Overcoming an autistic child's failure to acquire a tact repertoire.

A 6-year-old nonvocal autistic girl who had acquired over 30 signs as mands (requests), simple intraverbals (English-sign translations), and imitative responses repeatedly failed to acquire a tact (labeling) repertoire. It was speculated that the verbal stimulus "What is that?" blocked the establishment of stimulus control by nonverbal stimuli. When procedures to transfer stimulus control from verbal to nonverbal stimuli were implemented, the subject quickly learned to tact all 18 target stimuli.