A useful clarification about the operation of this assumption has been made by Elbers,
van Loon-Vemoom & van Helden-Lankhaar (1993) who put forward the principle of
contrast usage. This suggests that when words are used Contrastively children not only
assume a difference between words (e.g in terms of which colour is referred to), but also
assume that the words are referring to the same dimension (e.g colour). Consequently,
Elbers, van Loon-Vervoom & van Helden-Lankhaar argue that the usefulness of contrast
is in relation to other similar words rather than to the whole of the lexicon. They also
suggest that such contrast will aid children’s understanding of the relationship between
words.
Thus, vocabulary acquisition grows naturally as the child is exposed to more and more
words and picks out the contrasts in their referents. Clark (1987) notes: “the principle of
contrast offers a powerful tool to children acquiring language. It constrains the inferences
they can make about possible meanings for new forms by distinguishing them from
already familiar forms” (p.28).
Contrast is clearly an important property of the language system and it has attracted a
number of theorists (e.g. Barrett, 1978; Markman & Hutchinson, 1984). However, a
number of criticisms have been opposed to the contrast principle. Nelson (1990) has
pointed out that not all words are used Contrastively. Also, the meaning of a word is
complex and flexible. It shifts with use rather than having a fixed meaning. Furthermore,
while constraints such as mutual exclusivity and the principle of contrast might explain
why children sometimes abandon the taxonomic and whole object constraint, they do not
explain how children actually acquire names for parts, substances, or abstract entities, let
alone how they Ieam the meanings of verbs, prepositions, determiners and so forth.
2.3.2.1.5 Contrast and Conventionality
More recently, Clark (1991) has emphasised the operation of the constraint of
conventionality as well as contrast. Conventionality is simply a pragmatic principle that
words have conventional meanings within the language community. She supposes “that
children appear to recognise very early that language is conventional, that the speakers
around them have words for objects, events, states, and relations, and that a major task in
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