Babies understand thought process of others at 10 months old, research suggests. FULL STORY. At 10 months, babies start to understand another person's thought process, providing new insights on how humans acquire knowledge and how communication develops, new research suggests. Credit: Â© Irina Magrelo / Fotolia. New research from the University of Missouri indicates that at 10 months, babies start to understand another person's thought process, providing new insights on how humans acquire knowledge and how communication develops.