One of the most important factors that affect child development is the relationship of the child with their primary caregiver. This common sense statement is a tenet of developmental psychology known as attachment theory. John Bowlby, the creator of this theory, wanted to examine how early childhood experiences influence personality development. Attachment theory specifically examines infant’s reactions to being separated from their primary caregiver. Bowlby hypothesized that the differences in how children react to these situations demonstrates basic behavioral differences in infancy that will have consequences for later social and emotional development.