Toddlers' Verb Lexicon Diversity and Grammatical Outcomes Purpose The goals of this study were to quantify longitudinal expectations for verb lexicon growth and to determine whether verb lexicon measures were better predictors of later grammatical outcomes than noun lexicon measures. Method Longitudinal parent-report measures from the MacArthur-Bates Communicative Development Inventory (Fenson et al., 2007) from ... Research Article
Research Article  |   January 01, 2016
Toddlers' Verb Lexicon Diversity and Grammatical Outcomes
 
Author Affiliations & Notes
  • Pamela A. Hadley
    University of Illinois at Urbana–Champaign
  • Matthew Rispoli
    University of Illinois at Urbana–Champaign
  • Ning Hsu
    University of Illinois at Urbana–Champaign
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication. ×
  • Correspondence to Pamela A. Hadley: phadley@illinois.edu
  • Editor: Marilyn Nippold
    Editor: Marilyn Nippold×
  • Associate Editor: LaVae Hoffman
    Associate Editor: LaVae Hoffman×
Article Information
Development / Research Issues, Methods & Evidence-Based Practice / Language Disorders / Specific Language Impairment / Research Articles
Research Article   |   January 01, 2016
Toddlers' Verb Lexicon Diversity and Grammatical Outcomes
Language, Speech, and Hearing Services in Schools, January 2016, Vol. 47, 44-58. doi:10.1044/2015_LSHSS-15-0018
History: Received April 8, 2015 , Revised July 20, 2015 , Accepted August 14, 2015
 
Language, Speech, and Hearing Services in Schools, January 2016, Vol. 47, 44-58. doi:10.1044/2015_LSHSS-15-0018
History: Received April 8, 2015; Revised July 20, 2015; Accepted August 14, 2015

Purpose The goals of this study were to quantify longitudinal expectations for verb lexicon growth and to determine whether verb lexicon measures were better predictors of later grammatical outcomes than noun lexicon measures.

Method Longitudinal parent-report measures from the MacArthur-Bates Communicative Development Inventory (Fenson et al., 2007) from ages 21 to 30 months from an archival database were used to model growth in common noun and verb lexicon size for 45 typically developing toddlers. Communicative Development Inventory growth coefficients and 24-month measures of lexical diversity from spontaneous language samples were used to predict 30-month grammatical outcomes on the Index of Productive Syntax (Scarborough, 1990).

Results Average verb growth was characterized by 50.57 verbs at 24 months, with linear growth of 8.29 verbs per month and deceleration overall. Children with small verb lexicons or slow linear growth at 24 months accelerated during this developmental period. Verb lexicon measures were better predictors of grammatical outcomes than noun lexicon measures, accounting for 47.8% of the variance in Index of Productive Syntax scores. Lexical verb diversity in spontaneous speech emerged as the single best predictor.

Conclusion Measures of verb lexicon size and diversity should be included as part of early language assessment to guide clinical decision making with young children at risk for language impairment.

Acknowledgments
Data collection for the archival database used in this study was supported by National Science Foundation grant BCS-08-22513 awarded to Matthew Rispoli. Portions of this article were previously presented at the 2013 Symposium for Research in Child Language Disorders, Madison, Wisconsin. We extend sincere appreciation to the parents and children who made the work possible and to Paula Acuña and Megan McKenna for their contributions to the data analysis.
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