial expressions and gestures, and the baby would see her doing this. The problem with this solution is that the infant could only tell from the mother's