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HomeLiteracy/ESLComparing Child Languages

Comparing Child Languages

Clifton Pye suggests a comprehensive approach to crosslinguistic research

At the dawn of the modern linguistic era, Noam Chomsky stated that the central problem for linguistic theory “is essentially the problem of constructing a theory of language acquisition” (1965, 27). Today, we know more than ever about how children acquire different languages. Two-year-old children acquiring the Mayan language K’iche’ produce transitive and intransitive inflections on verbs (Pye, 1983); two-year-old children acquiring Spanish produce verb suffixes for person and tense (Gathercole, Sebastián, and Soto, 1999); two-year-old children acquiring the Bantu language Sesotho produce passive verbs (Demuth, 1990); and two-year-old children acquiring the Inuit language Inuktitut produce polysynthetic verb complexes (Allen, 2017).

Altogether, this would appear to be a golden age of language-acquisition research, and yet we lack a framework for assembling this rich dataset into a comprehensive picture of how children acquire language. For the most part, we publish the results of language-acquisition research on one language at a time. We train our students to investigate how children acquire a single language. Our analytic techniques work best when we can isolate one or two factors such as vocabulary size or sentence length in a single language.

Comparing the course of language development in different languages forces investigators to ignore most of the differences that distinguish the languages. While English contrasts the /p/ in pit and the /b/ in bit, the Mayan language K’iche’ contrasts the /p/ in pa ‘on’ and the voiced, implosive sound /ɓ/ in ɓa ‘gopher’. (Implosive sounds are produced by breathing in air rather than by breathing out.) The differences between English and K’iche’ involve not just sounds but every aspect of the grammar, up to and including when to say “I’m sorry.” English has a double object construction (“give me the box”) that K’iche’ lacks. K’iche’ has two “antipassive” constructions that English lacks. Subjects and direct objects are obligatory in English and optional in K’iche’. A single verb complex in K’iche’, e.g., Katenwila’, requires a whole sentence for its translation in English: “I’m going to see you.”

Comparing language acquisition in different languages brings us face to face with the problem of defining a unit of comparison that is not influenced by the differences between all of the other linguistic features in languages. Languages have different numbers and types of consonants, pronouns, verb inflections, passive voices, and locative expressions. We cannot compare how children acquire pronouns in different languages if the pronouns have different sounds, mark different semantic contrasts, and have different grammatical restrictions.

In my book, The Comparative Method of Language Acquisition Research (University of Chicago Press, 2017), I make the case for borrowing the comparative method from historical linguistics. Historical linguists have been refining the comparative method for over a century and a half to understand how entire families of languages change over time (Rankin, 2003). Historical linguistic research has produced a comprehensive analysis of the world’s languages that is unequaled in other branches of linguistics. This empirical base provides the foundation for the success of the comparative method.

While the comparative method is best known for its use in reconstructing linguistic features for prehistoric stages in families of languages, key aspects of the comparative method can help researchers compare language acquisition in languages belonging to the same family. A central element of the comparative method is its restriction to languages that share a common historical ancestor. This restriction means that it is best to compare the acquisition of English with the acquisition of other Germanic languages and to compare the acquisition of K’iche’ with the acquisition of other Mayan languages. This restriction may be viewed as a major limitation of the comparative method, but it has profound implications. One implication is that comparing acquisition results for English and K’iche’ produces spurious conclusions with no empirical basis. Another way to state this implication is that theories that account for the acquisition of English do not predict the acquisition of K’iche’.

The obverse side to the common ancestor restriction of the comparative method is that it compels investigators to initiate comprehensive acquisition studies for all of the languages within a language family. This requirement leads to the idea of comparing how children acquire every aspect of English with the way that children acquire similar features in the other Germanic languages, such as Dutch, Frisian, German, and Swedish. Despite decades of acquisition research on the individual Germanic languages, we do not have detailed studies that compare acquisition across the Germanic languages.

The comparative method begins by looking for corresponding linguistic features in related languages. Languages with a common ancestor retain many traits that betray their ancestry, such as similar sounds, words, and phrases. The fundamental advantage of analyzing corresponding linguistic features is that they have corresponding contexts of use. The focus on contexts of use gives the comparative method its ability to control for a variety of extraneous factors that obscure the study of particular linguistic features. For example, we do not understand whether the sounds that children can produce limit their production of pronouns.

