Topography-versus selection-based responding: Comparison of mand acquisitions in each modality.

This study examined the acquisition of a mand repertoire by one child with pervasive developmental disorder and ADHD. The subject was taught to request preferred items using American Sign Language (a topographybased response form) and the Picture Exchange Communication System (a selection-based form). There were four types of sessions: (1) training session for PECS, (2) training session for sign language, (3) test for generalization of the PECS words, and (4) test for generalization for the sign words. The number of trials to meet criterion and the occurrence of spontaneous emissions of the taught words was recorded. Also, the same word was taught for five days in both the PECS and the sign session and the results were recorded. It was found that the selection- based verbal response technique (PECS) was more effective in all areas. This finding contradicts the results of previous studies, suggesting that further research is needed. ********** The differences between two types of verbal responding have introduced the need for further research and clarification. These two forms, known as topography- based (TB) verbal responding and selection- based (SB) verbal responding, will be clarified as outlined in Michael's paper (1985) which makes a clear distinction between the two forms. They also have been addressed by some limited research (Hodges & Schwethelm, 1984; Potter, Huber & Michael, 1997; Sundberg & Sundberg, 1990; Wraikat, Sundberg & Michael, 1991), but more should be done in order to establish the most effective method to use with individuals with verbal impairments. There is a need to examine the efficacy of the two types of verbal behavior and to clarify the distinctions between the two, so that we can gain a better understanding of verbal behavior. Also, more empirical research will help us create better programs for individuals. This paper offers an in depth look into the efficacy of training a child with pervasive developmental disorder and ADHD's mand repertoires, comparing a method using sign language and a method using the Picture Exchange Communication System (PECS). This study contributed to the current research that continues to examine differences and looks for ways of designing better techniques for individuals with verbal impairments. LITERATURE REVIEW Topography- based verbal behavior was described by Michael (1985) as emitting a response that is specified by (or whose consequences are contingent upon) particular characteristics of topography. Examples of TB verbal responding include sign language, writing, or speaking. Michael described selection-based verbal behavior as verbal behavior that consists of pointing to or selecting a stimulus in an array. Examples of SB techniques include communication boards and PECS. There has been an increase in the use of SB techniques, particularly with children who have severe language delays (Potter & Brown, 1997). However, there is no empirical research to support this strategy. Communication boards usually consist of several pictures on one board. The child must point to the picture of the requested item or activity in order to gain access to it. PECS is a method that requires the subject to scan an array of pictures, select one, and hand it to a communicative partner. For more information about TB and SB formats, see Glennan and DeCoste (1997). Recent research has found that TB verbal responding produced better overall results than SB verbal responding (Schafer, 1993; Sundberg & Sundberg, 1990). Most of those studies focused on differences in acquisition and accuracy of tact and intraverbal relations. Some reasons for recommending TB systems are practicality (no additional equipment needed), iconicity (the sign bears a resemblance to the referent), and assistance in promoting vocal development (Shaffer, 1993). The type of SB verbal responding (PECS) has not been compared with a TB verbal responding method. …