Language is composed of individual words. Certain words, & certain types of words, are used to construct phrases & sentences far more often than others. These words are termed CORE & are surprisingly few in number. They are employed consistently & frequently across spoken & written formats. The vast majority of words, though, are classified as FRINGE, being predominantly the naming words or nouns.
This splitting of all words (Corpus) into either CORE or FRINGE is based upon proven statistical usage. It is not a matter of conjecture. In everything we ever say, write or read we are entirely dependent on access to both CORE & FRINGE words, yet the proportionate use of one to the other is stable.
- The golden rule is that 80% of language is comprised of CORE & 20% of FRINGE words
- About 350 CORE words accounts for around 75% of the total words used (1.) (2.)
- A mere 50 words generates approximately 50% of all the words used (3.)
- The blend of CORE to FRINGE remains true across different activities & environments (4.)
- The vocabulary of CORE is consistent across all demographics of age, location, & income (4.)
The significance of this concept is huge when considering an AAC system & the respective vocabularies it contains. It is one thing for a system, whether high or low tech, to contain all the CORE, but another when it comes to efficient, easy access (cognitive & physical) to such words. Similarly, an AAC system might contain a vast number of FRINGE words but the classification & categorisation could lead to problems when it comes to locating & generating them.
So, the prime issue again comes down to navigation within the framework of an AAC system, as the user hunts for the exact words they seek to fit into a phrase or sentence. Does the configuration lessen or increase the cognitive load?
CORE vocabulary tends to be abstract or notional while FRINGE is more concrete & discrete. CORE words in particular, then, have multiple meanings, open to contextual interpretation (Semantics).
Language generation can be broken down into patterns of selection of particular parts of speech. In English this is often Subject, Verb, Qualifier or Noun. The use of verbs/adverbs; nouns/adverbs; along with the insertion of prepositions & articles is predictable, governed by rules (Syntax). Natural language depends upon placing words into patterns according to their role in sentence construction. AAC systems should mirror real language generation. Access to CORE has to be immediate & dynamic if an AAC user is going to be able to express themselves.
There is a complexity to language that has to be embraced in AAC. Young children use sophisticated language. Therefore, an AAC system has to offer the user effortless control & access to all the different verb tenses & other parts of words, like personal pronouns (Morphology).
KEY words are not CORE. They are particular to a user, who states them often, perhaps due to obsession, slang, repetition, fashion, pursuit or family. AAC must be customisable, to include them.
- Christine A. Marvin, David R. Beukelman, Denise Bilyeu AAC, Vol. 10, Dec., 1994
- Susan Balandin Teresa Iacono AAC, Volume 14, No. 3, September, 1999
- David R. Beukelman, Rebecca Jones, and M. Rowan AAC, December, 1989, Vol. 5/No. 4
- S.L.S. Stuart, D. R. Beukelman, J. King, AAC, Volume 13, No. 1, March 1997