ABSTRACT
Just as the left hemisphere of the brain communicates to others through conscious linguistic behaviours, so the right hemisphere communicates its less conscious states to other right hemispheres that are ready and able to receive these messages. In effect, what we see happening between primary caregiver and infant is a process whereby the mother lends her right hemisphere in the service of the developing brain of the infant, and equally the infant's developing capacity to manage an array of affects. In the course of these communications the infant's autonomic nervous system is also activated, facilitating control of the level of physiological arousal and its impact on affective states. Siegel (1999) puts forward the idea that each of us has a `window of tolerance' in which various intensities of arousal can be processed without causing undue discomfort or distress. This window of tolerance is based on levels of arousal of the sympathetic and parasympathetic branches of the nervous system. The sympathetic branch controls heart rate, alertness, respiration and sweating, while the parasympathetic branch performs a de-arousing and inhibitory function. Ogden et al. (2006) also draw on this idea, highlighting the physiological and affective implications for an individual of moving too far beyond either boundaries of their window of tolerance. At the upper end we have the potential for hyperarousal, leading either to hypervigilance, with panic, rage or terror, or to high arousal coupled with immobility (the `freeze' response). At the lower end we have the potential for hypo-arousal with the numbing of emotions, or the experience of shame, despair, or humiliation. In a relatively benign environment the infant is able to develop a sense of a maturing self through experiences at the edge of its window of tolerance that do not lead to extreme traumatic affective experiences of the kinds outlined above. Environments that are less benign pose serious challenges to the infant
out: `the interactions that occur have direct effects on the emotional experience in that moment. Within the context of an attachment relationship, the child's developing mind and the structure of the child's brain will be shaped in such a way that the ability to regulate emotion in the future is affected (p. 285, italics in original).
