Answer:
Reciprocal or synchronous
Explanation:
Emotions are a very important part of our consciousness. Emotions changes every times. These are depend on the situation and environment. If a person feels happy the emotions reflect happiness but if a person is not happy, emotions reflect sad emotions. Emotions depend of reciprocity.
As you reply to others on behalf of emotion, in return you will get a response. Thus here when parents change their emotions towards infants, the infants also change their emotions towards their parents. This is mutually regulated by responses that are called reciprocity or synchronization.