Sylvia's infant daughter is smiling, bouncing in her crib, and reaches her arms toward sylvia. sylvia smiles at her daughter and picks her up, bouncing her gently. the two share smiles and laughs for several minutes. this exchange is:

Interaction synchronous

Explanation:

Interaction synchronous is a phenomenon where an infant mirrors the action of another person or carer. For example their facial expression and body movement - the infant moving their body with the tune rhythm of their carer. It is the procedure of how a parent and an infant behavior finally synchronized so that they are direct in response to one another. It was defined by the Feldman that it is a microlevel social temporal interaction between a parent and a caregiver. It is also called a symbolic exchange between a parent and a child. Interaction synchronous plays a vital role in the development of a child in social interaction, to understand symbols and to use capacity for empathy.  

There are three phases of play that are given by Brazelton et. al.  

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answer; longitudinal;