by Mark Hansen
A group of test subjects ages 10 to 30 is asked to solve a puzzle. It involves re arranging a stack of colored balls on placeholders using as few moves as possible. Each wrong move requires extra moves to undo it.
The test is designed to measure impulse control. Adolescents tend to start moving balls almost immediately, which usually necessitates rearranging later. Adults, however, tend to take more time to consider their first move, which generally allows them to solve the puzzle on their first try.