Doctoral Dissertations

Date of Award

12-1999

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Speech and Hearing Science

Major Professor

Lori A. Swanson

Committee Members

Pearl Gordon, Harold Peterson, Stephen Handel

Abstract

Function morphemes assist typically developing (TD) children in segmenting speech, identifying syntactic categories, and mapping meaning onto words, yet function morphemes pose particular difficulty for children with specific language impairment(SLI). This investigation examined the effect of morphosyntactic context on verb comprehension for two groups of telegraphic speakers at the same expressive language stage as measured by mean length of utterance (MLU). The following two research questions were posed. Do young telegraphic speakers show increased verb comprehension given sentences containing a grammatical morpheme compared with sentences containing an im grammatical morpheme, a nonsense syllable, or no morpheme?Do children with SLI differ in verb comprehension for sentences with varying morphosyntactic contexts when compared with younger, MLU-matched TD children?Two MLU-equivalent groups participated, 16 TD children (age = 26 mos.) and 16 children with SLI (age = 48 mos.). Similar to Gerken and McIntosh (1993), a picture selection task was used to test verb comprehension in 4 contexts: grammatical auxiliary(Who is pushing?); omitted auxiliary (Who Φ pushing?); ungrammatical morpheme(Who in pushing?); and nonsense syllable (Who id pushing?). Auditory stimuli were digitally edited to control duration and naturalness.Experimental manipulation of “is” did not result in significant differences across morpheme contexts for either group. Verb comprehension probably was supported by verb lengthening associated with utterance-final position. Verbs also were marked by morpheme -ing. This morphosyntactic cue (i.e., morpheme -ing) may have aided verb comprehension regardless of auxiliary “is” variation. Findings suggest function morphemes are only one among many input cues available to language learners during comprehension, including prosodic, phonological, and contextual cues.Children with SLI had significantly higher verb comprehension than ID childrenacross morpheme contexts. Group differences favoring children with SLI(e.g., chronological age and receptive language) may explain this finding. Despitemorpheme anomalies, children with SLI demonstrated verb comprehension when the input cues were redundant and correlated with meaning. Discrepancies between these results and report of a grammaticality effect by McNamara, Carter, McIntosh, and Gerken(1998) are relevant to theories of SLI regarding limited processing capacity and memory limitations.

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