Table 1.

Development of attachment in infancy and early childhood

Biobehavioral shifts and attachment benchmarks during periods between shifts	Behavioral characteristics
First 2 months	Infant has limited ability to discriminate among different caregivers; recognize mothers’ smell and   sound but no preference expressed.
2–3 month shift	Emergence of social interaction, with increased eye to eye contact, social smiling and responsive cooing.
2–7 months	Able to discriminate among different caregivers but no strong preferences expressed; comfortable with   many familiar and unfamiliar adults and intensely motivated to engage them.
7–9 month shift	Emergence of selective attachment as evidenced by onset of stranger wariness (initial reticence) and   separation protest (distress in anticipation of separation from attachment figures).
9–18 months	Hierarchy of attachment figures evident. Infant balances the need to explore and the need to seek   proximity; these become even more evident with independent ambulation emerging at approximately   12 months. Secure base behaviors (moving away from the caregiver to explore) and safe haven   behaviors (returning to the caregiver for comfort and support) both evident.
18–20 month shift	Emergence of symbolic representation, including pretend play and language.
20–36 months	Goal-corrected partnership in which the child becomes increasingly aware of conflicting goals with   others and for the need to negotiate, compromise and delay gratification.
36+ months	Secure base and safe haven behaviors continue but behavioral manifestations become less evident   because of the child’s increased verbal skills. Internal representations of attachment more accessible   to observers through narrative doll play.