Evaluation of a Blocked-Trials Procedure to Establish Complex Stimulus Control over Intraverbal Responses in Children with Autism.

We evaluated the use of a blocked-trials procedure to establish complex stimulus control over intraverbal responses. The participants were four young boys with a diagnosis of autism who had struggled to master intraverbals. The blocked-trials procedures involved presentation of stimuli in separate trial blocks. The trial blocks gradually reduced in size contingent upon correct responding, until the stimuli were presented in quasi-random order. All participants acquired multiple discriminations with the blocked-trials procedure, although additional procedures were needed to teach the first discrimination with two participants. Following acquisition of multiple discriminations, two participants acquired a novel discrimination with quasi-random presentation of stimuli, and a third participant demonstrated discriminated responding in intraverbal probes.