When infants develop object permanence certain fears start to develop (see article on object permanence). Stranger wariness is the caution and concern that infants feel when they encounter an unfamiliar person. “Who is this stranger?” Stranger anxiety peaks between 6 and 12 months and keeps going to age 2 or 3. It shows that infants have memory; they know who is familiar to them and who is not (Berger, 2018; Feldman, 2014).
An example of this is when young children are at Disneyland for the first time and they see Mickey or Minnie Mouse in character. At age 1 these characters are so huge and it can freak them out, which is not the reaction that the parents are expecting. Children grow out of it as they get more used to seeing Mickey and Minnie in books and on TV and they know who they are.
Berger, K. S. (2018). The developing person: Through Childhood and adolescence (11th
ed.). New York, NY: Worth.
Feldman, R. S. (2014). Child development: A topical approach. Boston, MA: Pearson.