The brain is shaped by early experience, specifically, the mothering (nurturing responsive care) we receive from mothers and fathers.
Fathers and mothers and other adults provide social experience for children throughout life. These experiences in early life establish how well the brain develops, not only for health and intelligence but sociality.* Autistic children (autism refers to social awkwardness, which seems to have a variety of causes) have difficulty imitating the vitality dynamics in others (the "how" of interpersonal signaling), though they can imitate means and goals accurately (the "what").
“"We naturally experience people in terms of their vitality. We intuitively evaluate their emotions, states of mind, what they are thinking and what they really mean, their authenticity, what they are likely to do next, as well as their health and illness on the basis of the vitality expressed in their almost constant movements"
Five dynamic events are linked together in our experience of vitality: "movement, time, force, space, and intention/directionality….Vitality is a gestalt, a whole that emerges from these components.
"It is not analyzed in any conscious way piece by piece, any more than a familiar face is, even though each separate element could be taken aside and studied in isolation."
Colwyn Trevarthen (1999) coined the term, communicative musicality, to describe the interpersonal dynamics of synchronizing motives, intentional states and behaviors with another—the forming of a duet of "being with" the other person by sharing the dynamic flow.
The early social life of the baby shapes capacities for vitality dynamic movement. From 2.5 to about 6 months of age, the baby's behavior is highly responsive to his parent's behavior through facial expressions and vocalizations. Interactions become rich and mutual. "Face-to-face play becomes the main "game." The eyes, face vocalizations, gestures, and body tonus take center stage."
Subsequently, as the baby is able to control movements more, they more easily mirror their social partner. Dads are particularly good at playing with their children and through such play the child is learning scripts for social relationships.
"Dynamic forms of vitality are part of episodic memories and give life to the narratives we create about our lives. Accordingly, dynamic forms of vitality provide another path for psychotherapy to access non-conscious past experience" which includes "implicit relational knowing (how we implicitly know how 'to be with' a specific other"
Dads, like moms, help children learn ways to "be with" others. Each relationship is a way to learn an alternative pattern: "Dad and I relate this way; Mom and I relate that way". Learning reliable alternative patterns prepares the child for a varied social life.
Babies are optimally aroused to play and be happy in a particular zone of arousal. Too little or too much parental stimulation shifts the baby out of the optimal zone. It takes practice for adults to learn the optimal zone if they have not had much prior experience "conversing" with babies.
Self control of arousal (through the later-developing cortex) is not in place till after most of the first year, so keeping baby from over or under arousal is largely up to the parent. Of course, the baby can do simple things like turn away or close eyes but the baby has limited capacities for self-calming. If these are unsuccessful the baby cannot self-calm.
Dads can help baby stay calm with skin-to-skin carrying (a remarkable calming tool), rocking and patting, and other touch-plus-movement behaviors. Face-to-face play between baby and parent becomes a clinical window on how the parent-child partnership is going: "It reveals when parenting is easy or hard, natural or forced, intrusive, controlling, disorganized, passive, aggressive, rejecting, etc." Therapists who attend to these relational signals can use them to guide their treatment of the dyad.
This knowledge is implicit relational knowing, nonconscious and nonverbal and is predominately processed in the right hemisphere, which rapidly develops in the first years of life. Parent "matching/mismatch of vitality forms can shape what the infant does and how he feels about doing it. It is like sculpting his mind from the inside out."
Two things happen: Babies experience toxic stress from the distress that arises when they don't get what they need. For example, lack of comforting companionship care: they are left alone or left to cry
Second, babies don't receive the appropriate stimulation to grow what is scheduled to grow at that time. Yes, human brains are plastic, but not that plastic: children can be left with gaps in various systems undergirding intelligence, physical health, mental health, social and moral capacities, which may not show up immediately but after further maturation that is dependent on those earlier foundations that are missing. These gaps are difficult if not impossible to repair later.
Daniel Stern asks why nature planned for babies not to speak or understand words for the first year or so of life. His answer is that they "have too much to learn about the basic processes and structures of interpersonal exchange. In particular, they have to learn the forms of dynamic flow that carry social behavior. In addition, they have to learn this before language arrives to mess it all up. The basic structures are all non-verbal, analogic, dynamic Gestalts that are not compatible with the discontinuous, digital, categorical nature of words."
An illustration of the types of capacities early life experience develops, when the brain's right-hemisphere develops more rapidly,** is provided by Jill Bolke Taylor, neuroscientist. She described the sudden and unexpected right-hemisphere dominance she experienced after having a stroke in her left cerebral hemisphere: "Our right hemisphere is designed to remember things as they relate to one another. Borders between specific entities are softened, and complex mental collages can be recalled in their entirety as combinations of images, kinesthetic, and physiology. To the right mind, no time exists other than the present moment, and each moment is vibrant with sensation. … the moment of now is timeless and abundant …The present moment is a time when everything and everyone are connected together as one. As a result, our right mind perceives each of us as equal members of the human family. It identifies our similarities and recognizes our relationship with this marvelous planet, which sustains our life. It perceives the big picture, how everything is related, and how we all join together to make up the whole. Our ability to be empathic, to walk in the shoes of another and feel their feelings, is a product of our right frontal cortex."
Human beings are complex creatures whose capacities are developed mostly after birth, unlike virtually every other animal. We need dads and grandfathers, along with moms and grandmothers and others, to provide the nurturing care, the mothering, that babies need to grow well.
Note that womb experience also influences brain development and we can inherit some traits due to the experiences our grandparents had, like anxiety.
** The right hemisphere tends to process, filter and act on the world nonverbally, whereas the left hemisphere tends to house the areas of the brain related to verbal processing and expression.