We suggest here a Growing Trees approach for the description of the acquisition of various syntactic structures in Hebrew, based on the main results reported in Friedmann and Reznick (
In the early stages of the acquisition of syntax, not all syntactic structures are initially available to the child, but they develop gradually. Here we propose an account for the order of acquisition of various syntactic structures. The heart of our account is that the stages of acquisition follow the geometry of the syntactic tree, along the lines of the cartographic analysis of the clause, with special reference to the left periphery (LP), as described by Rizzi (
We believe that cartographic research and the study of development can interact in fruitful ways. In one direction, cartography provides detailed maps of the fundamental zones of the syntactic tree which may bring to light patterns underlying apparently disparate developmental effects. In the other direction, developmental data may provide original evidence on the organization of complex structural maps. In this paper we illustrate this fruitful dialogue, suggesting a Growing Trees account for the order of acquisition that emerges from the findings of a study by Friedmann & Reznick (
Under the described growing trees view, young children may be using only lower portions, of various sizes, of clausal structures, without higher layers. Given a complete representation like (1) in the adult grammar, children may use only layer A, creating the treelet as in (2), or layers A and B (3), or all three layers A, B, and C (which then becomes the adult state, as in (1)). Importantly, we do not expect to have a structure in which an internal layer B is missing as in (4), where only A and C are acquired.
(1) |
(2) |
(3) |
(4) | *impossible dangling representation, missing an internal layer |
Such direction, from lower to higher layers, is consistent with standard assumptions on the bottom-up nature of syntactic computations, going from the contentive part of the clause, the lexical layer, to the functional ones, the functional spine of the clause (
This logic is akin to the logic of truncation (
The truncation and the growing tree views have in common the idea that lower layers cannot be omitted if higher ones are present. They differ, though, in one crucial respect: under truncation the higher layers of the structure are available (though not necessarily used), whereas under growing trees the higher layers of the tree are not yet available at the particular stage of development under consideration. Under truncation, higher layers could be used, given a structural requirement of the construction, whereas under growing trees, if a layer has not been acquired yet, the child would not be able to produce the construction that involves it. The two devices are not inconsistent, but the growing tree mechanism may characterize earlier stages of acquisition (see De Lisser et al., this volume, for discussion).
The logic of growing trees is also in line with the conceptualization suggested by several researchers, according to which the early tree is smaller, and the acquisition of syntax involves the acquisition of higher parts of the tree. Some of these researchers suggested that the small, early tree includes no functional nodes, only VP (
Once cartographic representations are adopted, possible truncation sites and the potential stages in the growing tree are significantly multiplied, so the important empirical question that arises is which layers are actually observed in each acquisition stage. In this paper we will focus in particular on the observed growing stages in the left periphery of the clause.
Our evidence will be grounded on data from Hebrew, so we begin (Section 1.1) with presenting the cartographic map for Hebrew (mainly its left periphery), inspired by the one developed for Romance (starting from
Intensive cartographic research over the last two decades led to a detailed map of the higher (so-called left) part of the clause along the lines given in (5) for Italian/Romance (schematic description adapted from
(5) | Force > Int > Top > Q/Foc > Mod > Fin > IP |
Assuming the inventory of functional positions in the left periphery in (5), let us now review some fundamental aspects of the rich map of the periphery of the clause in Hebrew, which will offer some guidance for the interpretation of the developmental findings.
Starting from the uppermost part of the tree, Force is the highest head in Hebrew. This can be seen in the distribution of the complementizer and embedding marker
(6)
a.
Ani
I
xoshev
think
[Force
[TopP
et
ha- glida
the-ice.cream
ha- zo
the-this
[ha- yalda
the-girl
axla.]]]
ate
‘I think that this girl ate this ice-cream.’
b.
Ha-glida
the-ice.cream.
[Force
ot-a
[ha- yalda
the-girl
axla]]]
ate
hayta
was
yeruka.
green
‘The ice-cream that the girl ate was green.’
(6’)
*Ani
I
xoshev
think
[TopP
et
ha- glida
the-ice.cream
ha- zo
the-this
[ForceP
axla.]]]
ate
The introducer of embedded yes/no questions (the interrogative marker
(7)
Ani
I
toha [IntP
wonder
im
if
[TopP
et
nisui
experiment
ha- xazara
the-repetition
ha- arox
the-long
ha- ze
the-this
[miri
Miri
herica
ran
be-acma.]]]
by-herself
‘I wonder whether Miri ran this long repetition experiment by herself.’
(7’)
*Ani
I
toha [TopP
wonder
et
nisui
experiment
ha-xazara
the-repetition
ha- arox
the-long
ha-ze [IntP
the-this
im
if
[miri
Miri
herica
ran
be-acma.]]]
by-herself
We keep Force and Int separate as in (5) because cross-linguistic evidence shows that Int can in fact be lower than the declarative Force marker (
Top, in turn, is higher than Q, the position to which the Wh element of root Wh questions moves.
