Exclusion Learning and Emergent Symbolic Category Formation in Individuals with Severe Language Impairments and Intellectual Disabilities.

We evaluated formation of simple symbolic categories from initial learning of specific dictated word-picture relations through emergence of untaught or derived relations. Participants were 10 individuals with severe intellectual and language limitations. Three experimental categories were constructed, each containing 1 spoken word (Set A), 1 photograph (Set B), and 1 visual-graphic "lexigram" (Set C). Exclusion-based learning procedures were used to teach first the 3 auditory-visual relations (A-B relations) and then the 3 visual-visual relations (B-C relations) for each category. Seven participants acquired these initial relations. The untaught relations C-B and A-C were then assessed to evaluate the emergence of symbolic categories. Participants demonstrated virtually error-free performances on C-B and A-C derived relations. The study helps to define operationally a highly useful procedural path for systematic instruction in symbolic functioning for persons with intellectual and language disabilities associated with autism and other neurodevelopmental disorders.