schaffer & emerson's sequence of attachment:
up to 3 months; most babies respond to any carer
3-7 months; can distinguish difference between main carer & others. they accept care from others
7-9 months; infant looks to particular people for security, comfort, & protection. they show fear of strangers & unhappiness when separated from their main caregiver. some more likely to display fear of strangers/stranger anxiety than others
9 months +; baby starts to become more independent & forms several attachments, referred to as multiple attachments