Inconsistency of mothers' feedback and toddlers' misbehavior and negative affect.

The general hypothesis that mothers' inconsistent discipline can cause children to misbehave was examined. Mothers, who were otherwise engaged in a telephone conversation, were instructed to respond to toddlers' inappropriate demands for attention with either consistent reprimands or with one of a variety of inconsistent strategies. Reprimanding half of the child's demands and providing positive attention to the rest of the demands resulted in high rates of both demands for mothers' attention and children's negative affect. Reprimanding half the children's demands and ignoring the other demands did not have deleterious effects nor did reprimanding and attending to the same demand half of the time and ignoring the other demands. Thus, clear, positive feedback for inappropriate demands is a type of inconsistent discipline that can cause normal toddlers to become "terrible twos."