Even with proper nutrition and perfunctory care, if an infant does not receive affectionate social interaction, her physical development will be stunted and her brain development compromised. The important role of sensory stimulation for brain development—discussed in Part II—is thought to be an important mechanism in an infant’s development. Even moments after birth, the child needs an attachment figure, and the social behavior of the newborn is designed to induce the parent into providing the resources required for her growth.9 In other words, the infant is typically quite effective at convincing her caregivers to relinquish their personal resources of time and money. Of course, the infant’s needed resources include food and protection, but there are other important needs to be filled. The caregiver must also control the infant’s physiological functions, such as temperature regulation. Specifically, the caregiver regulates the child’s temperature by dressing her in an appropriate manner as well as through physical contact and heat exchange. In fact, the caregiver controls many of the infant’s physiological systems and this appears to be a major mechanism for the caregiver to program the infant. This is a critical concept, because it further indicates that sensory stimulation is important and further explains why there is an certain level of sensory stimulation required for optimal development.
Myron Hofer calls the mother’s sensory stimulation of the infant a “hidden regulator” of the infant’s physiology and behavior.10 For example, touch regulates the infant’s levels of growth hormone, and the caregiver’s presence reduces the infant’s levels of stress hormone during stressful events. The regulatory function of the caregiver occurs fairly naturally once an attachment is formed and the caregiver has had the opportunity or has taken the time to learn how to parent (parenting is not an innate skill). This provides stimulation of the appropriate sensory system at the appropriate intensity and patterning to promote healthy development. There is no special receptor for love, a feeling of safety, or any other emotion to enter the child’s brain. The only way information about attachment quality can be transduced to enter the brain is through our five senses. This pattern of sensory stimulation is how experience enters the brain and changes its development via changing chemicals and individual neural activity. Healthy attachment naturally provides the developing brain with the appropriate sensory stimulation and neural activity. As is suggested by the wide range of child rearing approaches in different cultures, a wide range of types and patterning of sensory stimuli can produce a healthy child that matures into a healthy adult