Japanese society may become increasingly polarized between a small elite and the rest of the population, if indications in a recent survey of schoolchildren's study habits hold up.

The survey, by a group of researchers at Ochanomizu University in Tokyo, shows that children with strong scholastic aptitudes or who are enrolled at good schools study more than those with less ability, highlighting a growing gap in the classroom that could translate into greater economic inequality down the road.

In June and July, the group asked thousands of fifth-graders, second-year junior high school students and high school juniors how much time they spend studying on weekdays and compared the results with those of earlier surveys.