(8)
(Yoni already presented the acquisition paper…)
… ve-[TopP
… and-
et
ha- maamar
the-paper
al
about
afazia, [QP
aphasia
mi
who
roce
wants
lehacig?]]
to.present
… ‘and who wants to present the-paper about aphasia?’
(8’)
*….
*
ve-[QP
and-
mi [TopP
who
et
ha- maamar
the-paper
al
about
afazia
aphasia
roce
wants
lehacig]]?
to.present?
(9)
(You presented the acquisition paper very nicely…)
….
….
ve-[IntP
and-
lama [TopP
why
et
ha- maamar
the-paper
al
about
afazia
aphasia
[at
you
lo
no
roca
want
lehacig?]]]
to.present
… ‘and why don’t you want to present the-paper about aphasia?’
The orderings Why > Top and Top > Wh in (8)–(9) clearly show, by transitivity, that
Adverbs can be preposed to the LP, and they appear to be hosted in a dedicated position, Mod(ifier), a position distinct from Top (
(10)
Pitom
suddenly
Yoni
Yoni
hitxarfen
flipped_out
ve- halax.
and-left
‘Suddenly Yoni flipped out and left.’
Mod necessarily occupies a low position in the LP, in fact lower than Q – the position occupied by Wh elements for argument Wh questions as in (8) (and some adjunct, but not
(11)
[Q
Mi [Mod
who
pitom
suddenly
kam
stood_up
ve-halax?]]
and-left
‘Who suddenly stood up and left?’
(11’)
??[Mod
Pitom [Q
suddenly
mi
who
kam
stood_up
ve-halax?]]
and-left
In Hebrew there is no overt morphological marker for the Fin head, lexicalizing the Fin position. We take the surface position of the inflected verb in inversion structures as the manifestation of Fin. Following much current literature starting from Shlonsky (
We can observe in (12) that the adverb in Mod can precede the preposed finite verb, in Fin, which precedes the subject (in the higher part of IP). This order shows that Mod is higher than Fin.
(12)
[ModP
Pitom
suddenly
[FinP
lakax
took
[IP
Yoni
Yoni
et
ha- duvdevanim
the-cherries
ve- halax.]]]
and-left
‘Suddenly Yoni took the cherries and left.’
The same point can be made about Q and Top. We can observe in (13) and (14) that the Wh element in (13) and the topic in (14) precede the preposed finite verb, in Fin, which precedes the subject. This order establishes that Q is higher than Fin and that Top is higher than Fin. (and, by transitivity, given that Int is higher than Top (7), Int is higher than Fin as well).
(13)
a.
Argument question:
Ma
what
axla
ate
ha- yalda
the-girl
b- a- kikar?
in-the-square
‘What did the girl in the square eat?’
b.
Adjunct question:
Eix
how
osa
does
para?
cow
‘What sound does a cow make?’
c.
Embedded argument question:
Ani
I
toha
wonder
ma
what
axla
ate
ha- yalda
the-girl
b- a- kikar.
in-the-square
‘I wonder what the girl ate in the square.’
(14)
Et
ha-glida
the-ice.cream
axla
ate
ha- yalda
the-girl
be-teavon
in- appetite
rav.
much
‘The girl ate the ice-cream with much appetite.’
Verb inversion is possible in Hebrew after the relative complementizer
(15)
Relative complementizer
Ha- glida
the-ice.cream
she- axla
that-ate
ha- yalda
the-girl
hayta
was
yeruka.
green
‘The ice-cream that the girl ate was green.’
(15’)
Embedding marker
*Ani
I
xoshev
think
she- axla
that-ate
ha- yalda
the-girl
glida.
ice.cream
In conclusion, Fin is the lowest head within the LP, preceded by all other left peripheral positions identified, Force, Int, Top, Q, and Mod. The above empirical observations yield the order
Map of the functional sequence of the clause in Hebrew.
It is interesting to note that the order that emerges from the distributional evidence in Hebrew is essentially the same as the one found for Romance as in the schematic representation in (5) above, as well as cross-linguistically (Japanese,
We base our account on results reported in Friedmann and Reznick (
Friedmann and Reznick examined the order of acquisition of various syntactic constructions in Hebrew, using a sentence repetition task in which 60 monolingual typically-developing Hebrew-speaking children aged 2;2–3;10 repeated 80 sentences each, and an analysis of the spontaneous speech of 61 (other) children aged 1;6–6;1 (56 who were recorded once and 5 whose longitudinal data were recorded and analysed), which included a total of 27,696 utterances.
The sentence repetition task included structures with A-movement, which were sentences with unaccusative verbs in SV order, three types of sentences derived by A-bar movement: subject relatives, object relatives, and topicalization structures, and sentences involving verb inversion in adverb-VS order with unergative and transitive verbs. The test also included SV sentences with unergative and transitive verbs, which were matched in words, length and number of words to the structures with movement, in order to control for extra-linguistic cognitive factors such as memory and attention (for more details see
Data gathered through both methodologies were analyzed using the concept of
In these examples, one capacity includes the other as a subpart, or implies the other. There is a conceptual parallelism between the growing trees logic and the Guttman scale. If we think of structure building as occurring from lower to higher layers, under the growing trees view, higher parts of the tree necessarily include lower parts, and the acquisition of the higher parts would necessarily imply the acquisition of the lower ones.
