Attachment theory
Secure attachment is classified by children who show some distress when their caregiver leaves but are able to compose themselves quickly when the caregiver returns. Children with secure attachment feel protected by their caregivers, and they know that they can depend on them to return. John Bowlby and Mary Ainsworth developed a theory known as attachment theory after inadvertently studying children who were patients in a hospital at which they were working. Attachment theory explains how the parent-child relationship emerges and provides influence on subsequent behaviors and relationships. Stemming from this theory, there are four main types of attachment: secure attachment, ambivalent attachment, avoidant attachment and disorganized attachment.