Lexical Deficits in Specific
Laurence B. Leonard
In this chapter, we examine the lexical abilities of children with specific language impairment (SLI). These children exhibit a significant deficit in language ability, yet show no evidence of obvious neurological impairment or significant limitations in nonverbal intellectual functioning. In addition, the hearing of these children is within normal limits, and they provide no indication of serious emotional difficulties.
In recent years, the grammatical limitations of children with SLI have received the greatest investigative attention (see reviews by Bishop, 1997; Leonard, 1998). However, many of these children also experience difficulty in learning, understanding, and using words. According to the clinical classification system developed by Rapin and Allen (1983), one subtype of SLI can be characterized as a lexical-semantic subtype. In a study by Korkman and Häkkinen-Rihu (1994), one subgroup of children with SLI seemed to perform especially poorly on naming tasks. Although other studies have not been successful in identifying a subgroup whose problems are limited to lexical difficulties (e.g., Aram & Nation, 1975; Wilson & Risucci, 1986; Wolfus, Moscovitch, & Kinsbourne, 1980), the literature makes it clear that many children with SLI have lexical problems along with difficulties in other areas of language. These lexical limitations are the focus of this chapter.
Problems with the lexicon can cause several types of difficulties for children with language learning limitations. Most obviously, if children fail to