At what milestone do children typically begin to show stranger anxiety?

Children typically begin to show stranger anxiety around 6 months of age. This developmental milestone is associated with the emergence of a strong attachment to primary caregivers and the recognition of familiar versus unfamiliar people. At this age, infants become more aware of their surroundings and start to differentiate between those they know and those they do not.

Stranger anxiety reflects a child's growing social awareness and fear of unfamiliar individuals as a protective mechanism, serving to enhance the child's safety. As their cognitive abilities develop, they start to understand that people might not have the same intentions as their caregivers, leading them to exhibit anxiety or distress when approached by strangers.

Around 3 months, infants are generally more focused on interaction and may show smiles or laughter at familiar faces but aren't yet capable of displaying significant anxiety toward strangers. By 12 months, children often exhibit heightened attachment behaviors and may also show separation anxiety, but the foundational phase of stranger anxiety typically begins around the 6-month mark. By 18 months, while stranger anxiety may still be present, it tends to decrease as the child's social skills and understanding of the world expand.

Thus, the correct milestone for the onset of stranger anxiety is closely aligned with developmental expectations at 6 months.