A summary of the findings from Friedmann & Reznick (
Here, too, the Guttman scale was very robust, with 6 children showing none of the structures; 7 showing simple SV with unergative and transitive verbs, and SV, as well as VS, with unaccusative verbs; 9 children who produced SV sentences as well as Wh questions; 34 who produced SV sentences, Wh questions, as well as relative clauses/topicalization/embedded clauses. (Three of these 34 children, the bottom 3 in
The results from the spontaneous speech analyses and from the repetition task yield a converging picture regarding stages of acquisition: SV structures, including those derived by A-movement with unaccusative verbs, are acquired first, then Wh questions are acquired, and then relative clauses, topicalization structures, and sentential embedding structures are acquired together.
The three stages emerge in a robust and crystal-clear manner, as shown by the fact that the relevant clusters of constructions can be neatly organized in Guttman scales. These results raise further theoretical questions, though:
Why does A-movement, illustrated by SV order with unaccusative verbs, occur before any instance of A-bar movement?
Why are Wh questions acquired about one year (with individual variation) before other A-bar structures such as relative clauses and topicalization?
Why are topicalization, relative clauses, and clausal embedding acquired at the same time?
It is hard to capture the three structures mentioned in question 3, topicalization, relative clauses, and clausal embedding, as a natural class in terms of properties like embedding and movement: two (relative clauses and sentential embedding) are embedded structures and the other is not; two (topicalization and relative clauses) involve movement, but the other does not.
Our goal in the present paper is to provide a principled basis for the analysis of the three stages, also addressing the puzzles just mentioned. The key ingredient is the cartographic representation, which offers a fine-grained hierarchical structure detailed enough to draw the required distinctions. We propose a “Growing Trees” approach by which the map of the left periphery is acquired gradually, starting from the lower layers, and then moving to higher layers.
In the next section (Section 3) we present our Growing Trees account and show how it captures the three stages emerging from Friedmann and Reznick (
At the heart of our approach to the stages of structure acquisition that emerge from both the repetition study and the analysis of the spontaneous speech corpus is the idea that the stages correspond to specific zones of functional layers in the cartographic tree. Each stage of acquisition corresponds to a larger and larger part of the tree. The lower parts of the tree are acquired first, and then higher and higher parts are gradually acquired.
We ascribe the three stages identified in Friedmann & Reznick (
Three stages of acquisition of the syntactic structure of the clausal map.
In
In
In
These stages, we believe, develop following a maturational schedule. This is consistent with the finding that age is not a good predictor of structure acquisition. Just like other biological maturational properties (teething, puberty), the stages apply to all children, but the ages in which these stages are realized greatly differ. Thus, for example, in the corpus there is an 18 months old child who is already at Stage 2, whereas another child who is 26 months old is still at Stage 1. One can say that the 18 months old child reached the maturational stage that allowed her to already project Stage 2 structures, whereas the 26 months old child was still at an earlier point in the maturational schedule.
We now discuss each of these stages in more detail, derive new predictions from the theory and examine them empirically, and then discuss a further stage of development of a different kind, which follows the completion of the acquisition of the entire clausal tree structure.
In
Stage 1 of the growing tree.
The existence of SV order with unaccusative verbs, then, provides explicit evidence for A-movement. The occurrence of this structure in our Stage 1 supports the view that A-movement is available from early stages (as claimed in
In the data of children who are at Stage 1 we see that they produce unaccusative verbs in both SV and VS orders. The data in our corpus also provide direct evidence that children distinguish between unaccusatives on the one hand and unergatives (and transitives) on the other. At this stage, only with unaccusatives do we also find the VS order, which is the order of merge according to the unaccusative hypothesis (
Another consideration is relevant here. Chomsky (
From Stage 2 on, we start seeing evidence that part of the structure of the left periphery became available (See
Stage 2 of the growing tree (also including the structures acquired in Stage 1).
At this stage, the children produced root argument Wh questions of various kinds: subject, object, PP object, object questions inquiring about the verb phrase (‘what are you doing?’), as well as adjunct
Another head that is included in the map of the lower field is Mod. If preposed adverbs move to spec-Mod, then we expect them to also appear in Stage 2, together with Wh questions. And this is precisely what our data show: of the 12 children who were at Stage 2, five indeed produced sentences with preposed adverbs (see example (16); none of the Stage 1 children did).
The acquisition of the various structures organized by stage in which the structure is acquired, and ordered by the stage in which each child has acquired it (rather than by age). Each row summarizes the production of a different child, a blue (shaded) cell indicates that the child produced this structure; a white (unshaded) cell indicates that the child did not produce any instance of this structure; a grey cell means that the corpus of this child did not include any verb of the relevant type (for example, the corpus did not include any unaccusative verb).
