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THE ACQUISITION OF TENSE, MODAL AND ASPECT

6.8 DISCUSSION & CONCLUSION

6.8.1 Summary of Main Findings

This work concentrated on exploring the development of the IP domain in early JC and it focused on the core TMA markers. It was found that the ability/permission modal was the first modal to be produced and used productively. The obligation, necessity, epistemic, and prediction/intention modal wi, however, were very sparse in the dataset and individual variation was significant. We saw that children rarely explore the option of overtly marking the verb for past tense and as such conclusive evidence could not be established regarding the development of the overt past tense marker. The progressive and prospective aspect markers were the first and most robust aspectual markers produced and used productively in the corpus. The omission of these markers however in contexts with aspectual meaning provides evidence of a root infinitive stage in early JC. Though TMA combinations are sporadic, whenever they co-occur within a clause, they are always consistent with the cartographic sequence of the adult system. Additionally, the distribution of the TMA markers reveals a striking correlation with the input data: progressive is most robustly attested followed by the prospective and the ability/permission modal.

137 6.8.2 Discussion

The sequence for which the various overt morphemes were attested in the IP zone and the order of productive use (based on the 2 predicate criterion) for each participant are presented in (a) and (b) respectively as follows:

91) COL:

a) Aspprogressive (1;9,28) > Aspprospective (1;11,1) > Aspcompletive and Aspretrospective (2;0,28)>

Tense (2;1,14) > Modability/permission (2;3,16) > Modwi (2;3,30) > Modobligation (2;5,14)

> Modnecessity (2;8,6)

b) Aspprogressive (1;11,1) > Aspprospective (2;0,12) > Modability/permission (2;3,30) > Modwi (2;4,15) > Tensepast (2;5,0) > Aspcompletive (2;8,6) > Aspretrospective (2;9,11)

92) ALA:

a) Aspprogressive (1;10,4) > Aspprospective (2;2,6) > Modwi (2;2,22) > Modability/permission (27;08) > Aspcompletive & Modobligation (2;4,24) > Modepestemic (2;5,23) > Aspretrospective

(2;6,12) > Modnecessity and Tense (2;6,22)

b) Aspprogressive (1;10,25) > Aspprospective (2;2,6) > Modability/permission (2;3,8) > Modwi ~ Aspcompletive (2;5,23) > Modepistemic (2;6,5) > Modobligation (2;6,12) > Aspretrospective (2;6,22) > Modnecessity (2;7,18) > Tensepast (2;11,1)

93) RJU:

a) Aspprogressive (1;11,4) > Aspprospective (1;11,15) > Modability/permission (1;11,26) > Modwi (2;3,1) > Modepestemic (2;4,4) > Aspretrospective & Tense (2;4,19) > Aspcompletive (2;5,3)

> Modnecessity (2;8,26) > Modobligation (2;11,25)

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b) Aspprogressive (1;11,4) > Aspprospective (1;11,26) > Modability/permission (2;0,30) > Modwi (2;6,18) > Aspretrospective (2;7,5) > Tensepast (2;8,12) > Aspcompletive (2;9,10) > Modobligation

~Modnecessity (3,0,25)

94) TYA:

a) Aspprogressive (2;1,5) > Aspprospective (2;5,24) > Aspcompletive (2;7,23) > Modability/permission (2;10,2) > Modnecessity (2;11,14) > Modwi (3;1,1) > Modobligation (3;1,15)

b) Aspprogressive (2;6,24) > Aspprospective (2;7,23) > Modability/permission (2;11,0) > Aspcompletive

(3;1,15)

95) KEM:

a) Aspprogressive (2;0,21) > Modability/permission (2;1,21) > Aspprospective (2;4,18) > Aspcompletive

(2;6,20) > Modwi (2;8,3) > Modepestemic (2;9,4) > Modobligation (2;9,18) > Tense (2;10,29)

> Modnecessity (3;0,10) > Aspretrospective (3;1,15)

b) Aspprogressive (2;0,21) > Aspprospective (2;6,4) > Modability/permission (2;7,5) > Modwi (2;8,19) > Aspcompletive (3;0,10) > Tensepast (3;0,24) > Modobligation (3;1,15)

96) SHU:

a) Aspprogressive & Aspprospective (2;1,23) > Modability/permission (2;3,14) > Aspcompletive &

Modobligation (2;6,04) > Modwi & Tense (2;6,20) > Aspretrospective (2;9,21) > Modnecessity

(2;11,16) >Modepestemic (3;0,0)

b) Aspprogressive (2;1,23) > Aspprospective (2;2,2) > Modability/permission (2;5,18) > Aspcompletive

~ Tensepast (2;9,5) > Aspretrospective (2;10,6) > Modwi (2;11,3) > Modnecessity (3;0,0) >

Modobligation (3;0,28)

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The overall sequence for which the various overt morphemes were first attested in the IP zone is therefore:

