title: Longitudinal relationships between lexical and grammatical development in typical and late-talking children.
abstract: OBJECTIVE
  This study examined the longitudinal relationships between lexical and grammatical development in typically developing (TD) and late-talking children for the purposes of testing the single-mechanism account of language acquisition and comparing the developmental trajectories of lexical and grammatical development in late-talking and TD children.
  
  
  METHODS
  Participants included 30 children identified as late talkers (LTs) at 2;0 (years;months), and 30 TD children matched on age, nonverbal cognition, socioeconomic status, and gender. Data were collected at 5 points between 2;0 and 5;6.
  
  
  RESULTS
  Cross-lagged correlational analyses indicated that TD children showed evidence of bidirectional bootstrapping between lexical and grammatical development between 2;0 and 3;6. Compared with the TD group, LTs exhibited less evidence of syntactic bootstrapping. Linear mixed-effects modeling of language sample data suggested that the relationship between lexical and grammatical growth was similar for the 2 groups.
  
  
  CONCLUSIONS
  Lexical and grammatical development were strongly related in both groups, consistent with the single-mechanism account of language acquisition. The results were mixed in terms of finding longitudinal differences in lexical-grammatical relationships between the TD and late-talking children; however, several analyses suggested that for late-talking children, syntactic growth may be less facilitative of lexical development.
authors.affiliation: University of Wisconsin, Madison , USA. maura.moyle@marquette.edu
authors.forename: Maura Jones
authors.initials: MJ
authors.lastname: Moyle
authors.forename: Susan
authors.initials: S
authors.lastname: Ellis Weismer
authors.forename: Julia L
authors.initials: JL
authors.lastname: Evans
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Lindstrom
mesh_terms: D000367:Age Factors; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007805:Language Development Disorders / Q000175:diagnosis*; D007807:Language Tests; D008037:Linguistics; D008297:Male; D012720:Severity of Illness Index; D014825:Vocabulary