(16)
Axshav
now
ani
I
ekax
take.
et
ha- dag
the-fish
ha- ze. (Uri, 2;5)
the-this
‘Now I will take this fish.’
As we discussed above, acquisition data may shed light on theoretical questions. The observed properties of the acquisition of Stage 2 provides a case in which data from acquisition may inform theory, here pertaining to the derivation of yes/no questions.
In principle, three possibilities exist with respect to the representation of the yes/no feature in the syntactic tree: no feature in the LP, a feature in Q, or a feature in Int. If the language allows for yes/no questions without an overt morpho-syntactic yes/no marker, and the interrogative interpretation is uniquely expressed through a special intonation at PF, one conceivable option would be that there is no yes/no feature in the LP: the assignment of a special intonational contour could be triggered by an IP-internal featural specification. A second possibility is that the yes/no feature resides where the Wh operator resides, in Q, which is in the lower field of LP. A third option is that the yes/no feature in main questions resides where it resides in embedded yes/no questions, in Int, in the higher LP zone (
A way to inform the decision between the three options would be to examine whether yes/no questions are acquired with declarative SV sentences (which would support the no-feature-in-the-LP option), with root Wh questions (which would support the feature-in-Q option), or with embedded yes/no questions (supporting the feature-in-Int option).
In order to address this question, we conducted an analysis of the corpus used in Friedmann & Reznick (
The results, summarized in
The pattern of acquisition of root and embedded Wh and Y/N questions.
We also performed a further analysis considering the longitudinal data of two more children who were recorded bi-weekly. Here we could assess, for each child, when yes/no questions first appeared relative to the other structures. The longitudinal data yielded similar results, as shown in
A growing tree: Longitudinal data – Hagar.
A growing tree: Longitudinal data – Leor.
An additional indication for the close proximity between the appearance patterns of the two types of questions can be seen when analyzing the time of first appearance of each question type in the longitudinal data of nine children (see Appendix A). These data indicate that 3 children produced a Wh question before a yes/no question, 3 had them simultaneously, and 3 started using yes/no questions before Wh questions, all within 6 weeks.
Taken together, the 56 children’s speech samples as well as the longitudinal data indicate that yes/no questions are acquired together with Wh questions in Stage 2, both appear later than Stage 1, where children produce declarative SV sentences, and before Stage 3 where they produce embedded questions (and embedded declaratives, relatives, and topicalization)
The finding that yes/no questions appeared simultaneously with root Wh questions supports the possibility according to which the yes/no feature resides in Q, in the lower LP layer. One possible implementation would be to assume, following much literature, that a null yes/no operator is present in polar questions, the null counterpart of the overt Wh operator in Wh questions. This null operator would reside in the specifier position of the Q head, in the lower part of the LP. Once this position becomes available, it may attract a Wh operator, or host a yes/no operator.
In the next stage, Stage 3, the higher field of the left periphery becomes available (see
Stage 3, the final stage of the growing tree (also including the structures acquired in stages 1 and 2).
It is not surprising that relative clauses appear together with sentential embedding, because relative clauses are embedded clauses. A more surprising property of the natural production data of this stage is the finding that the appearance of root topicalization structures coincides with the appearance of embedded clauses, as topicalization is a typical main clause phenomenon, much as root question formation. We suggest that the co-occurrence of the three constructions is a straightforward consequence of the fact that they all involve positions in the same left peripheral area, constituting the higher field of the LP.
Let us concentrate now on embedding, starting from the most straightforward case, the embedding of selected declarative clauses. A natural assumption about selection is that the selection of finite embedded clauses is categorially uniform, with the selected property expressed in the highest position of the complementizer system. Namely, all verbs selecting a finite complement select a ForceP, in which the selection properties of different verbs are expressed:
Embedded declaratives in Hebrew are introduced by the embedding marker
As for (finite) relative clauses, they are also introduced in Hebrew by the complementizer
The cartographic structure of relative clauses in Hebrew.
The discussion of selection anchored in Force also directly pertains to embedded questions, which are selected clauses as well. Under the general theory of selection that we are assuming, the selection of embedded questions will also occur in Force. This would mean that in Force there is a question feature. Many languages provide evidence that the Wh element or the embedded yes/no question marker in fact occur in a position lower than the embedded Force head (
It is crucial to notice that Stage 3 is not only an “embedding stage”. We have already mentioned that root topicalization structures appear in Stage 3. This follows from the cartography of the CP system, in which positions hosting topics cross-linguistically appear in the higher field (see our cartographic Section 1.1 above demonstrating this order for Hebrew).
A look at the map in
This theoretical prediction led us to analyze the different types of questions in the children’s production, and to examine when
The acquisition data, summarized in
There were 17 children who produced
It is worth noticing that the cartographic analysis predicts a split between
The late acquisition of
We can now examine the data with respect to the relation between two types of preposing: adverb preposing and topicalization. In the cartographic section (Section 1.1) we saw that adverb preposing targets a dedicated position Mod, distinct from and lower than Top, which is targeted by preposed topics.
