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.
John Bowlby
According to attachment theory, attachment in infants is primarily a process of "proximity seeking" to an identified "attachment figure" in situations of perceived distress or alarm for the purpose of survival. Infants become attached to adults who are sensitive and responsive in social interactions with the infant, and who remain as consistent caregivers for some months during the period from about 6 months to two years of age. Parental responses lead to the development of patterns of attachment which in turn lead to "internal working models" which will guide the individual's feelings, thoughts, and expectations in later relationships. More specifically, Bowlby explained in his three volume series on attachment (1973, 1980, & 1982) that all humans develop an internal working model of the self and an internal working model of others. The self-model and other-model are built off of early experiences with their primary caregiver and shape an individual's expectation on future interactions with others and interactions within interpersonal relationships. The self-model will determine how the individual sees themselves, which will impact their self-confidence, self-esteem, and dependency. The other-model will determine how an individual sees others, which will impact their avoidance or approach orientation, loneliness, isolation, and social interactions. In Bowlby's approach, the human infant is considered to have a need for a secure relationship with adult caregivers, without which normal social and emotional development will not occur.