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Article Excerpt
One internal innate constraint-based explanation for the dissociation between regular and irregular plurals in compounds arises from a theory that orders morphological processes on a hierarchy of levels (Kiparsky, 1982). According to Kiparsky's level-ordering model, morphology is generated at three hierarchical stages. At Level 1, irregular inflections and primary affixes (e.g. -ian, -ous, -ion) are applied. At Level 2, derivational affixes (e.g. -er, -ism, -ness) and nominal compounding are generated, and finally regular inflection (e.g., -ed, -s) is applied at Level 3. Morphological application proceeds through these three levels in a serial fashion such that morphology generated at a later level may not be incorporated in morphology applied at a previous stage. Because regular plurals (Level 3) are applied after nominal compounding (Level 2), regular plurals inside compounds (e.g. *rats-eater) should never occur. However, irregular plurals are applied at Level 1 before nominal compounding (Level 2), and may therefore appear in compounds (e.g. mice-eater). Thus, the level-ordering model makes the prediction that not one regular plural should ever occur within a compound (Lardiere, 1995) but irregular plurals may be optionally included.
Another explanation for the dissociation between regular and irregular plurals in compounds is that irregular plurals are represented and processed differently from regulars (Pinker, 1999; Pinker & Prince, 1988, 1992). Pinker and Prince's dual-mechanism theory proposes dissociated systems in which the processing of regular morphology is mediated by classic symbolic rules of grammar (e.g. the plural of regular English nouns is formed by attaching the inflectional morpheme [-s] to the stem [N], e.g. rat + [s] = rats). Conversely, irregulars are stored as memorized pairs of words (mouse-mice) in the mental lexicon.
In terms of how the dual-mechanism model might impact upon compounding, Marcus et al. (1995) have argued that as compounds are the product of joining together two stems from the mental lexicon to form one word, irregular plurals may be used in compounds because they are stored, already inflected, as lexical items. However, regular forms may not be included in compounds because they are products of the application of a rule that takes place outside the lexicon, 'on-line' and at a later stage than compounding in the word formation process.
Thus, as with the level-ordering model, the dual-mechanism model predicts that regular plurals should not occur in the non-head position of a compound. Irregular plurals, on the other hand, are licensed by both the dual-mechanism and the level-ordering models to appear optionally within compounds.
Table 1 presents a summary of the compound production studies carried out with native English speakers to date, including a breakdown of the percentage of regular and irregular plurals produced within compounds in these studies. It is clear from Table 1 that the omission of regular plurals from compounds is a robust experimental finding and that irregular plurals may or may not be included in compounds. Thus, these studies seem to provide support for both the dual-mechanism and the level-ordering accounts of compounding.
In some accounts of the dual-mechanism model, however, it is predicted that, in any language, all examples of regular morphology should be processed in one way and all examples of irregular morphology should be treated in another manner. Pinker and Prince (1992) state that
it is an extremely strong prediction that in any language one should find that phenomena in either of these two clusters (i.e. regular and irregular morphology) should be found exclusively in association with one another, never in association with a phenomenon from the other cluster (p. 246).
However, such a clear distinction between the two types of morphology in compounds is not apparent from the studies summarized in Table 1. In fact, the pattern of results across the studies is far from uniform. While regulars were almost always omitted from compounds, it is not true that irregulars were always included in compounds. In some studies, irregular plurals patterned with regular plurals and were omitted from compounds. Other irregulars, however, have been included in compounds.
Only in the earliest compounding study carried out by Gordon (1985) was there complete uniformity in that the 3-5-year-old children tested included 98% of regular nouns in compounds in the singular form and 98% of irregular nouns in compounds in the plural form. At the other extreme, although Lardiere and Schwartz (1997) also found that their participants included all regular nouns in their singular form, unlike Gordon's finding, their adult native English speakers also included singular irregular nouns in 95% of compounds produced. Between these two extremes, age of participants seems to be a potential determinant for whether the compounds produced included irregular plurals. It would seem from Table 1 that as native speakers mature and become more proficient in the use of their native language, they include fewer irregular plurals in compounds. For instance, Nicoladis (2000) reports that 3- and 4-year-old children include the correct irregular plural in 65% of cases in which the children were required to produce compounds using irregular nouns. The 5-6-years-olds with normally developing language ability in the study carried out by van der Lely and Christian (2000) knew the correct irregular plural in an average of 78% of cases, but they only included it in an average of 61.6% of compounds produced. The older children (6-10-year-olds) tested by van der Lely and Christian demonstrated that they knew the correct irregular plural in an average of 73% of cases but only included it in an average of 55% of compounds produced. Van der Lely and Christian's teenaged participants (aged between 14 and 17;4) were able to name all the correct irregular plurals, but they only included irregular plurals in 28.3% of compounds produced. Similarly, the 15 adult native speakers included in Murphy's (2000) study produced irregular plurals in non-head position in 28% of compounds produced. It thus appears that there may be a developmental trend to exclude irregulars as native English speakers get older.
In Gordon's (1985) level-ordering-based explanation of the compounding phenomenon, he claims that adults hardly ever produce compounds containing irregular plurals, a finding which is borne out in these experiments with adults. In fact, the lack of irregular plurals in compounds (e.g. 'toothbrush' never 'teethbrush' and 'mouse-trap' never 'mice-trap') forms the centre of Gordon's argument that an innate language process such as level ordering must mediate compound production in children. Given that adults rarely include irregular plurals within compounds, children could not learn that irregular plurals (and not regular plurals) are possible in compounds from the input to which they are exposed. Irregular plurals are licensed by the level-ordering model to appear optionally within compounds, but what Gordon fails to explain is why children 'take up the option' to include irregulars in compounds while adults do not. Similarly, the dual-mechanism model argues that irregular plurals may appear optionally within compounds; however, it fails to explain why children seem more likely to select the irregular plural from the lexicon but conversely why adults seem more likely to select the...
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