With regard to temperament, infants who exhibit a pattern of withdrawal from unfamiliar objects, negative mood, and low levels of activity are called what?

These infants are called slow to warm up. These infants do not join in activity immediately, instead they observe others before deciding to join in. They are usually withdrawn from most people, but are willing to open up to people they trust. This temperament is not something an infant can choose, rather it is something they are born with. These infants are much more uncomfortable to change than others, but are more likely to think before acting.