In other words, at what age do children grasp the fact that they, like all humans, possess as mind that filters their experience of reality through the selective process of memory. He then pretends Daddy and Mommy are looking for the football.
Daddy looks under the couch and sees the ball.
Almost every child answers affirmatively. Lyon then has Mommy look on top of the couch where the football is not visible. They come home and now neither one can know where the football is. Children ages 4 and older seem to formally understand that the character who knew before, Daddy, is the one who forgot. An underlying assumption of Tom Lyon's research is that young children are develop-mentally limited in their ability to think like adults.