acquisition is to map those conventional terms onto appropriate conceptual categories”
(Clark, 1991, p.35).
What evidence is there that children observe conventionality ? First they target adult
words from the start. They store in their memory word-forms based on what they hear
from adults. As they are exposed to more of the input language, they must add to their
repertoires of stored forms (plus tentative meanings) since they will rely on those in
recognising words and processing further utterances from the speakers around them.
Second, children use such representations not only as targets for comprehension but also
as targets for production. When they try to produce the words they have been hearing,
they can use as guides any forms already stored in memory. The forms they store are
unlikely at first to match adult targets exactly since young children at this stage are also
working on the phonology of the language, and do not yet know which distinctions are
systematic and which are not.
Contrast predicts that children will assume that differences in form mark, differences in
meaning. From this and conventionality, it follows that in building up a vocabulary: (a)
words contrast in meaning; (b) established words have priority; (c ) unfamiliar (new)
words fill lexical gaps; (d) innovative words fill lexical gaps. These predictions essentially
parallel those made for adult language-use. The difference is that children start from a very
small vocabulary and very limited knowledge of the world. Their knowledge about
categories is necessarily limited by experience. Children have to find out which possible
contrasts, in fact, hold in their language and, at first, they will not necessarily observe the
same ones as adult speakers. They also have many more gaps in their vocabularies. They
can fill these gaps with new words that they have heard used in contrast to familiar ones.
They also fill them at times with innovative words Coinedjust for the occasion.
2.3.2.1.6 Single level constraint or Basic level constraint
With the single level constraint, children act as if all the words they produce at first apply
at only one level of specificity, as if there were only one level in the lexicon, with no
Superordinate or subordinate levels at which one could group objects lexically (Clark,
1993).
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