Consider a related emotion, anger. Experts know that young infants are capable of experiencing and expressing this emotion. Most parents also know this, often better than we care to admit. But if you are somehow unacquainted with the phenomenon of anger, see what happens to a baby when you offer him his favorite toy and then withdraw it just as he is about to reach for it. Try putting a baby in a swing but do not give him a push. Refuse to pick him up so that he cannot see his mother’s smiling face as she approaches him after a long day’s separation.
These events provoke anger in infants, but only if they have matured to the point where they are intellectually capable of having expectations. Having an expectation requires months of growth during which time infants develop cognitive, or intellectual, skills that gradually enable them to think abstractly. Memory develops so that an infant can think about ideas in his mind, not merely tangible objects in his hands.
Once an infant is able to expect the enjoyment of having an object, such as a toy, he will be enraged by being deprived of it. If he is accustomed to pleasurable experiences, such as being rocked in a swing or observing his mother’s approach, he will be angered if they are denied him. Anger ensues from instances where expectations of pleasurable events are violated, or what we call frustration. So infants old enough to have expectations are also old enough to be frustrated and to get angry. Now consider the situation where an infant does not express anger and has not been frustrated. We -don’t infer that he is incapable of anger; instead, we can only gather that he has not been frustrated.