Non-finite Root Forms in Children's Language Acquisition

1. GRS LX 700Language Acquisition andLinguistic Theory Week 3. Further notes onnon-finite root forms

2. Where we are • There is evidence that children around the age of 2: • Allow nonfinite verbs in main clauses—in non-NS languages. • Differentiate between the syntax of finite and nonfinite verb forms. • Show evidence from word order of functional structure above the VP. • Subject case and do-support suggest that TP/AgrP can be missing from the child representations.

3. Proposals concerning TP/AgrP • Wexler (1998): Unique Checking Constraint. • For adults, subjects need to check a feature both on T and on Agr. For kids, only one is possible (so either T or Agr must be left out, or UCC must be violated). • Predicts: NS/OI. Other reflexes, perhaps object shift in Korean. • Rizzi (1993/4): Truncation. • Adults know that CP=root. Kids don’t, so they will sometimes stop early. • Predicts: If TP is missing, so is CP. • Legendre et al. (2000): Like UCC, within OT.

4. Rizzi and truncated trees • Rizzi (1993/4): Kids lack the CP=root axiom. • The result (of not having CP=root) is that kids are allowed to have truncated structures—trees that look like adult trees with the tops chopped off. • Importantly: The kids don’t just leave stuff out—they just stop the tree “early.” So, if the kid leaves out a functional projection, s/he leaves out all higher XPs as well.

5. Truncation: < TP < CP • If kid selects anything lower than TP as the root, the result is a root infinitive—which can be as big as any kind of XP below TP in the structure. • Note in particular, though, it can’t be a CP. • So: we expect that evidence of CP will correlate with finite verbs.

6. Truncation: TP < AgrSP • Pierce (1989) looking at French observed that there are almost no root infinitives with subject clitics—this is predicted if these clitics are instances of subject agreement in AgrS; if there is no TP, there can be no AgrSP.

7. Truncation: TP <> NegP? • There is some dispute in the syntax literature as to whether the position of NegP (the projection responsible for the negative morpheme) is higher or lower than TP in the tree. • If NegP is higher than TP, we would expect not to find negative root infinitives. • But we do find negative RIs—(Pierce 1989): in the acquisition of French, negation follows finite verbs and precedes nonfinite verbs (that is—French kids know the movement properties of finiteness, and thus they have the concept of finiteness). • So, is TP higher than NegP? • Hard to say conclusively from the existing French data because there are not many negative root infinitives—but further study could lead to a theoretical result of this sort about the adult languages.

8. S O Vfin? • Usually (Poeppel & Wexler 1993) German kids put finite verbs in second position, and leave nonfinite verbs at the end. • Occasionally one finds a finite verb at the end. • Rizzi suggests we could look at this as an instance of a kid choosing AgrSP as root, where CP is necessary to trigger V2.

9. *Truncation?: Where train go? • Truncation predicts: If TP is missing, then CP should be missing. • But Bromberg & Wexler (1995) observe that bare verbs do appear in wh-questions in child English. Wh-questions implicate CP, bare verbs implicate something missing (TP or AgrP). So, truncation can’t be right. • Guasti notes that although the logic here works, English is weird in this respect: pretty much all other languages do accord with the prediction.

10. Schütze & Wexler propose a model of this in which the case errors are a result of being able to either omit AgrSP or Tense. For a subject to be in nominative case, AgrSP must be there (TP’s presence is irrelevant). For a finite verb, both TP and AgrSP must be there. English inflection (3sg present –s) relies on both. If one or the other is missing, we’ll see an infinitive (i.e. bare stem). Thus, predicted: finite (AgrSP+TP) verbs show Nom (AgrSP), but only half of the nonfinite verbs (not both AgrSP and TP) show Nom (AgrSP). We should not see finite+Acc. “ATOM”

11. Implementing the UCC • The basic idea: In adult clauses, the subject needs to move both to SpecTP and (then) to SpecAgrP. • This needs to happen because T “needs” something in its specifier (≈EPP) and so does Agr. • The subject DP can “solve the problem” for both T and for Agr—for an adult.

12. Implementing ATOM • Implementation: For adults: • T needs a D feature. • Agr needs a D feature. • The subject, happily, has a D feature. • The subject moves to SpecTP, takes care of T’s need for a D feature (the subject “checks” the D feature on T). The T feature loses its need for a D feature, but the subject still has its D feature (the subject is still a DP). • The subject moves on, to take care of Agr.

