Mapping the meanings of novel visual symbols by youth with moderate or severe mental retardation.

The word-learning ability of 12 school-age subjects with moderate or severe mental retardation was assessed. Subjects had little or no functional speech and used the System for Augmenting Language with visual-graphic symbols for communication. Their ability to fast map novel symbols revealed whether they possessed the novel name-nameless category (N3C) lexical operating principle. On first exposure, 7 subjects were able to map symbol meanings for novel objects. Follow-up assessments indicated that mappers retained comprehension of some of the novel words for up to delays of 15 days and generalized their knowledge to production. Ability to fast map reliably was related to symbol achievement status. Implications for understanding vocabulary acquisition by youth with mental retardation were discussed.