The acquisition of negation illustrates how the comparative method controls extraneous factors in language-acquisition research. English has two forms of syntactic negation. The form not is used in contexts of predicate negation, e.g., “It cannot wait.” The form no is used in discourse contexts as a response to questions and commands, e.g., Adult: “Do you want to go out?” Child: “No.” No is also used for term negation to negate noun phrases, e.g., “We have no bananas today.”

Children acquiring English have to learn the proper contexts for using these different forms of negation. Amazingly, children often produce no in contexts of predicate negation, e.g., Kathryn’s “no zip” (Bloom, 1970, 150). This overextension is so widespread in the acquisition of English that we might be tempted to predict that all children will extend forms for discourse negation to contexts of predicate negation. There are sporadic examples of this overextension in German, but not in Danish and Swedish (Plunkett and Strömqvist, 1992). The difference in the development of negation between Swedish and English suggests that the link between predicate negation and auxiliary verbs in English accounts for the difference between negative acquisition in English and other Germanic languages.

We cannot extend this account of Germanic negation to the acquisition of negation in Mayan languages because the contexts of use in Germanic languages do not correspond to the negation contexts in Mayan languages. English does not have a word that expresses existence that is analogous to the existential predicates in Mayan languages. The English verb to be is marked for tense, unlike the existential predicates in Mayan languages. The Mayan language Mam uses the form miti’ to express the negation of nonhuman entities in existential contexts, e.g., Miti’ jal, “There isn’t one.” Mam extends miti’ to mark the negation of predicates in the present tense but not to predicates in the future tense or to discourse contexts, which use the form mii’n (England, 1983). Children acquiring Mam occasionally substitute the existential form miti’ for mii’n in discourse contexts.

Negation illustrates the way in which contexts of use provide the key to comparing the acquisition of related languages. The forms and uses of negation in English resemble the forms and uses of negation in other Germanic languages due to their shared history, just as the forms and uses of negation in Mam resemble the forms and uses of negation in other Mayan languages (Pye, 2016). Comparing how children acquire negation in genetically related languages avoids a fruitless search for a universal developmental path for negation.

Research on the acquisition of English has become the standard for all language-acquisition research and creates a lens that distorts research on other languages. The comparative method encourages the investigation of children learning other languages by rejecting the need to tie their results to English. The accelerating loss of endangered languages requires the use of a research framework like the comparative method that promotes the investigation of under-studied languages.

The act of documenting how children acquire an endangered language can lead parents to reassess the value of their cultural heritage and form the basis for language-revitalization efforts. Documenting the acquisition of under-studied languages is the only way to meet Chomsky’s goal of constructing a theory of language acquisition.


Allen, S. E. M. “Polysynthesis in the Acquisition of Inuit Languages.” In M. Fortescue, M. Mithun, and N. Evans (eds.), Handbook of Polysynthesis, 449–472. Oxford: Oxford University Press, 2017.

Bloom, L. Language Development: Form and Function in Emerging Grammars. Cambridge, MA: MIT Press, 1970.

Chomsky, N. Aspects of a Theory of Syntax. Cambridge, MA: MIT Press, 1965.

Demuth, K. “Subject, Topic and Sesotho Passive.” Journal of Child Language 17 (1990): 67–84.

Gathercole, V. C. M., E. Sebastián, and P. Soto. “The Early Acquisition of Spanish Verbal Morphology: Across-the-Board or Piecemeal Knowledge?” International Journal of Bilingualism 2 and 3 (1999): 133–182.

Plunkett, K., and S. Strömqvist. “The Acquisition of Scandinavian Languages.” In D. I. Slobin (ed.), The Crosslinguistic Study of Language Acquisition, vol. 3, 457–56. Hillsdale, NJ: Erlbaum, 1992.

Pye, C. “Mayan Telegraphese: Intonational Determinants of Inflectional Development in Quiché Mayan.” Language 59 (1983): 583–604.

—. “Mayan Negation Cycles.” In E. van Gelderen (ed.), Cyclical Change Continued, 219–47. John Benjamins: Amsterdam. 2016.

—. The Comparative Method of Language Acquisition Research. Chicago: Chicago University Press, 2017.

Rankin, R. L. “The Comparative Method.” In B. D. Joseph and R. D. Janda (eds.), The Handbook of Historical Linguistics, 183–212. Oxford: Blackwell (2003).

Clifton Pye is an associate professor of linguistics at the University of Kansas who specializes in documenting the acquisition of indigenous languages of the Americas, with a primary focus on the acquisition of the

Mayan languages spoken in Mexico and Guatemala. His book, The Comparative Method of Language Acquisition Research (University of Chicago Press, 2017), is available now.

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