97) Aspprogressive (1;09) > Aspprospective (1;10) > Modability/permission (2;00) >

Aspcompletive & Aspretrospective (2;00) > Tense (2;01) > Modwi (2;02) >

Modepistemic (2;04) > Modobligation (2;04) > Modnecessity (2;06)

and the order of productive use (in keeping with the 2 predicate criterion) is:

98) Aspprogressive (1;10,25) > Aspprospective (1;11,26) > Modability/permission (2;0,30) >

Modwi (2;4,15) > Tensepast (2;5,0) > Aspcompletive (2;5,23) > Modepestemic (2;6,5)

> Modobligation (2;6,12) > Aspretrospective (2;6,22) > Modnecessity (2;7,18)

On the basis of frequency and productive use, the hypothesis that structure emerges overtime incrementally in a bottom-up manner may be too absolute and cannot account for the current findings. We see that all informants start building the aspectual zone with the following structure: Aspprogressive > Aspprospective > Modability/permission, but individual variation is evidenced thereafter.

In the target system only epistemic modals scope above Tense, while all root modals and aspectual categories scope below it. The difference in distribution between the modal types with regard to Tense is linked to the difference in semantic interpretation: modals above Tense are concerned with the speaker’s deductions or opinions while those below Tense are strictly subject-oriented properties (Cinque 1999). Examining the order of attestation of TMA in the present corpus, we see that some of the root modals and aspectual markers do not fit in the predicted categories. Of all the root modals only the Ability/Permission modal was produced before Tense was overtly realized. We see however where Modal wi was used

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productively before the productive use of Tense. In addition although all the aspectual markers examined were attested before Tense, only the Progressive and Prospective markers were used productively before the productive use of Tense. If children were building the functional hierarchy from a strict bottom-up approach, we would expect all the root modals and the aspectual markers to be attested and used productively before the productive use of Tense. The data therefore does not lend support to the ‘incremental structure building approach’ to language development. We see however that children acquiring JC never have a TMA system that contains epistemic modals (the highest element in the clausal hierarchy), but no aspectual elements (the lowest elements, located closest to the verb).

With regards to the combination of the markers, despite the scarcity in the data, one major finding was revealed. Children acquiring JC are always target-consistent with respect to the sequence of utterance. TMA elements which are located in higher clausal layers were never realized below elements which are lower in the clausal domain. This shows that children fro m an early age are aware of the rules governing the cartographic sequencing of the entire TMA zone. Such finding argues in favor of a ‘full competence’ approach to development.

It appears that the acquisition order may be also influenced by the input as the distributions of both are skewed in a similar direction. The categories of progressive aspects, prospective aspects and ability/permission modals are proportionally larger than all other TMA categories.

However the fact that children initially produce more progressive aspectual markers and less prospective aspectual markers and ability/permission modals than in the input shows that children do not exactly copy the distribution of the input, and as such the input alone cannot account for the attested order.

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In accounting for the relative order attested in the children’s development of the TMA zone, we propose that all the structure is available from the start of production in line with the full competence hypothesis. Despite the availability of structure, children nonetheless omit markers revealing a root infinitival stage in early JC. These omissions are in keeping with the full competence approach and are based on grammatical options available to the child, in line with UG. Rizzi (1993/1994) proposed that the option available to the child to ‘strip off’

external clausal layers is responsible for the attestation of root infinitives in early grammars.

Note however, that as soon as this option is no longer available to the child, around 3 years of age, children start to use the obligatory aspectual markers more productively and root infinitives decline.

An obvious question is why are some markers more productively used than others, being that all the structure is available to the child? We propose that, independent of grammatical options of truncating clausal levels, children are apparently aware that not all markers are obligatory and hence their low attestation, in line with the input data. But why is the progressive marker the first to be acquired and used productively? This we argue is due to semantic reasons. According to Brown & Bellugi (1964) children primarily communicate about the ‘here-and-now’, and as such initially acquire only the forms they need to do so.

Progressives refer to here-and-now and are used in describing ongoing activities. In keeping with Boland (2006) operators that are communicatively more relevant and are cognitively less complex are easier to acquire. The analysis of the input shows where the progressive aspect is the most dominant TMA element in the communication of young children and as such is most relevant in their early development, hence acquired first.

142 6.8.3 Conclusions

The analysis of spontaneous speech of children acquiring the TMA system in JC showed that the obligatory aspectual markers (progressive and prospective) are the first elements to be produced and productively used. These markers form the lowest level in the TMA zone, and, importantly, children do not go through a stage where the highest elements in the clausal hierarchy are produced before the lowest elements. The bottom-up structure building approach however cannot account for the fine-grained development of the TMA zone in JC as children do not necessarily acquire all aspectual markers before root modals and tense, nor will they acquire all root modals before epistemic modals. The empirical finding that children never produce target-inconsistent TMA combinations provides evidence that children acquiring JC are aware of the cartographic structure of the entire TMA domain from an early age.