Jealousy works in much the same way. Frustrated expectations precipitate jealousy just as they might precipitate anger. In the case of jealousy, however, the expectations associated with jealousy are specically related to what psychoanalysts have named a “love object,” such as a spouse or parent, and how she gives out attention to other individuals. This holds true for adults as well as infants. Infant jealousy is usually a response to a parent’s directing attention toward a sibling. Firstborn children are upset by this because they develop the expectation of receiving exclusive parental attention since there are no other children present during the course of the day. Later-born children also develop expectations that spark jealousy. Even though they have not received exclusive parental attention, they have enjoyed the special status of being the youngest child in the family and of receiving preferential treatment, because parents tend to give the youngest child the most attention. Thus, regardless of whether an infant is a rstborn or a later-born child, during early infancy he becomes accustomed to being treated as the “number one” baby. For the “number one” baby, parental attention toward another baby violates her expectations, which leads to a special kind of frustration, known as jealousy.
Anger and jealousy, like all emotions, -don’t just snap into place. Newborns start off capable only of simple feelings of pleasure and pain. Through increased experience and cognitive maturation, these sensations are elaborated and rened into various distinct emotions. Just as infants do not know how to run without rst learning how to sit, stand and walk, they do not instantaneously “develop” jealousy in the precise moment when a sibling is initially presented. Jealousy emerges through a gradual, though invisible, developmental process in which infants slowly acquire certain kinds of expectations. Through their experiences with parents, infants come to expect parental attention and they expect it to have certain qualities. Happy babies expect it to be plentiful, prompt, predictable and tender. Finally, infants expect parental attention to be exclusive, or at least preferential. The process of emotional development that evolves over a period of years is still not fully understood, but it is clear that a simple form of jealousy is established by the rst birthday, even though infants have never met their future siblings and have never witnessed their parents attending to another child.