The study also found that children who participate in more structured activities-including soccer practice, piano lessons and homework-had poorer "self-directed executive function," a measure of the ability to set and reach goals independently.
University of Colorado Boulder psychology and neuroscience Professor Yuko Munakata, senior author of the new study, said executive function is extremely important for children.
She said it helps them in all kinds of ways throughout their daily lives, from flexibly switching between different activities rather than getting stuck on one thing, to stopping themselves from yelling when angry, to delaying gratification.
Munakata said executive function during childhood also predicts important outcomes, like academic performance, health, wealth and criminality, years and even decades later.
For the study, parents of 70 6-year-olds recorded their children's daily activities for a week. The scientists then categorized those activities as either more structured or less structured, relying on existing time-use classifications already used in scientific literature by economists.
In that classification system, structured activities include chores, physical lessons, non-physical lessons and religious activities. Less-structured activities include free play alone and with others, social outings, sightseeing, reading and media time. Activities that did not count in either category include sleeping, eating meals, going to school and commuting.
The study has been published online in the journal Frontiers in Psychology.