Assignment task: Apsychologist wants to learn more about aggression in preschoolers. He gets permission to visit a preschool in order to conduct h research and is able to observe the children while they are on the playground. He watches the children while standing in the classroom, looking through the window (the children don't know they're being observed) and carefully records and classifies instances of their aggressive behavior. Why did the psychologist conceal himself while making the observations?