Vocabulary competence in first- and secondborn siblings of the same chronological age 1
We explored vocabulary competence in 55 firstborn and secondborn sibling pairs when each child reached 1;8 using multiple measures of maternal report, child speech, and experimenter assessment. Measures from each of the three sources were interrelated. Firstborns' vocabulary competence exceeded secondborns' only in maternal reports, not in child speech or in experimenter assessments. Firstborn girls outperformed boys on all vocabulary competence measures, and secondborn girls outperformed boys on most measures. Vocabulary competence was independent of the gender composition and, generally, of the age difference in sibling pairs. Vocabulary competence in firstborns and secondborns was only weakly related.(Published Online December 1 2004)
(Received April 4 2003)
(Revised January 16 2004)
c1 Marc H. Bornstein, Child and Family Research, National Institute of Child Health and Human Development, National Institutes of Health, Suite 8030, 6705 Rockledge Drive, Bethesda MD 20892-7971, USA. e-mail: Marc_H_Bornstein@nih.gov
1 We thank K. M. Painter and C. Varron for assistance.