Given that Mod is lower than Q and given our stage typology, we expect Mod to be available in Stage 2 alongside Wh questions, whereas topicalization is only expected to be available in Stage 3. And indeed, the acquisition data manifest this distinction clearly: there were five children (of the 12 children in Stage 2) who produced preposed adverbs
The emerging picture of the three stages in structure acquisition is summarized in
The different stages as reflected in the corpus: Stage 1 in the table includes SV structures with unergatives and unaccusatives, SV and VS structures with unaccusatives; Stage 2 includes root Wh and yes/no questions and preposed adverbs; Stage 3 includes relative clauses, topicalization,
The results summarized in
The order of acquisition, summarized for Hagar in
A considerable body of experimental work shows that in many languages, including Hebrew, children cannot understand and produce certain object relative clauses, object topicalization structures, and object Wh questions before age 6 (
How can these seemingly contradicting data be reconciled? We propose that, in fact, there is no contradiction here, but rather a new piece added to the puzzle. In earlier work (
And indeed, a further analysis of the spontaneous speech samples points exactly in this direction: the children produced many A-bar structures, including subject and object relatives, topicalizations, and Wh questions, and from age 3;3 all of them did, but none of the relatives, topicalizations, and Wh questions in the samples included an intervention structure of the relevant type, with a lexically-restricted DP crossing another one.
Instead, all the object dependencies that the children produced were structures without intervention. The object relatives they produced included a pronominal intervening subject, in the form of an arbitrary plural null subject (example (17)), or a referential (null/overt) subject pronoun (examples (18) and (19) respectively). Children also produced free object relatives at this stage (9 of the 14 children who produced object relatives).
(17)
Object relative with arbitrary pro subject:
Ze
this
oxel
food
she-(arb pro)-notnim
that- give.
b-a-tei.
in-the-tea
‘that’s food that one puts(?) in the tea.’
(18)
Object relative with null pro subject:
Hine
here
ha- gorila
the-gorilla
she-(pro)-macat.
that- found.2
‘Here is the gorilla that you found.’
(19)
Object relative with pronoun subject:
Ani
I
ekax
take.
od
another
cura
form
she-ani
that-I
roce.
want
‘I will take another form that I want.’
For Wh questions, intervention occurs when the Wh element is of the
(20)
Eize
which
tinok
baby
(arb pro)-nasim
put.
po
here
levad?
alone
‘Which baby shall we put here alone?’
Crucially, none of the sentences with object dependencies that the participants produced included a lexically-restricted DP crossing another lexically-restricted DP.
Is it the case that children simply do not use two lexically-restricted noun phrases in the same clause, irrespective of the structure? Well, no. That this is not the case can be shown by the fact that 12 of the 20 children who produced subject relatives did so with a lexically restricted relative head and a lexically restricted object, hence with two lexically restricted DPs but not in an intervention configuration (see example (21). For a similar result in Italian see Martini et al. (
(21)
Subject relatives with two lexically restricted DPs:
Dag
fish
be-ceva
in- color
kesef
silver
she- lo
that-no
maca
found
l- o
for-him
xaverim.
friends
‘A silver-colored fish that hasn’t found any friends.’
Is it the case that children avoid lexically-restricted subjects? Again, no, in their simple SV sentences, 45 children produced lexically-restricted subjects.
The fact that we found object relative clauses, object questions, and topicalizations and no subject-object asymmetry is therefore fully consistent both with the Growing Trees approach and with the approach in terms of locality and intervention.
In fact, this points to another dimension of acquisition: acquisition is not just tree structure growing. Rather, we recognize here another developmental stage, which does not have to do with structure building but rather with the development of the ability to compute intervention configurations. The finding that children in our corpus did not spontaneously produce any intervention structure, even though they did produce so many object dependencies, lends strong support in favour of the intervention approach. It also supports the independence of this developmental dimension from structure building: the tree can be grown, and thus be able to host the relevant landing site positions of an A-bar dependency, but on top of it, the child has to be able to compute intervention locality.
Stage 1 of the stages of acquisition of the syntactic tree we presented so far involved a tree consisting of both VP and IP. An open question is whether a stage exists that precedes this Stage 1, that includes an even smaller chunk of the syntactic tree. Three hypothetically possible stages preceding Stage 1 are imaginable. Below we describe each of them and address their hypothetical defining properties.
More straightforwardly, the hypothetical non-availability of the functional structure of the clause will also have implications for inflection: under the assumption that inflectional specifications such as, in particular, agreement with the subject in Phi features, and also tense inflection on the verb, require licensing of the inflected verb by the appropriate head(s) in the inflectional field, in a hypothetical stage without functional structure, the verb would not be properly inflected.
