Stimulus Structure Enhancement of Visual Symbol Detection in AAC

Funded by the National Institute of Child health and Human Development, 5P01HD025995-20

Krista Wilkinson

A child's academic, social, and vocational potential is compromised when that child cannot express him or herself or does not understand what is being said (NJC, 1992). Frustration in communication often results in challenging behaviors that disrupt both the child's own learning and that of peers. Such basic communication functions are especially difficult for those with significant ID/DD (Light, 1997), yet children with significant ID/DD are often excluded from critical intervention services due to their poorly understood learning support needs and an incorrect assumption that they cannot benefit from communication intervention (see, e.g., Cole el al., 1999; NJC 2002). As a result, this population remains largely under-served.

Communication intervention can offer conventional forms of communication and reduce challenging behaviors (Durand, 1993; Petty et al., 2009). One body of clinical practice involves visual aids such as communication books or high technology devices from which the user selects symbols to produce messages; these are often called aided augmentative and alternative communication (aided AAC; Beukelman & Mirenda, 2005).

While aided AAC has transformed the lives of many individuals with significant disabilities, including those with autism spectrum disorders, empirical reports have also confirmed clinical observations that these AAC interventions are not uniformly successful (Culp et al., 1986; Phillips & Zhao,1993). Johnson et al (2006) conducted factor analysis on surveys from 275 clinicians to characterize the reasons why some users adopt their systems readily, while others struggle. Clinicians reported that success was predicted by "system characteristics and fit," a factor that included ease of physical access to the device and the appropriateness or match of vocabulary content to cognitive and social profiles of the user. Abandonment was predicted by a "poor fit" on these same physical access and vocabulary-related dimensions.

Another dimension that likely affects success is the quality of the match between the physical configuration of the AAC display and the user’s sensory processing capabilities. In oral language interventions, it has long been recognized that optimal aural/oral interventions benefit from an understanding of how children process the auditory signals. Most aided AAC systems rely on a visual modality. Given that the signal is visual, it seems logical to suggest that optimal aided AAC interventions should involve an understanding of how children process visual information. Yet the importance of establishing an optimal match between a display's characteristics and the visual-perceptual functioning of its user has been largely overlooked. In addition, virtually nothing is known about visual processing in individuals with ID/DD, and the evidence available is often contradictory. It seems likely that at least some of AAC displays currently in use are poorly matched to the visual processing skills of their users.

This research seeks to examine visual processing of aided AAC displays in order to optimize the construction of such systems for individuals with significant disabilities. The research will lead to a greater understanding of the unique visual processing demands of aided AAC, and the effects of these demands on communication by individuals with significant intellectual disabilities.