For nine years, the researchers annually canvassed parents in about 200 White, European-American families about their teens' decisions.
Mothers and fathers reported on who made decisions in eight areas of their children's lives, including chores, appearance, curfew/bedtime, health, schoolwork, social life, activities, and money.
The researchers noted that young people's input into decisions increased gradually from ages 9 to 14, and then surged from ages 15 to 20.
Moreover, young people had more input into decisions about appearance, activities, schoolwork, and social life than about chores, health, and curfew.
It was found that in late adolescence (ages 18 to 20), decisions about money and health were still being made jointly by parents and adolescents, suggesting that autonomy developed more gradually for these types of decisions.
The study also revealed that certain children had more decision-making autonomy than others.
Those with more decision-making autonomy included girls, young people whom their parents said were easy to supervise, and children with better-educated parents.
However, there wasn't a single, universal pattern in the development of decision making.
Instead, decision-making autonomy depended on what kinds of decisions youngsters faced, and on their personal and family circumstances.