Developmental psychology
Attachment theory, originally developed by John Bowlby, focuses on the importance of open, intimate, emotionally meaningful relationships. Attachment is described as a biological system or powerful survival impulse that evolved to ensure the survival of the infant. A child who is threatened or stressed will move toward caregivers who create a sense of physical, emotional and psychological safety for the individual. Attachment feeds on body contact and familiarity. Later Mary Ainsworth developed the Strange Situation protocol and the concept of the secure base.
Marinus van IJzendoorn
Van IJzendoorn's main research topic is attachment across the life-span. Attachment has been briefly defined as children's "strong disposition to seek proximity to and contact with a specific figure and to do so in certain situations, notably when they are frightened, tired or ill". Inspired by Darwinian evolutionary theory and Harlow's experimental work with rhesus monkeys, John Bowlby was the first to propose that human genetic selection had favoured attachment behaviours since they increased infant-parent proximity, which in turn enhanced the chances for infant survival. Attachment is considered to be an inborn capacity of every exemplar of the human species. Individual differences in the quality of attachment emerge in the first years of life, and central to attachment theory is the idea that parenting, more specifically parental sensitive responsiveness to the infant's distress signals, determines whether children develop a secure or an insecure attachment relationship with their primary caregiver. Van IJzendoorn introduced in 1995 the quantitative model of the ‘transmission gap’ between parents’ attachments and their infants’ attachment as mediated by parental sensitive responsiveness. This model generated a host of empirical studies trying to bridge the gap (see for a meta-analysis of this work).