Mice Trap: A New Explanation for Irregular Plurals in Noun-Noun Compunds

Mice Trap: A New Explanation for Irregular Plurals in Noun-Noun Compounds Carolyn J. Buck-Gengler (Carolyn.Buck-Gengler@Colorado.edu) Department of Psychology and Institute of Cognitive Science University of Colorado at Boulder Boulder, Colorado 80309-0345 USA Lise Menn (Lise.Menn@Colorado.edu) Department of Linguistics and Institute of Cognitive Science University of Colorado at Boulder Boulder, Colorado 80309-0295 USA Alice F. Healy (Alice.Healy@Colorado.edu) Department of Psychology and Institute of Cognitive Science University of Colorado at Boulder Boulder, Colorado 80309-0345 USA Abstract In an experiment eliciting noun-noun compounds, participants were more likely to produce plural nouns in the first position (e.g., mice trap) when presented with an irregular plural in the stimulus (e.g., a trap for catching mice is a _____) than when presented with stimuli containing regular plurals (e.g., a trap for catching rats is a _____). When they did produce a normatively correct singular (e.g., mouse trap) in response to a stimulus with an irregular plural, response time was longer than it was for producing a singular response to stimuli containing singulars or regular plurals. This finding suggests a priming-based processing problem in producing the singulars of irregular plurals in this paradigm. Such a problem is likely also to be present in young children, which would explain their production of forms like mice trap (Gordon, 1985; Pinker, 1994) without requiring recourse to the hypothesis that they have innate grammatical knowledge. Introduction It has been observed that irregular nouns and verbs often behave quite differently than their regular counterparts. A case in point is noun-noun compound formation in English. Pinker (e.g., 1994, pp. 146-147) and others have pointed out that in general, the first noun of a noun-noun compound must be singular, but that plurals of irregular nouns seem to be more acceptable in that position. For instance, one would not say *rats catcher or *toys box, even when talking about more than one rat or toy. However, mice catcher is far more acceptable. The typical explanation given is that this follows from the theory of Level Ordering of morphology (Kaisse & Shaw, 1985; Kiparsky, 1982, 1983). In this theory, production of compounds (or at least, novel compounds) proceeds at several “levels. ” At Level 1, a base form (for almost all English nouns, the singular) or another memorized form (such as the irregular plural) is retrieved from the mental lexicon; at Level 2, compounds are formed; at Level 3, after compound formation, regular affixes such as the regular plural are added. If this production schema is taken to represent a sequence of real-time processes or a fixed mode operation of a mental grammar, the normative English pattern dispreferring *rats trap is explained by saying that the regular plural rats is created too late (at Level 3) to be placed inside a compound (at Level 2). However, irregular plurals, being retrieved from memory at Level 1, are easily incorporated during compound formation. This theory, in its general form, successfully schematized a wide variety of data in English and other languages, although by now it has been shown to have serious limitations (Bauer, 1990; Fabb, 1988). Gordon (1985) explored compound formation with children aged 3-5, and induced them to produce compounds containing plurals when presented with irregular nouns, but only singulars when primed with regular nouns. He took this result as support for the idea that level ordering in grammar must be innate, because, as he demonstrated, children are rarely exposed to irregular plurals inside compounds, so they cannot induce the rule permitting irregular plurals inside compounds from their input. However, there is another way to formulate the English pattern: English compounds obey the (soft) constraint that the first element is singular, regardless of whether the semantics has stimulated the retrieval of a plural referent (e.g., toys, cookies). Thus, if a compound such as cookie jar is called for, the retrieved cookies must be made singular before proceeding. Young children have plenty of examples of this pattern in their early years (e.g., toy box, raisin box, jelly bean jar) and could well have adduced such a rule by age 3. Using this second way of constructing compounds, we suggest a processing difficulty explanation for the experimentally observed behavior: It is harder to produce a singular when primed by an irregular plural (e.g., to produce mouse after just having heard or read mice) than it is to