13. Implementing ATOM • Implementation: For kids: • Everything is the same except that the subject can only solve one problem before quitting. It “loses” its D feature after helping out either T or Agr. • Kids are constrained by the Unique Checking Constraint that says subjects (or their D features) can only “check” another feature once. • So the kids are in a bind.

14. Implementing ATOM • Kids in a pickle: The only options open to the kids are: • Leave out TP (keep AgrP, the subject can solve Agr’s problem alone). Result: nonfinite verb, nom case. • Leave out AgrP (keep TP, the subject can solve T’s problem alone). Result: nonfinite verb, default case. • Violate the UCC (let the subject do both things anyway). Result: finite verb, nom case. • No matter which way you slice it, the kids have to do something “wrong”. At that point, they choose randomly (but cf. Legendre et al.)

15. Minimalist terminology • Features come in two relevant kinds: interpretable and uninterpretable. • Either kind of feature can be involved in a “checking”—only interpretable features survive. • The game is to have no uninterpretable features left at the end. • “T needs a D” means “T has an uninterpretable [D] feature” and the subject (with its normally interpretable [D] feature) comes along and the two features “check”, the interpretable one survives. UCC=D uninterpretable on subjects?

16. Are kids really UG-constrained? • So, aren’t TP and AgrSP required by UG? Doesn’t this mean kids don’t have UG-compliant trees? • Actually, perhaps no. UG requires that all features be checked, but it isn’t clear that there is a UG principle that requires a TP and an AgrP in every clause.

17. Are kids really UG-constrained? • Perhaps what requires TP and AgrP are principles of (pragmatic) interpretation… • You need TP so that your sentence is “anchored” in the discourse. • You need AgrSP … why? Well, perhaps something parallel…? Wexler doesn’t really say… • Regardless, kids can check all the uninterpretable features even without TP or AgrSP; hence, they can still be considered to be UG-constrained.

18. NS/OI via UCC • An old idea about NS languages is that they arise in languages where Infl is “rich” enough to identify the subject. • Maybe in NS languages, AgrS does not need a D (it may in some sense be nouny enough to say that it is, or already has, D). • If AgrS does not need a D, the subject is free to check off T’s D-feature and be done.

19. Is there any way to see the effects of UCC even in NS languages? • Italian: Mary has laughed. • Suppose that auxiliaries (like have) also have a D-feature to be checked as the subject (in the adult language) passes through. • Not crazy:(All) the students (all) have (all) left. • UCC-constrained kids will have to drop something (the auxiliary or T), even in Italian. • Lyons (1997) reports that a “substantial proportion of auxiliaries are omitted in OI-age Italian.” • Ok, maybe. Consistent, anyway.

20. One open question… • The UCC says you can only use a D-feature on a DP to check against a functional category once. • This explains why sometimes TP is omitted (keeping AgrSP) and sometimes AgrSP is omitted (keeping TP). • but if GEN infin. comes from omitting both TP and AgrSP, what could ever cause that (particularly given Minimize Violations)?

21. Theories of missing structure • No functional projections. (Radford) Kids don’t have any functional projections (TP, CP, and so forth). This comes later. No TP, no tense distinction. • Structure building.(Vainikka, Guilfoyle & Noonan) Kids start with no functional projections and gradually increase their functional structure.

22. Theories of missing structure • “ATOM” (Full competence). (Wexler, …) Kids have access to all of the functional structure and have a very specific problem with tense and agreement that sometimes causes them to leave one out. • Truncation. (Rizzi) Like structure building but without the time course—kids have access to all of the functional structure but they don’t realize that sentences need to be CP’s, so they sometimes stop early.

23. Legendre et al. (2000) • Wexler: During OI stage, kids sometimes omit T, and sometimes omit Agr. Based on a choice of which to violate, the requirement to have T, to have Agr, to have only one. • (cf. “Kids in a pickle” slide) • Legendre et al.: Looking at development (of French), it appears that the choice of what to omit is systematic; we propose a system to account for (predict) the proportion of the time kids omit T, Agr, both, neither, in progressive stages of development.

24. Optimality Theory • Legendre et al. (2000) is set in the Optimality Theory framework (often seen in phonology, less often seen applied to syntax). • “Grammar is a system of ranked and violable constraints”

25. Optimality Theory • In our analysis, one constraint is Parse-T, which says that tense must be realized in a clause. A structure without tense (where TP has been omitted, say) will violate this constraint. • Another constraint is *F (“Don’t have a functional category”). A structure with TP will violate this constraint.

