An infant learns to recognize her parents within the first few months of birth by sight, sound, and even smell. Up until six months, a baby will usually seem interested in other adults as well, engaging in games such as peek-a-boo.
After six months, many babies undergo a period of fear and unhappiness around anyone except their parents. The child may burst into tears if an unknown person makes eye contact or shriek if left even momentarily in the care of an unfamiliar person.
This stranger anxiety is a normal part of a child’s cognitive development; the baby has learned to differentiate her caretakers from other people and exhibits her strong preference for familiar faces. Stranger anxiety begins around eight or nine months and generally lasts into the child’s second year.
Stranger anxiety can be upsetting to friends and relatives, who may feel rebuffed by a suddenly shy child. The baby may reject a babysitter she was previously comfortable with or grow hysterical when relatives visit. It can also be a trying time for the child’s parents; the baby may reject the parent who is not the principal caregiver.
Furthermore, the child may be particularly upset around people who look different to her—perhaps people with glasses, men with beards, or people of an unfamiliar skin tone. Parents should respect the child’s fear as much as possible, and allow her to approach people as she is able.
Extra time should be spent with the child when dropping her off at a babysitter or relative’s house. The new face should be introduced slowly. If the child does not want to be hugged by or sit with a relative, it is unwise to force her. Generally, the child will outgrow his fear and may become more sociable.