Firstborn Children

Firstborn children are temporarily only children and thus are exposed to one-to-one speech with their parents. When a new child is born, firstborns and their siblings receive less child-directed speech and are privy to multiparty speech. Specifically, mothers appear to provide more linguistic support and more complex grammatical statements to their firstborns even when their firstborns and latterborns are observed at the same age. Concordantly, firstborn toddlers have larger vocabularies, reach language milestones earlier, and demonstrate more sophisticated grammar than their siblings. The early language competence of firstborns may partially explain the proclivity of firstborns to achieve in school. In contrast, later-born children's skill in conversational speech and their expertise in understanding the mental states of others potentially contribute to their renowned social acumen.

On average, firstborn children have been cited as having higher intelligence levels than later-born children. For example, one study examined scores on the 1965 National Merit Scholarship Qualifying Test and, regardless of family size, the scores tended to be higher for firstborns. The confluence model has been proposed to explain the superior intellectual rankings of firstborns. In this paradigm, a child's intellectual level depends on the average intellectual level of all the family members. When a new child is born into the family, the intellectual environment declines. This model states that, in general, large families have impoverished intellectual climates, as there are many immature minds for several years. Also, age spacing between siblings is an important variable in this theory. Small age differences are beneficial to the first-born in that the firstborn is not exposed to very young siblings for too long. In addition, the firstborn has the opportunity to teach siblings, which facilitates the crystallization of knowledge of the firstborn. Applying the confluence model, if one could choose an ordinal position, one would prefer to be a firstborn with a younger sibling close in age. With its emphasis on average intellectual atmosphere, the confluence model has created much debate.

Some of the implications of the theory have not received support in the literature. For example, additional adults in the household, such as grandparents, do not seem to increase children's IQ as would seem to be predicted by the confluence model. Furthermore, Literature suggests that parents harbor expectations of how firstborns should behave, then act in accordance with those beliefs. During infancy, for example, mothers attend to firstborns by responding to and stimulating them more than latterborns. (Tim Pannell/Corbis) differences found in IQ among firstborns, latterborns, and only children are typically small and unstable.