COMPARING ACQUISITION RATES OF VOCAL MANDS IN CHILDREN WITH AUTISM: VOCAL ALONE vs. MODIFIED TOTAL COMMUNCATION

Abstract

Total communication (TC) involves the teaching of a manual sign language response while simultaneously presenting the corresponding vocal stimulus. TC procedures have been shown to increase the acquisition of vocal responding for children with autism spectrum disorder (ASD). This study attempted to systematically replicate the findings in Carbone et al. (2006), who found TC training to have a superior advantage over vocal alone (VA) procedures in the acquisition of vocal tacts. An alternating treatments design with initial baseline was implemented to compare two conditions in teaching vocal mands to children with ASD. In the VA condition, the researcher presented a vocal prompt to evoke vocal behavior. In the modified total communication (MTC) condition, the researcher presented the vocal prompt along with the corresponding manual sign. Participants were only required to vocally respond to produce reinforcement in both conditions. Sign language responses also produced reinforcement. Four children diagnosed with ASD and varying speech delays participated in this study. A multiple stimulus without replacement (MSWO) preference assessment (DeLeon & Iwata, 1996) was used to identify each participants’ preference to 15- 20 different stimuli. Following baseline, one to two highly preferred target stimuli were assigned to each condition. Four sessions were conducted during the intervention phase, two sessions of the VA condition and two sessions of the MTC condition. Conditions were counterbalanced by alternating each session with no more than two consecutive sessions of the same condition introduced first to control for sequential confounds. Sessions included three trial presentations of each stimulus. Sessions took place one to three times a week. Previous research suggested MTC to have an advantage in higher acquisition rates of vocal responses than the VA condition. The study outcome led to mixed results; three participants demonstrated slightly better acquisition of vocal mands in the MTC condition compared to the VA condition. The MTC condition also yielded slightly better acquisition of full word vocalizations and independent vocalizations for two participants. Results of this study were marginal and inconsistent but could suggest MTC training to have a slight advantage in the acquisition of vocal responses in individuals with speech delays. It also appears that teaching sign language to individuals with communication delays does not hinder natural speech development. Keywords: Vocal alone, total communication, modified total communication, manding, vocal prompt, alternating treatments design, autism spectrum disorder