In our data, we have not seen any of these hypothetical stages preceding Stage 1– none of the children showed the patterns expected under any of the three: we did not see a stage in which unaccusatives appeared only in VS order – there were no children who only produced unaccusatives in the VS order, without the SV order, contra possibility c) (and also, under certain assumptions of the movement of the internal argument, contra a) and b)).
Additionally, there is evidence that the agreement system is functioning, even for the children who were in the earliest stage of acquisition in our study, as we did not see children who made (number) agreement errors in SV sentences.
In conclusion, we did not see in our study any of the hypothetical stages considered in this section for a lower chunk of the tree acquired before Stage 1. This does not necessarily mean they do not exist, as it could be the case that the transition to the next stage is so short that our corpus study could not catch them (
Our research is based on a dialogue between two research domains: the study of the fine details of syntactic structures within the cartographic perspective, and the empirical study of the acquisition of syntax. We have illustrated how this dialogue can be fruitful for both trends of study. Cartography offers a detailed characterization of the hierarchically ordered sets of functional heads that constitute major zones of the clausal structure. Such finely articulated representations can offer a structural basis to understand the stage-by-stage unfolding of syntactic development. Reciprocally, the study of acquisition can offer new types of evidence to consolidate and refine cartographic results, and also to address questions that are difficult to adjudicate in purely structural terms by just looking at adults’ linguistic data.
The fundamental empirical observation on which our analysis is based is that different kinds of structures appear in a strict sequence in the acquisition of Hebrew. This sequence is obscured if one compares age-based groups, due to a large individual variation in the speed of acquisition. But it clearly emerges through the use of Guttman scales, which are particularly effective in revealing implicational relations between properties. The Growing Trees account we propose is based on the empirical results of Friedmann and Reznick (
The cartographic representation of the left periphery offers a natural structural basis to understand the stage-by-stage development of syntactic structures.
The functional structure is ordered according to a sequence of functional heads. The key hypothesis here is that the tree grows in the child’s mind in the sense that internal layers are mastered before more external ones, respecting the cartographic hierarchy. Children can produce a certain construction only when they master the relevant functional heads involved in it. As for the acquisition of various types of movement, in a probe-goal approach to movement (internal merge licensed by a probe-goal search operation), the availability of the probing head is essential for a certain type of movement to take place, so the typology of movement reduces (in part) to a structural typology. Therefore, constructions involving functional heads in higher zones and types of movement targeting the higher zones are acquired later depending on the maturational stage of the child.
Stage 1: The first stage we have identified is a stage in which VP+IP are acquired. In this stage, both External and Internal Merge are available but only IP-internal movement is attested (A-movement to subject position, straightforwardly visible with unaccusative verbs). At this stage we also observe agreement licensed by functional structure, and SV structures with unergatives and transitives (and nonfinite complements of verbs, footnote 15). No left peripheral position appears to be active in this stage, and no movements that require these positions.
Stage 2: In the second stage, the lower field of the left periphery has become available. Cartographic analysis shows that the Q position is in this lower zone (lower than the topic position, the Int position, and the landing site of relative operators). So, Wh movement to the Q position is acquired, and root questions are found in this stage, as well as root yes/no questions (which presumably involve an operator in Q). The position of Mod, another functional head in the lower LP zone, also becomes available at this stage, allowing for the production of sentences with preposed adverbs. Whereas Wh questions are found in this stage,
Stage 3: In the third stage, the structure of the higher LP becomes available, so that the whole cartographic structure of the C-system becomes accessible to the child. Selection from a higher predicate becomes possible, as the Force head is now available. Therefore, we observe full clausal subordination, so that children at this stage produce embedded declaratives, embedded Wh questions (both subject and object, as well as adjunct questions), and embedded yes/no questions, all selected by a higher predicate. Topicalization becomes available because the Top head is specified in the higher C-zone. Because the relevant landing site for relative clauses in the left periphery is now present, subject- and object relative clauses are also acquired in this stage.
Of course, the hierarchical information provided by cartographic analysis can only offer a partial guidance to the sequence of events in development, and interacts with orthogonal factors of complexity. So, for instance, in order to deal with certain intervention configurations in which the moved element and the intervener are both lexically-restricted (such as certain object relatives and certain object
Due to its grammatical nature, our account predicts that, all things being equal, the same stages documented here on the basis of production data should also hold for comprehension, since grammar is directly implicated in both. It will be interesting yet challenging to test in the future the comprehension of the different structures investigated and see whether they also form a parallel Guttman scale, and whether the stages identified in production co-occur with stages in comprehension.
Beside conforming to the cartographic order of functional heads, which we discussed above, the pattern of empirical findings emerging from the repetition test and the analysis of children’s spontaneous speech suggests novel insights into several theoretical issues concerning the shape of the syntactic tree.
We found that the acquisition of the various heads follows strict principles:
They are acquired according to their position in the cartographic tree, where higher layers are acquired after lower ones. There is no head-skipping – a higher layer (which in traditional terms would be defined by an X-bar projection of a certain head) cannot be acquired before all lower layers are acquired.
