Running head: EXTINCTION INDUCED VOCALIZATIONS An Investigation of Extinction Induced Vocalizations

Children with autism have significant communication delays. Although some children develop vocalizations through shaping and differential reinforcement, others rarely exhibit vocalizations, and alternative methods are targeted in intervention. However, vocal language often remains a goal for caregivers and clinicians. Thus, strategies to increase frequency of vocalizations are needed. In the present study we examined the effect of extinction of previously acquired signed mands on vocalizations in three children diagnosed with autism. Experiment one examined the effects of differential reinforcement of vocalizations and extinction of signed mands combined. In experiment one, it was unknown whether reinforcement of vocalizations alone could have produced the effects; therefore, experiment two isolated the effects of reinforcement and extinction by reinforcing vocalizations in baseline. An increase in rate of vocalizations occurred following application of extinction of signed mands and differential reinforcement of vocalizations in experiment one; and following extinction of signed mands in experiment two. DESCRIPTORS: autism, extinction, communication training, verbal behavior, behavioral variability EXTINCTION INDUCED VOCALIZATIONS 3 An Investigation of Extinction Induced Vocalizations Deficits in speech development have been identified as one of the most common presenting complaints of parents of children diagnosed with autism (De Giacomo & Fombonne, 1998). Although much research supports the use of reinforcement and shaping procedures for teaching vocal imitation (Baer, Peterson, & Sherman, 1967; Garcia, Baer, & Firestone, 1971; Lovaas, Berberich, Perloff, & Schaeffer, 1966; Schroeder & Baer, 1972), there is a lack of procedures for producing vocalizations in children who do not respond to shaping and differential reinforcement. Shaping may not be effective for children who emit a low rate of vocalizations because there is very little behavior to reinforce and shape. Thus, lack of methods for producing vocalizations in individuals who emit a low rate of or no vocalizations represents a critical gap in behavioral literature. A relatively new area of study has incorporated the use of extinction procedures to induce vocalizations and other novel responses (Grow, Kelley, Roane, & Shillingsburg, 2008). Research has shown that responding during extinction is often characterized by an initial increase in response frequency, duration, and variability (Galbicka, 1988). This effect is referred to as an extinction burst and is generally described as a negative result of extinction (Lerman, Iwata, & Wallace, 1999). However, extinction bursts may have clinically beneficial applications. Several studies have investigated use of extinction to increase behavioral variability and thereby produce the emergence of novel appropriate behavior. Duker and Van Lent (1991) demonstrated an increase in the variety of gesture requests emitted by six children with developmental delays by withholding reinforcement for the most frequently used gestures. Additionally, Lalli, Zanolli, and Wohn (1994) induced untrained toy play responses in two children with developmental delays by first teaching one toy play response and subsequently EXTINCTION INDUCED VOCALIZATIONS 4 placing that response on extinction. Results indicated that both participants emitted a wider range of responses when the trained response was placed on extinction. Novel responses that emerged were then reinforced. In a recent article (Grow et al., 2008) effects of extinction on novel communicative behaviors were specifically examined in children with developmental disabilities. In this article, the authors evaluated the efficacy of exposing problem behavior to extinction as a means of inducing response variability and subsequent emergence of appropriate responses. During baseline, no consequences were provided for appropriate communication and problem behavior was reinforced. During the treatment phase, problem behavior was placed on extinction and the first appropriate request that emerged was reinforced. Exposure to extinction for problem behavior produced response variability and high levels of appropriate behaviors occurred and maintained once the response contacted reinforcement. Although this emerging body of literature shows advantageous outcomes of the extinction burst, no research has been conducted assessing the effectiveness of the extinction burst in producing vocalizations in individuals who emit low rate or no vocalizations. The overall purpose of the present investigation was to assess the effect of extinction of previously acquired signed mands (requests) on vocalizations in children with limited vocal repertoires. The purpose of experiment one was to assess the effects of differential reinforcement of vocal mands and extinction of signed mands on the rate of vocalizations in two children with autism. The purpose of experiment two was to determine whether the effects obtained in study one could have been obtained through reinforcement of vocalizations or whether the effects were due to extinction. Therefore, experiment two examined effects of extinction of signed mands only after EXTINCTION INDUCED VOCALIZATIONS 5 reinforcement of vocalizations during baseline was ineffective in increasing rates of vocalizations.