Humans are wired for connection.  We develop emotional resilience and stress tolerance from our earliest experiences with our primary caregivers.  These caregivers also help orient us to the world.  Research now indicates that we carry our earliest attachment patterns from infancy into adulthood for better or for worse.

In 1975, Dr. Edward Tronick ran what he called The Still Face Experiment with infants and their primary caregivers to show how sensitive babies are to caregiver responsiveness and mood. Dr. Tronick is the Director of UMass Boston's Infant-Parent Mental Health Program.

In a demonstration of his experiment, below, a mother first spends 3 minutes responding to, and interacting with, her baby and 3 minutes physically present but non-responsive to the infant.  The interaction we see in the video clip is consistent with Tronick's findings throughout his study.  The infant becomes very distressed during the latter portion of the experiment even though she is not being actively physically or emotionally mistreated.  The results are a very powerful testament to the power of the human need to be "seen" and an example of how sensitive infants are to their surroundings even at a very young age. Among other things, Tronick applied his findings to situations in which an infant is being raised by a depressed parent.

https://www.youtube.com/watch?v=apzXGEbZht0