Scale errors Psychologists Judy DeLoache, David Uttal, and Karl Rosengren (2004) report that 18- to 30-month-old children may fail to take the size of an object into account when trying to perform impossible actions with it. At left, a 21-month-old attempts to slide down a miniature slide. At right, a 24-month-old opens the door to a miniature car and tries to step inside.