GrammaticalTenseDeficits in Children ' WithSll and NonspecificlanguageImpairment : RelationshipsWithNonverbal IQ OverTime

The relationship between children's language acquisition and their nonverbal intelligence has a long tradition of scientific inquiry. Current attention focuses on the use of nonverballQ level as an exclusionary criterion in the definition of specific language impairment (SU).Grammatical tense deficits are known as a clinical marker of SU, but the relationship with nonverbal intelligence below the normal range has not previously been systematically studied. This study documents the levels of grammatical tense acquisition (for third-person singular -5, regular and irregular past tense morphology) in a large, epidemiologically ascertained sample of kindergarten children that comprises 4 groups: 130 children with SU, 100 children with nonspecific language impairments (NUl, 73 children with low cognitive levels but language within normal limits (LC),and 117 unaffected control children. The study also documents the longitudinal course of acquisition for the SU and NU children between the ages of 6 and 10 years. The LCgroup did not differ from the unaffected controls at kindergarten, showing a dissociation of nonverbal intelligence and grammatical tense marking, so that low levels of nonverbal intelligence did not necessarily yield low levels of grammatical tense. The NU group's level of performance was lower than that of the SU group and showed a greater delay in resolution of the overgeneralization phase of irregular past tense mastery, indicating qualitative differences in growth. Implications for clinical groupings for research and clinical purposes are discussed.