when is a word not a word

Words, roughly speaking, in the psycholinguistic sense of ‘items in the mental lexicon’, consist of a phonological form coupled with semantic content. They mean something, and they have a sound structure, and these two properties can theoretically be analysed and discussed independently of each other. To give a phonological description of a particular word, for example, you would want to discuss what kind of consonants and vowels it was composed of, how many syllables, the structure of the syllables, the stress pattern, and so on; what the word actually means in the language can be treated as a separate question altogether.

You can also manipulate certain characteristics of the phonological properties of the words of a given language. You could, for example, observe that English allows the sequence “pr” at the start of words (prince, press) and “nd” at the end of words (wind, sand), and so construct the sequence “prend”. It sounds a bit like “friend”, and “pretend”, but it isn’t really related to either, and it doesn’t actually mean anything. It’s a pseudo-word, or a non-word – a phonological form which is legitimate according to the rules governing English sound sequences, but which has no meaning associated with it.

This would be just so much abstruse blether, except that non-words have been put to use in practical real-life contexts, with intriguing consequences. There exists a particular kind of language impairment in which, out of all a child’s cognitive abilities, only their language development seems to be impaired (in the absence of factors such as brain damage, hearing impairment, and so on). This is called Specific Language Impairment, or SLI. It runs in families. It has a genetic component. And geneticists have demonstrated that there is a linkage between particular regions of particular chromosomes, and particular language-related skills – most interestingly, the ability to accurately repeat lists of “nonsense words”, in tests known as nonword repetition tests.

What these tests consist of is, generally, a pre-recorded list of non-words, such as “doppelate” and “ballop”. The child hears these items played one at a time, with enough of a pause in between for them to attempt to repeat what they’ve just heard. Children with SLI not only show less accuracy in producing these items (dokkelate, toppelate, toppate might be the kind of errors you’d elicit), but performance on this kind of test is, as they say, a good marker of a heritable phenotype.

The idea behind using nonword tests was, at least originally, that it would allow us to see what the child had really mastered of the English sound system, or what his or her phonological skills were really like, once divorced from the messiness attached to their production of real words (all sorts of factors affect a child’s acquisition of real-language vocabulary, and it’s quite possible for a particular sound to be mis-pronounced in one word but produced accurately in another word). If we’re interested in “pure phonology”, then seeing how children handle phonological forms which have no semantic, pragmatic, or lexical baggage would seem to be the ideal method.

Unfortunately, large numbers of practical difficulties very quickly emerged as soon as researchers started using nonword repetition tests. One is that you need to control exactly how similar a non-word is to real words: it matters that the nonword “ballop” is really quite reminiscent of both “gallop” and “ballot”. You also need to control what combinations of sound-segments appear in your nonwords: the sequence /mf/ is legal in English (“triumph”), but much rarer than the sequence /st/, and so much harder to repeat accurately. Longer nonwords are of course more difficult to remember and repeat than shorter ones, so if your set of nonwords includes many three-syllable items with rare sound sequences and many four-syllable items which are highly reminiscent of real words, it becomes much more difficult to pin down whether a child’s poor performance is due to specifically phonological issues (such as the rarity of the sound-sequence), versus more general memory-related issues such as the number of syllables they have to remember.

This, I think, feeds into a further problem which needs to be addressed, especially in the context of trying to design new sets of nonwords which would steer clear of these early problems and allow hypotheses to be tested to distinguish between what is “phonological” and what is general “memory” (or whatever). That is the question of what, precisely, are the aspects of phonology which are of most interest to researchers investigating language impairments with a genetic component. Taking an overview of the lexicon of, say, a typically developing 7-year-old, what are the specifically phonological properties of the lexical items which we can use to test the phonological competence of language-impaired children and their family members? Or, from the other direction, what are the properties, or hypothesised properties, of the putatively phonological impairments in SLI which would allow nonwords to be designed so as to elicit, or elucidate, error patterns of theoretical importance?

In other words, for example, should a good set of nonwords rely on CVCV structures only to the extent that these exist in the two-syllable words in the lexicon? Is it useful to include presumably articulatorily complex sequences such as triconsonantal clusters, or rare consonant sequences across syllable boundaries? What is the relationship between the relative frequency of particular consonants (eg dh) and their being late-acquired?
And what exactly would a specifically phonological impairment look like? Should errors be predicted mainly in one natural class, such as fricatives (but how would you differentiate a phonological difficulty with a natural class from an articulatory or perceptual difficulty with fricative production or perception?), or mainly in syllable structure, or stress assignment? Would you predict that a nonword where all the consonants were voiceless stops would be easier or harder than one where all the consonants were nasals, and if so, why? would it be useful to have multisyllabic items with all front vowels, or all back vowels, rather than a mixture?

