Multiple-object tracking involves simultaneously tracking positions of a number of target-items as they move among distractors. The standard version of the task poses special challenges for children, demanding extended concentration and the ability to distinguish targets from identical-looking distractors, and may thus underestimate children's tracking abilities. As a result, a modified version of the task called "Catch the Spies" was developed. Participants tracked one to four moving "spies" (targets) that had "disguised" themselves so that they could blend in with a crowd of 10 people (happy-faces). Tracking accuracy was measured in five age groups (6, 8, 10, 12, and 19 years old). All performed well above chance though there were age-related increases in the number that could be tracked at once. Overall, when the effects of age were statistically controlled, tracking performance was significantly better for action videogame players than non-players, and marginally better for action-sports participants than non-participants.