Object relations theory
Fairbairn's model

The model is completely interpersonal in that there are no biological drives of inherited instincts. When the maternal object provides a sense of safety and warmth, the child's innate "central ego" is able to take in new experiences, which allows the child to expand their contact with the environment beyond the tight orbit of their mother. This is the beginning of the process of differentiation, or separation from the parent, which eventuates into a new and unique individual. As long as the maternal object continues to provide emotional warmth, support, and a sense of safety, the child will continue to develop throughout childhood. However, if the parent fails to consistently provide these factors, the child's emotional and psychological development stops and the child regresses and remains undifferentiated from their mother. The following quote illustrates the basis of Fairbairn's model:
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