From the Star-Ledger:
"'I think we really underestimate how much young children take in,' said Tovah Klein, of the Barnard College Center for Toddler Development, one of the study’s authors. 'We tend to overlook the emotional needs of young children.'
Her researchers interviewed 180 preschoolers and their parents nine to 12 months after the attacks. None of the children lost a parent in the attacks, but all lived near the World Trade Center and had either seen, heard, felt or smelled its destruction."