Whereas it would be imaginable that children would gradually increase their ability to hold more and more layers, head after head, this is not what we have seen. Our data crucially indicate that the functional heads are acquired in “zones” or “fields”, where several hierarchically ordered sets of functional heads are acquired together. This empirical finding supports the view that the left periphery is organized into sub-fields (see
The empirical evidence provided by acquisition identifies different stages, corresponding to different zones. The first to be acquired is the IP zone, then the LP is acquired in two steps, defining two zones: first a lower LP zone including Fin, Mod, and Q and then a higher LP zone that includes Force, Int, and Top.
In addition to providing new evidence for the split of the LP in different fields, our data provide new evidence for the major divide between an inflectional system (IP) and a left-peripheral system: our Stage 1 is characterized by the presence of the IP system, whereas the left peripheral system has not developed yet. Whereas the IP-CP distinction is quite generally assumed, the further distinction between the two LP zones suggests a novel look from acquisition to theoretical discussion: it suggests that each of the two LP zones forms some sort of relatively independent organized unit.
This opens an interesting question of what makes several layers form a zone together, and what dictates the exact point where one zone ends and the next begins. The sub-division of the LP is in fact reminiscent of attempts of identifying distinct LP fields hierarchically organized (such as a topic field vs. a focus field etc., as in e.g.,
So the search for the basis of the division into zones is still ongoing; among other things, it would also be interesting to see if such a division has a phase correlate, an issue that we leave for future research.
A further issue that the acquisition data shed some light on is the way in which main yes/no questions are expressed in the clausal structure. We showed that the acquisition data can decide between three possibilities for main yes/no questions: an operator in IP, and operator in the lower LP field (in Spec Q), or an operator in the higher LP zone, in Spec-Int. The results, indicating that root yes/no questions are acquired together with root Wh questions pointed to an operator in Q as the appropriate analysis.
Our results also directly bear on the special status of
We have shown that sentences with preposed adverbs and sentences with topicalization start occurring in different stages: adverb preposing in stage 2, and topicalization in stage 3. This follows from the different landing sites of the two constructions, respectively in the lower (Mod) and higher (Top) zone of the left periphery. This supports the refined cartographic analysis along the lines of the map in
Our study shows a fruitful dialogue between acquisition and syntactic mapping. We used cartographic insights as a detailed tool to understand the stage-by-stage unfolding of acquisition. Cartographic representations further allowed us to derive new predictions about acquisition that we then examined empirically. Reciprocally, data from development offered new evidence bearing on the cartographic organization, allowing us to adjudicate between alternative analytical hypotheses, and also raised new questions to further explore in the future.
Our new empirical analyses reported in Section 4 were performed on two types of spontaneous speech data: a corpus of 56 children, and a longitudinal database.
Our new analyses of the corpus of 56 children were done on the same corpus used in Friedmann & Reznick (
In the longitudinal data we could examine the order of acquisition of various structures for each child, by analysing the relative timeline of acquisition of the various structures between children. To examine the patterns of acquisition within a single child, we analysed the spontaneous speech of nine children who were recorded several times. In Section 4.4 we selected for the general analysis the two children for whom the database is the richest: Hagar and Leor. Hagar was recorded 114 times between the ages of 1;7–2;11, with an average of 219 utterances per sample. Leor was recorded 79 times between 1;9–3;0, with an average of 297 utterances per sample. The total number of utterances analysed for these children was 16,002.
In the analysis of yes/no questions compared to Wh questions in the longitudinal corpora we analyzed the corpora of 9 children: Hagar and Leor (described above), Lior, Naama, Smadar (the other three children reported in
Here we are dealing mainly with the functional structure above the VP and not the lower part, within the lexical layer. It would be interesting, in a future development, to find out whether a similar bottom-up order of acquisition can be detected within the lexical layer as well (which may in turn instantiate an articulated structural map, see e.g.,
We do not engage here in an empirical investigation of a potential pre-functional stage, see Section 4.6 for some relevant considerations.
The main simplification of (5) with respect to
We illustrate the position of the topic with respect to
Given that in Hebrew there is no morphosyntactic distinction between topicalization and focalization structures (they differ in interface properties: prosody and properties of information structure; see
In the initial cartographic paper (
This is in turn a particular instantiation of the fact that topics are higher than focalized phrases, and Wh and focus in main clauses are often clearly associated across languages (
The order why > Top illustrated by (9) is preferred, but the opposite order is not excluded:
(i) ? ….ve-[TopP ….and- et ha- maamar the-paper al about afazia [IntP aphasia lama why at you lo not roca want lehacig? ]] to.present
In embedded interrogatives the contrast becomes sharper, with why > Top being the only possible order:
(ii) Ani I toha [IntP wonder lama [TopP why et nisui experiment ha- xazara the-repetition ha- arox the-long ha- ze the-this [Hedva Hedva herica ran be-acma.]]] in-herself ‘I wonder why did Hedva run this long repetition experiment by herself.’
