Psychoanalytic theory defines attachment in terms of the satisfaction of oral needs, while learning theorists add the aspect of reinforcement.

Harry Harlow's research with monkeys and their need for contact comfort played an important role in the early development of attachment theory.

John Bowlby's idea of critical periods explains the biological predisposition humans have that increases the likelihood of forming attachments. An infant is programmed to cry and smile, while adults are programmed to respond to the infant. During the first few months of the child's life, such attachments are indiscriminant. After six or seven months, the attachments become increasingly directed to caregivers. Signs of attachment include a selective social smile beginning at six months and the emergence of stranger anxiety and separation anxiety.


1. Stranger anxiety - very anxious and fearful of strangers at six months. Typically disappears by age two.
2. Separation anxiety - severe distress when separated from primary caregiver beginning at six to eight months. Peaks in intensity at 14-18 months, continues until about age two, then diminishes.

Patterns of Attachment:

1. Secure attachment - a securely attached infant is mildly upset by the mother's absence and actively seeks contact with her when she returns. Mothers of securely attached children are emotionally sensitive and responsive.
2. Insecure (anxious/ambivalent) attachment - the infant becomes very disturbed when left alone with a stranger but is ambivalent to mother's return and may resist her attempts at physical contact. Mothers of these children are often moody and inconsistent in their caretaking.
3. Insecure (anxious/avoidant) attachment - the child shows little distress when the mother leaves and ignores her when she returns. Mothers of these children are impatient and unresponsive or provide their children with too much stimulation.
4. Disorganized/disoriented attachment - fear of their caretakers, confused facial expressions and a variety of other disorganized attachment behaviors mark these children. Eighty percent of infants who have been mistreated by their caregivers exhibit this pattern.