Antecedent manipulations in a tangible condition effects of stimulus preference on aggression

After a functional analysis indicated that aggression of an 8-year-old boy with autism was maintained by access to preferred items, antecedent manipul ations involving the relative preference of restrict-ed and noncontingently available stimuli were conducted. Restricting highly preferred items evoke d the highest rates of aggression regardless of the preference level of the noncontingently available alternative items. Restricting less preferred st imuli was associated with moderate rates of aggression even when the altern ative items were more preferred.