Easy one. She'd seen decorating statues, common in theaters, that after greek fashion, have no discernable pupils.

http://rs.musee-rodin.fr/filestore/3/7/5/4_1812f2e6c7f4977/3754_8a8973786c13fea.jpg

They look like they watch you, and a child has no trouble confusing them with real people. I know, because I used to be terrified of those statues.