Some implications of the onset of ambivalence in the second six months of life have been related to characteristics of depression in adulthood. A salient development at the onset of ambivalence is seen as the radical restructuring of the self-boundary. Initially all benign experience is within the self-boundary, and all negative experience outside it and ego-alien. At the point of successful resolution both positive and negative self representations must be within the self-boundary but that boundary now excludes both positive and negative representations of other persons and of the non-human environment. Depressive symptoms are related to the inappropriate continuation of the primitive good-bad boundary; inadequate establishment

of self-other boundaries; faulty development of the sense of self, of the ego-alien and of separate-but-related; unstable internal structuring of self and of others and the world; and an experienced helpless dependence on another for one's functioning.