"When you throw something slowly to a child, you think you're doing them a favour by trying to be helpful," said Terri Lewis, professor of psychology at McMaster University. "Slow balls actually appear stationary to a child."

This explains why a young child holding a bat or a catcher's mitt will often not react to a ball thrown toward her, prompting flummoxed parents to continue throwing the ball even slower. By adding a little speed to the pitch, Lewis and her team found that children were able to judge speed more accurately. There are several reasons for the phenomenon.

"Our brain has very few neurons that deal specifically with slow motion and many neurons that deal with faster motion," says Lewis. "Even adults are worse at slow speeds than they are at faster speeds. The immature neurons in a child's brain make a child especially poor at judging slow speeds -- immaturity disadvantages the few neurons that are responsible for seeing slow speeds more so than the many neurons responsible for seeing faster speeds. Once the brain develops to maturity, it becomes more adept at handling slower speeds."