Born First, Born Smarter? Zajonc, R.B., & Markus, G.B. (1975) Birth order and intellectual development. Psychological Review, 82 74-88
Studies have shown that first born children tend to be: • More verbally articulate • Less impulsive • More active • Better performers in school • More likely to go to college • Tend to have a greater need to achieve • Score higher on tests of intelligence & aptitude
Why? • Genetic composition may change with birth order • Due to age of mother • Chemical alterations caused by previous births
However, social scientists have rejected these nature explanations in favor of nurture, environmental based theories Environment can have a strong influence on intellectual capacities and abilities
Birth order is an environmental factor present in the development of all children • The first-born child will usually experience a completely different environment (usually consisting of two parents) than the second-born child (consisting of two parents and one child) • The resulting developmentalsituation for the second child is considerably different
Robert Zajonc and Gregory Markus • Confluence Theory • Developed a theory explaining the relationship between birth order and intelligence • It was unique in that their theory was applied to other researchers’ data
Theoretical Propositions • Average intellectual climate • An average of the combined intellectual influences of the family members • Each parent is 100 points • Infants start out with 0 points • 5 intellectual points are added per year
Methods and Results • Used a hypothetical family with ten children
Methods and Results • Their hypothesis was mostly supported
Exceptions • The only-child effect • The last-child effect
Discussion • The effect of gaps • The contributions of older siblings • Intellectual climate raises after the fifth child • The last child effect
Discussion • Parents’ dilemma • Intellectual climate is not the only determinant of intellectual ability ?
Criticisms • Statistical Significance? • Measured within instead of across families • Low-IQ parents have been making large families • Large families do not make low-IQ children • Resource-dilution theory
By the Way • Don’t be depressed . . . • Downsides to being first • Advantages to being later
Class Discussion • Would you use this study to plan your family? • Does this apply to your family or other families that you know? • What are your feelings on the nature-nurture interaction and intelligence?