Grammatical morphology as a source of early number word meanings
- aDivision of Psychology and Language Sciences, University College London, London WC1N 1PF, United Kingdom;
- bDepartment of Health Rehabilitation Sciences, King Saud University, Riyadh, Saudi Arabia 11451;
- cDepartment of Psychology and
- fDepartment of Linguistics, University of California at San Diego; La Jolla, CA 92116;
- dResearch Center for Humanities (Language and Cognitive Science), University of Nova Gorica, SI-5000 Nova Gorica, Slovenia; and
- eBrain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139
See allHide authors and affiliations
Edited by Susan E. Carey, Harvard University, Cambridge, MA, and approved September 30, 2013 (received for review July 19, 2013)

Significance
Languages vary in how they grammatically mark number (e.g., in nouns, verbs, and so forth). We test the effects of this variability on learning number words—for example, one, two, three—by investigating children learning Slovenian and Saudi Arabic, which have singular-plural marking, but also dual marking (for sets of two). We find that learning the dual is associated with faster learning of the meaning of two than in any previously studied language, even when accompanied by less experience with counting. We conclude that although exposure to counting is important to learning number word meanings, hearing number words used outside of these routines—in the quantificational structures of language—may also be highly important in early acquisition.
Abstract
How does cross-linguistic variation in linguistic structure affect children’s acquisition of early number word meanings? We tested this question by investigating number word learning in two unrelated languages that feature a tripartite singular-dual-plural distinction: Slovenian and Saudi Arabic. We found that learning dual morphology affects children’s acquisition of the number word two in both languages, relative to English. Children who knew the meaning of two were surprisingly frequent in the dual languages, relative to English. Furthermore, Slovenian children were faster to learn two than children learning English, despite being less-competent counters. Finally, in both Slovenian and Saudi Arabic, comprehension of the dual was correlated with knowledge of two and higher number words.
Footnotes
↵1A.A. and J.S. contributed equally to this work.
- ↵2To whom correspondence should be addressed. E-mail: barner{at}ucsd.edu.
Author contributions: A.A., J.S., C.D., F.M., R.Ž., T.O., and D.B. designed research; A.A., J.S., C.D., F.M., R.Ž., and D.B. performed research; A.A., J.S., C.D., F.M., R.Ž., T.O., and D.B. analyzed data; A.A., J.S., F.M., R.Ž., T.O., and D.B. wrote the paper; A.A. designed experiments and collected data for Saudi Arabic; J.S. designed studies and collected data for Slovenian and English and conducted statistical analyses; C.D. designed studies and oversaw data collection for Saudi Arabic; F.M. and R.Ž. designed studies and oversaw data collection for Slovenian; T.O. designed studies for Slovenian and conducted data analyses for all studies; and D.B. designed studies for Slovenian and English and oversaw data collection in English.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1313652110/-/DCSupplemental.
Freely available online through the PNAS open access option.