In the following paper, two experiments are reported based on the relation between adult approvals as conditioned reinforcers and the number of vocal verbal operants, specifically tacts, mands, wh questions, sequelics, and conversational units emitted by children diagnosed with developmental disabilities. In Experiment I, following an experimental…

The discrimination of the onset of joint control is an important interpretive tool in explaining matching behavior and other complex phenomena, but the difficulty of getting experimental control of all relevant variables stands in the way of a definitive experiment. The studies in the present issue of "The Analysis of Verbal Behavior" illustrate…