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Morpheme #13 of 14Brown's Stage V+29–49 months

Contractible Copula

Contractible copula 'be' is the thirteenth of Brown's 14 morphemes, mastered between 29 and 49 months in obligatory contractible contexts.

At a glance

Acquisition order
#13 of 14 (Brown 1973)
Symbol / form
's/'re (copula)
Brown's stage
V+
Typical age of mastery
29–49 months

Mastery is defined as correct use in 90% of obligatory contexts across three consecutive language samples (Brown 1973). Individual variation is wide — these ranges describe typically developing English-speaking children and should be cross-referenced against the primary literature before clinical use.

What this morpheme is

The contractible copula is the form of main-verb "be" that can be reduced to a clitic — "'s" for "is", "'re" for "are", "'m" for "am" — in the contexts where contraction is grammatically licensed. Brown identified contractible contexts as those where the copula appears in a non-final position with a host that allows the clitic ("he's tall", "they're here") and contrasted them with the uncontractible contexts where the copula must surface as a full word ("there it is"). He treated contractible and uncontractible as separate morphemes in his 14 because they reach mastery on different timelines — contractible later than uncontractible.

Acquisition trajectory

Children begin producing contractible copula sporadically in late Stage III and reach 90% mastery by approximately 49 months in typical development. The lag relative to uncontractible copula is consistent across children and is the empirical anchor for Brown's decision to split them. The first productive contracted forms appear on high-frequency hosts: "he's", "she's", "it's", "that's". The full forms ("he is", "she is") may continue to be used in parallel with the contracted forms throughout the acquisition window without signalling a problem. Brown noted that children sometimes produce a hybrid where the copula is reduced but not bound to the host ("he s tall", with a slight pause), which is a transitional form rather than an error. Children with DLD show prolonged omission of contractible copula and rarely produce the contracted form spontaneously.

Examples in obligatory context

These are the kinds of child utterances a clinician would code as a correct production of 's/'re (copula) when scoring a language sample.

  • “He's tall.”
  • “She's happy.”
  • “It's raining.”
  • “That's mine.”
  • “They're here.”
  • “I'm hungry.”

Common errors during the acquisition window

  • Omission of the copula entirely: "he tall" for "he's tall"
  • Use of the full form when the contracted form is expected in casual speech (this is not an error per se)
  • Substitution of a different verb: "he be tall" for "he's tall"
  • Inconsistent marking across hosts in the same sample

Many of these errors are developmentally normal during the acquisition window. The clinical signal is persistence past the typical age of mastery, not the presence of any single error in early production.

Clinical relevance and scoring

Contractible copula is moderately sensitive to DLD but less so than its uncontractible counterpart, because contraction allows the morpheme to "hide" phonologically and ambiguous omission is harder to score reliably. A clear case of omission — "he tall" with no audible contraction at all — is the relevant clinical signal. Score contractible copula by identifying every obligatory clausal context where the main verb is "be" linking a subject to a predicate adjective, predicate nominal, or locative phrase, and the surface form would license contraction. Code each instance as correct (full or contracted form), omitted, or substituted. Pair the score with the uncontractible copula score for a complete picture of copula development.

“Contracted forms hide. Score contractible copula by listening for the absence of "'s" rather than the presence of "is", and the diagnostic signal sharpens.”
Score the absence, not the presence

Free tools for scoring this morpheme

MLU Calculator

Paste a language sample and get Mean Length of Utterance in morphemes and words, total utterances, total morphemes, and the matching Brown's stage. Implements Brown (1973) morpheme counting rules and runs entirely in your browser.

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Brown's Stages Lookup

Interactive reference for Brown's (1973) five stages of grammatical development. Look up a stage by child age or MLU, see the MLU range, acquired morphemes, example utterances, and clinical milestones for each stage.

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DSS Calculator

Free Developmental Sentence Scoring (DSS) calculator for speech-language pathologists. Paste 50 sentences, tap weighted points across the eight Lee (1974) grammatical categories — Indefinite Pronouns, Personal Pronouns, Main Verbs, Secondary Verbs, Negatives, Conjunctions, Interrogative Reversals, Wh-Questions — plus the all-correct sentence point, and the calculator returns the live DSS with a per-category breakdown. Mobile-friendly tap-through grid, client-side, no sign-up.

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Related morphemes

#7 · Stage III

Uncontractible Copula

Uncontractible copula 'be' is the seventh of Brown's 14 morphemes, mastered between 27 and 39 months in obligatory non-contractible contexts.

#12 · Stage V

Uncontractible Auxiliary

Uncontractible auxiliary 'be' is the twelfth of Brown's 14 morphemes, mastered between 29 and 48 months in obligatory non-contractible contexts.

#14 · Stage V+

Contractible Auxiliary

Contractible auxiliary 'be' is the fourteenth and last of Brown's 14 morphemes, mastered between 30 and 50 months and the last to reach criterion.

References

  1. Brown, R. (1973). A First Language: The Early Stages. Harvard University Press, pp. 367–388.
  2. Cleave, P. L., & Rice, M. L. (1997). An examination of the morpheme BE in children with specific language impairment: The role of contractibility and grammatical form class. JSLHR, 40(3), 480–492.
  3. Pavelko, S. L., & Owens, R. E. (2017). Sampling Utterances and Grammatical Analysis Revised (SUGAR). LSHSS, 48(3), 197–215.