information:classification, structural:summarization, structural:expansion, stylistic:tone
Onset

Stranger anxiety develops slowly; it does not just appear suddenly. It typically first starts to appear around four months of age with infants behaving differently with caregivers than with strangers. In fact, there is a difference between their interactions with their caregiver and the stranger. They become cautious when strangers are around; therefore, preferring to be with their caregiver instead of the stranger. Around 7–8 months, stranger anxiety becomes more present; therefore, it occurs more frequently at this point. Infants start to be aware of their environment and they are aware of their relationships with people; so, stranger anxiety is clearly displayed. Around this time, children choose and prefer to be with their primary caregiver. As a child's cognitive skills develop and improve, typically around 12 months, their stranger anxiety can become more intense. They display behaviors like running to their caregiver, grabbing at the caregiver's legs, or demanding to be picked up. Children seem also to respond more positively to a person who gives positive reinforcements and more negatively to a person who gives negative reinforcements.