26. Optimality Theory • Parse-T and *F are in conflict—it is impossible to satisfy both at the same time. • When constraints conflict, the choice made (on a language-particular basis) of which constraint is considered to be “more important” (more highly ranked) determines which constraint is satisfied and which must be violated.

27. Optimality Theory • So if *F >> Parse-T, TP will be omitted. • and if Parse-T >> *F, TP will be included.

28. Optimality Theory • Grammar involves constraints on the representations (e.g., SS, LF, PF, or perhaps a combined representation). • The constraints exist in all languages. • Where languages differ is in how important each constraint is with respect to each other constraint.

29. Optimality Theory: big picture • Universal Grammar is the constraints that languages must obey. • Languages differ only in how those constraints are ranked relative to one another. (So, “parameter” = “ranking”) • The kid’s job is to re-rank constraints until they match the order which generated the input that s/he hears.

30. Legendre et al. (2000) • Proposes a system to predict the proportions of the time kids choose the different options among: • Omit TP • Omit AgrSP • Omit both TP and AgrSP • Include both TP and AgrSP (violating UCC)

31. French v. English • English: T+Agr is pronounced like • /s/ if we have features [3, sg, present] • /ed/ if we have the feature [past] • /Ø/ otherwise • French: T+Agr is pronounced like: • danser NRF • a dansé (3sg) past • je danse 1sg (present) • j’ai dansé 1sg past

32. The idea • Kids are subject to conflicting constraints: • Parse-T Include a projection for tense • Parse-Agr Include a project for agreement • *F Don’t complicate your tree with functional projections • *F2 Don’t complicate your tree so much as to have two functional projections.

33. The idea • Sometimes Parse-T beats out *F, and then there’s a TP. Or Parse-Agr beats out *F, and then there’s an AgrP. Or both Parse-T and Parse-Agr beat out *F2, and so there’s both a TP and an AgrP. • But what does sometimes mean?

34. Floating constraints • The innovation in Legendre et al. (2000) that gets us off the ground is the idea that as kids re-rank constraints, the position of the constraint in the hierarchy can get somewhat fuzzy, such that two positions can overlap. *F Parse-T

35. Floating constraints *F Parse-T • When the kid evaluates a form in the constraint system, the position of Parse-T is fixed somewhere in the range—and winds up sometimes outranking, and sometimes outranked by, *F.

36. Floating constraints *F Parse-T • (Under certain assumptions) this predicts that we would see TP in the structure 50% of the time, and see structures without TP the other 50% of the time.

37. French kid data • Looked at 3 French kids from CHILDES • Broke development into stages based on a modified MLU-type measure based on how long most of their utterances were (2 words, more than 2 words) and how many of the utterances contain verbs. • Looked at tense and agreement in each of the three stages represented in the data.

38. French kid data • Kids start out using 3sg agreement and present tense for practically everything (correct or not). • We took this to be a “default” • (No agreement? Pronounce it as 3sg. No tense? pronounce it as present. Neither? Pronounce it as an infinitive.).

39. French kid data • This means if a kid uses 3sg or present tense, we can’t tell if they are really using 3sg (they might be) or if they are not using agreement at all and just pronouncing the default. • So, we looked at non-present tense forms and non-3sg forms only to avoid the question of the defaults.

40. French kids data • We found that tense and agreement develop differently—specifically, in the first stage we looked at, kids were using tense fine, but then in the next stage, they got worse as the agreement improved. • Middle stage: looks likecompetition between Tand Agr for a single node.

41. A detail about counting • We counted non-3sg and non-present verbs. • In order to see how close kids’ utterances were to adult’s utterances, we need to know how often adults use non-3sg and non-present, and then see how close the kids are to matching that level. • So, adults use non-present tense around 31% of the time—so when a kid uses 31% non-present tense, we take that to be “100% success” • In the last stage we looked at, kids were basically right at the “100% success” level for both tense and agreement.

42. Proportion of non-present and non-3sg verbs

43. Proportion of non-finite root forms

44. A model to predict the percentages • Stage 3b (first stage) • no agreement • about 1/3 NRFs, 2/3 tensed forms *F2 *FParseTParseA

45. A model to predict the percentages • Stage 4b (second stage) • non-3sg agreement and non-present tense each about 15% (=about 40% agreeing, 50% tensed) • about 20% NRFs *F2 *FParseT ParseA

46. A model to predict the percentages • Stage 4c (third stage) • everything appears to have tense and agreement (adult-like levels) *F2 *FParseT ParseA

47. Predicted vs. observed—tense

48. Predicted vs. observed—agr’t

49. Predicted vs. observed—NRFs

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