Of course, positive experiences are not the only experiences that have impact on an infant’s or toddler’s brain development. When adults ignore babies’ cries or respond to crying with abuse, the infants or toddlers are not having the kinds of experiences they need to build the typical rich and complex neuronal network of the well-developed brain. Infants who repeatedly experience frightening events such as physical or sexual abuse will constantly utilize the parts of their brain that focus on survival and responding to threats. In a similar way, infants who experience the chronic stress of neglect, hunger, cold, fear, or pain will also utilize their brain’s resources for survival. This is the “stress-response” system at work.

According to Perry’s research (1996), chronic stress in the first years can cause changes in attention abilities, impulse control, sleep, and fine motor control. Chronic activation of the parts of the brain involved in responding to fear can “wear out” other parts of the brain involved in higher level thinking. As an evolutionary function of the brain, when survival is at stake people do not use their more thoughtful, reflective parts of the brain. Instead, cortisol, adrenalin, and other hormones activate the part of the brain that focuses on choosing a survival strategy: fight or flight, or in very young infants, freeze. As these neural connections are reinforced through usage, they become the predominate pathways the brain uses to assess situations. Every event is perceived as a life-or-death situation. The brain that results from these early experiences may be highly adaptive in abusive or neglectful situations, but it is inadequate for the work of healthy relationships. The child who does not experience love, support, and positive social opportunities may not develop the memories— and therefore the neural pathways—needed to recognize and understand them when they do occur. “The result may be a child who has great difficulty functioning when presented with the world of kindness, nurturing, and stimulation. It is an unfamiliar world to him; his brain has not developed the pathways and memories to adapt to this new world” (NCCANI, 2001).

Children who experience chronic stress in infancy use their brains differently later in life. They may be in a state of hyperarousal, always scanning the environment for signs of danger. These children may even evoke in others the abusive behavior that they fear, just to have some control over it. Therefore, a boy whose mother was raging and frightening may pick fights with other children, or a girl who was sexually abused may act seductively with a teacher. The opposite reaction to early frightening experiences is to feel so powerless that the child just freezes, or dissociates. Dissociation appears to be surrender to the situation, but the child feels as though she is not even present in the moment. During dissociation, the child may not even hear what is said to her, and so she does not attempt to respond. The child may have no memory of the experience. If children do not experience reliable responsiveness in their caregivers, they may later lack the neuronal pathways that would present adult assistance as a possible solution to problems. If children experience extreme deprivation in infancy, little contact with caregivers and little stimulation from the environment, they will develop significantly smaller than normal brains (Perry, 1996; Perry & Pollard, 1997). The brain may incorporate the effects of chronic frightening or neglectful early experiences for a lifetime.