This matters because presumably, the usefulness of nonword repetition tests is the light which they are supposed to shed on phonology – but of course speech sounds can only be described as phonological to the extent that they mirror the properties of real words as really used in a real language. (You can’t use nonword minimal pairs to demonstrate a phonemic difference, for example: minimal pairs can only be drawn from the lexicon.) So nonwords have to reflect in some way the actual characteristics of the items in a person’s or a population’s actual lexicon. Phonology can’t exist without a lexicon, but while on the one hand nonwords that are too similar to real words undermine the rationale behind using non-words in the first place, on the other hand nonwords that are too dissimilar from the lexicon make the task into one of attempting to pronounce non-native sound sequences, rather than plausible-but-non-existent native word. Erring in either of these directions will no doubt leave us better off than with stimuli which are poorly controlled for phonological properties, but there are still plenty questions which need an answer.

Advertisements

8 thoughts on “when is a word not a word

  1. When I worked in the child language research laboratory at Purdue University, we used nonword repetition tests as part of the qualification process for studies of children with SLI. English-speaking children with SLI commonly omit grammatical morphemes such as noun plural, 3rd person singular, and possessive markers, all of which regularly take the form of /s/, /z/, or /{schwa}z/. Some of our research tasks involved measuring participants’ response to various stimuli intended to elicit marking of these morphemes, so we needed to be sure their omission was not the result of a phonological process such as final consonant deletion.

    Like

  2. Yes, this isn’t to downplay the morphosyntactic deficits at all. Various papers suggest that the nwr deficit isn’t due to articulatory difficulties either. The question is really what to make of the findings that link nonword rep performance to that particular chromosome which I can never remember the name of. There are nonwords and nonwords – if nwr indexes phonological working memory (or phon-stm), from a phonologist’s perspective you want to know what precisely is phonological, if anything, and what belongs to some other part of cognition. It was the 28-item Gathercole & Baddeley nonword rep test that was used in the linkage studies – see publications by the SLI Consortium.

    Like

  3. What to make of the link? (to Chromosome 16) The nonword test is so complicated, or the abilities needed to perform if correctly are so complex, that if you have a weakness in any part of those then you can’t do it: it’s a catch-all in that case. Lots of language disordered populations stuggle with this test of course, not just SLI – that’s why the pattern of the errors and the make-up of the test are so important.
    And there’s the Larry Shriberg short Syllable Repetition Task, it’s only got 18 nonwords, 2, 3 and 4 syllables, all with stressed vowels. He’s trying to take articulation out of the picture, or more precisely, account for the role of articulation in the performance. He’s had some success using it with childhood dyspraxia to have a look at the role of genetics in that. Let’s have a closer look.

    Like

  4. Very well said Ann (if I may say so!)

    Shriberg’s SRT is interesting not just because it makes allowances for articulation, but because it isn’t particularly phonological. Strings of stressed syllables aren’t what real English words are made of. (English sentences could consist of strings of stressed sylls – Bob bought milk eg – but not English words).

    So the real questions are in the last three paras :)

    Even sticking with stress – is there an a priori reason to think that particular stress patterns would cause more problems for SLI children than others, eg strong-weak-weak (like calendar) vs weak-weak-strong (like magazine, if that’s even end-stressed any more these days). If a nonword with a wwS stress pattern turns out to be more difficult than one with Sww, does that say something phonological (in the sense of a phonological grammar) or would it simply be an effect of the rarity or inconsistency of the wwS pattern in the ambient language?

    Like

  5. Hi Mark,

    I’m sure there are lots of uses of nonsense words. My intro section in this post is probably overdeveloped, but it was only meant to provide background to the bigger problem of the nature of the heritability of the nonword repetition deficit in families with SLI.

    Wearing my phonologist hat I’m not too clear on what you mean by syllable rules. I’d want to think of syllables as units of spoken language, which don’t map particularly transparently or enlighteningly on to conventional English orthography. So for the purposes of teaching English spelling/decoding, I’d probably be slightly sceptical about the value of teaching syllabi(fi)cation rather than, say, the identify and function of English inflectional morphemes, since most multisyllabic English words tend to be morphologically complex, and their morphological structure is probably a better guide to their spelling and pronunciation than their component syllables.

    Like

  6. Somebody just arrived here by searching for “new test of early nonword repetition”. Not sure how early is early, but we’re off to the Child Language Seminar in London in a couple of weeks, bearing a new nonword repetition test which (hopefully) controls for many of the most obvious phonological variables and is being piloted on c7yo TD children. Our abstract – https://sites.google.com/site/cathlinguistics/DickieetalabstractChildLangSeminar.pdf?attredirects=0

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s