March 24, 2000

A New Round of Research Rattles Old Ideas of How Infants Interpret the World

By RICHARD MONASTERSKY

Renee Baillargeon spends much of her time conjuring up mice and passing boxes through solid walls. But the magic tricks never get any applause. Her audience hasn't yet mastered the complicated process of slapping one hand against the other.

A professor of psychology at the University of Illinois at Urbana-Champaign, Ms. Baillargeon works with infants as young as 21/2 months old to test what they know about the world they so recently joined. Her experiments and