Michael (age 5 and autistic) uses the Picture Exchange Communication System (PECS) to request a preferred book from the therapist. Notice that 1.) Michael gets out of the chair and walks to the PECS book. 2.) Michael selects the correct picture, which is randomly placed among three "distractor" pictures. 3.) Michael presents the picture to the therapist. 4.) After each trial, the therapist randomly rearranges the "desired" picture among the three distractors. When Michael's school sytem started PECS training, they reduced the number of distractors, and never used random placement of the "desired" picture. Eventually, they totally deprogrammed Michael.