(iii) *Ani I toha [TopP wonder et nisui experiment ha- xazara the-repetition ha- arox the-long ha- ze the-this [IntP lama why [Hedva Hedva herica ran be-acma.]]] in-herself
So, the marginal acceptability of (i) may illustrate the option of an additional clause-initial topic position in main, but not in embedded clauses. That root environments may have more positions than embedded environments is not unfamiliar (see
Some other adverbs, like the temporal adverbial
(i) (b- a- yeshiva) (in-the-meeting) etmol, yesterday mi who kam stood_up ve- halax? and-left ‘(In-the-meeting) yesterday, who stood up and left?’
In contrast,
Unlike classic (Germanic) V2, in Hebrew verb movement to Fin is not obligatory. It should be noted that in Samo’s (
The distributional difference with respect to triggered inversion in
Another minimal pair illustrating the dependence on movement of V-to-Fin is provided by the contrast between topicalization structures and hanging topics (with a resumptive downstream). The first showing island sensitivity and connectivity effects, both hallmarks of movement, whereas the latter does not show such properties (and hence is analysed as a structure without movement). Verb inversion, V-to-Fin, occurs with the former, but not with the latter. As shown in the contrast between (i) and (ii), all meaning ‘Dan met this friend in the garden.’
This can be explained if Spec,Fin has to be activated by movement.
Topicalization:
(i) Et ha- xaver the-friend ha- ze the-this Dan Dan b- a- gan. in-the-garden
(i’) Et ha- xaver the-friend ha- ze the-this Dan Dan b- a- gan. in-the-garden
Hanging topic:
(ii) Ha- xaver the-friend ha- ze, the-this, Dan Dan ot- o b-a- gan. in-the-garden
(ii’) *Ha- xaver the-friend ha- ze, the-this, Dan Dan ot- o b- a- gan. in-the-garden
We thank Yuval Katz for drawing our attention to this argument.
We do not discuss further the late acquisition of I-to-C, as documented in Friedmann & Reznick (
This immediately captures the structure-preserving nature of movement (
Note that embedding of nonfinite clauses could involve a reduced structure, not involving the LP, as in the case of modals, restructuring verbs, causative verbs, etc. This type of nonfinite embedding could therefore be available already in Stage 1. We do not deal with this type of structures in the current paper. For the time being we just note that the same verb, “want”, which can take a nonfinite or a finite complement, occurs in the Hebrew corpus already at stage 1, but only with a nonfinite complement.
There are analyses according to which the relative head further moves to a nominal position outside CP– possibly to the specifier of a nominal head in between D and C (see
The acquisition of embedded questions later than root ones is consistent also with J. de Villiers’ (
The finding that topics are acquired later than (root) Wh questions converges with Tsimpli’s (
Another type of evidence for
(i) Lama why ma what kara? happened?
(ii) Lama why ma? what?
(iii) Lama why mi who met? died?
In these examples (i–iii) there is no audible pause between
See Shlonsky & Soare (
Most adverbs the children produced at this stage were “now” and “suddenly”. There were also some presentational structures beginning with
(i) Hine here safta grandma ba’a (Leor 2;2) comes ‘Here comes grandma.’
Even if
One may wonder what the children who were not yet in Stage 1 were producing. The five children in the corpus who have not yet produced SV sentences, and the two children in the longitudinal data before they produced SV sentences either produced single words (which may correspond to a pre-Merge stage of only lexical terminals), or produced in addition to single words also structures of the form want + object or imperative+object, which may correspond to a single merge stage. In the current paper we do not address the analysis of the children in these very early phases of the development of syntax.
If there is a one-word stage, which would correspond to a “terminal-only” stage, which does not include pre-syntactic devices (
To simplify the issues, here we have stated this hypothesis in terms of VP structures; if v-VP structures are systematically assumed, the options ramify further.
In both SV and VS order we have seen some gender agreement errors (10 children produced subject-verb gender agreement errors, not only children who were in Stage 1), which could be a result of the fact that the abstract gender of nouns is a lexical property that needs to be learned noun-by-noun (
Analogously, the delay of passive with respect to A-movement with unaccusatives (in languages in which both are productively present) is plausibly related to a factor independent from the structural hierarchy (possibly the “smuggling” operation required in passive but not with ordinary unaccusatives: see
Further stages are possible if other observations and considerations are taken into account. For instance, a possible further stage may be identified in which center-embedded relative clauses that is, relative clauses modifying the subject, become available as well. Whereas in Hebrew, for example, final-branching object relatives (in the intervention configuration with two lexically-restricted DPs) are acquired around age 6–7, center embedded relatives (with the relevant intervention configuration) are only mastered around age 10–11 (
We are grateful to Julia Reznick for her collaboration and contribution.
This research was supported by The Human Frontiers Science Program (RGP0057/201, Friedmann), and by the Lieselotte Adler Laboratory for Research on Child Development (Tel Aviv University, Friedmann).
The authors have no competing interests to declare.