Ten Rett syndrome (RS) girls and 10 control girls executed an attentional task in which a complex stimulus was shown followed by individual stimuli presented with distractors. Participants had to discriminate previously presented stimuli from distractors. RS girls carried out the task both in a condition with the containment of stereotypies and in a no-containment condition. Overselectivity occurred in RS since patients failed to discriminate about 1/3 of the individual stimuli. There were no statistical differences with respect to the number of correct responses in the two conditions; RS girls learned quickly when their stereotypies were contained as opposed to when the containment of stereotypies was lacking. (Contains 2 figures and 6 tables.)