Increasing Vocalizations In Children with Autism Through Extinction of Previously Acquired Signed Requests

Background: Deficits in speech have been identified as one of the most common complaints of parents of children diagnosed with autism.  Although much research supports the use of behavioral strategies such as reinforcement and shaping for teaching vocal speech one limitation of existing treatments is the lack of procedures for producing vocalizations in children who do not respond to basic behavioral strategies. A new area of study has incorporated the use of extinction procedures to induce vocalizations and other novel responses.  Research has shown that responding during extinction is often characterized by an initial increase in response frequency, duration, and variability. This effect is referred to as an extinction burst and is generally described as a negative result of extinction.  However, extinction bursts may have clinically beneficial applications.  

Objectives: The purpose of experiment one was to assess the effects of reinforcement of vocal requests and extinction of signed requests 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 the effects of extinction of signed requests only after reinforcement of vocalizations during baseline was ineffective in increasing vocalizations.

Methods: In experiment one, Oliver was 3-years old and Sam was 5-years old.  Rate of vocalizations was the dependent variable.  A multiple baseline design across responses was used.  During baseline, access to a preferred item was provided contingent upon correct emission of the previously taught signed response.  No consequences were provided following vocalizations. In treatment, access to the item was provided contingent upon emission of any vocalization.  No consequences were provided following signed responses.  Signed responses contacted extinction conditions.  In experiment two, Ethan was 4-years old. Rate of vocalizations and signed requests were the primary dependent variables. A multiple baseline design across responses was used.  During baseline, access to the item was provided for 10 s or until consumed contingent upon emission of the signed response or any vocalization.  In treatment, access to the item was provided contingent upon emission of any vocalization.   No consequences were provided following signed responses. 

Results: Results of experiment one indicated low rates of vocalizations and high rates of signed requests during baseline.   Upon implementation of extinction of the signed request, the rate of vocalizations increased and remained elevated during subsequent treatment sessions.  In experiment two, Ethan’s rate of vocalizations in baseline did not increase despite direct reinforcement of vocalizations.  Extinction of the signed requests was necessary to obtain elevated rates of vocalizations. 

Conclusions: The failure to acquire vocalizations through established treatment procedures such as shaping and differential reinforcement is a significant clinical concern for children with language deficits and interventions designed to address this concern are relatively understudied.  Little is known regarding how to produce and develop vocalizations in children who do not respond to commonly used procedures making research into new methods to teach vocal language important.