The compounding phenomena is considered to be good evidence to support the dual mechanism model of morphological processing (Pinker & Prince, 1992). However evidence from initial neural net modeling has shown that a single route associative memory based account might provide an equally, if not more valid explanation of the treatment of plurals in compounds. Further neural net modeling and empirical work is proposed to test this single route accoun

Davey, N.

Hayes, J.

Murphy, V.

Peters, L.

Smith, Pamela

English

University of Hertfordshire Research Archive

Plural Morphology in Compounding is not Good Evidence to Support theDual  Mechanism modelJenny Hayes (J.Hayes@Herts.ac.uk),Psychology Department, University of Hertfordshire, College Lane, Hatfield, AL10 9AB, United KingdomAbstractThe compounding phenomena is considered to be goodevidence to support the dual mechanism model ofmorphological processing (Pinker & Prince, 1992). Howeverevidence from initial neural net modeling has shown that asingle route associative memory based account might providean equally, if not more valid explanation of the treatment ofplurals in compounds. Further neural net modeling andempirical work is proposed to test this single route account.Key words: Psycholinguistics, compounding, neural netmodeling, connectionismIntroductionThe Compounding phenomenon Psycholinguistic researchhas shown that compound words with irregular plural nounsin non-head position (e.g. mice-eater) are produced far morefrequently than compound words with regular plural nounsin non-head position (e.g. *rats-eater) (Gordon, 1985).The Dual Mechanism Model’s Explanation ofCompounding It has been argued (Marcus, Brinkmann,Clahsen, Weise & Pinker, 1995) that the compoundingphenomenon provides good evidence for the dualmechanism model of morphological processing (Pinker &Prince, 1992). The dual mechanism model proposes thatirregular nouns and their plurals are stored as memorisedpairs of words in the mental lexicon (e.g. mouse-mice) butthat regular plurals are produced by the addition of the [–s]morpheme to the regular stem at a post lexical stage (e.g. rat+ s = rats). Compounds are created in the lexicon by joiningtwo stems together to form one word. Thus as irregularplurals are stored in the lexicon they are available to formcompound words but as only the singular stems of regularnouns are stored in the lexicon the regular plural is neveravailable to form compounds.A Single Route Associative Memory Based Explanationof Compounding An explanation of the compoundingphenomenon based on the frequency of occurrence of itemsin the linguistic input has not been considered to date.However an explanation of this sort may explain thetreatment of both regular and irregular plurals in compounds(Murphy, 2000). The hypothesis has been put forward thatchildren do not include the high type frequency regular [-s]plural morpheme in the middle of compounds because theywill always have heard it, and almost all other inflectionalmorphemes in English for that matter (Chandler, 1993), atthe end of words (van Valin, personal communication).Thus, regular plurals are excluded from compounds due toan overwhelming input pattern in which the regular pluralmorpheme [-s] never occurs in the middle of words.Conversely, irregular plurals may appear in compounds astheir usage is not guided by such a dominant input pattern.Irregular plurals have a much lower type frequency andwhile some irregulars are phonologically similar e.g. mouse-mice/ louse-lice; tooth-teeth/foot-feet/ goose-geese; man-men /woman-women there is no one dominant phonologicalpattern occurring in one particular place in the structure ofEnglish morphology.An associative memory-based account of inflectionalmorphology has been investigated by numerousconnectionist models. While the earliest connectionist modelof inflectional morphology (Rumelhart & McClelland,1986) was criticised for misrepresenting the input setavailable to children, subsequent models have successfullysimulated the putative dissociation between regular andirregular inflection for both verbal morphology (Daugherty& Seidenberg, 1994) and plural morphology (Plunkett &Juola, 1999) using a single learning mechanism and noexplicit rules.  Thus it is entirely possible that a single routeconnectionist model could also simulate the behavioraldissociation between the treatment of regular and irregularplurals in compounds. Furthermore, as well as being able tolearn mappings from input to output, connectionist modelshave also been able to learn sequential mappings (Elman1990). Thus it is envisaged that a single route associativememory system could learn that the inclusion or omission ofthe regular plural morpheme [-s] is influenced by where that[-s] morpheme occurs in a sequence of language input.Thesis Research SummaryStudy 1: The Letter [-s] as a Predictor of WordEndedness An experiment has been carried out to test anyrole that [s] (either the letter or the morpheme) might play inindicating word endedness in a stream of concatenatedletters. A neural network was trained on a concatenatedstream of 200 sentences of child directed speech taken fromthe CHILDES (Child Language Data Exchange System)corpora (MacWhinney & Snow, 1985). The study was basedon Elman (1990) who trained a simple recurrent network todiscover word boundaries from a concatenated stream ofletters. The network was required to predict the next letter itexpected to occur given the letters it had seen previously. Atthe beginning of a word the error was high but as moreletters were presented to the network the error decreaseduntil it was at its lowest at the end of the word. It washypothesised in that on a "next letter" prediction task of thiskind, a neural network would learn that after the input [-s]there was a high probability that the next input would be aword ending marker i.e. that [-s] is a good predictor of wordendedness.The network’s ability to learn that [–s] is a goodpredictor of word endedness was tested using 19 unseenwords that ended in [-s] and 19 words that ended in otherletters. The network was found to be more accurate (i.e. theerror was lower) at predicting a word ending marker after an[-s] than after all other letters combined (t = -2.08, df =18,p= 0.05). The network’s ability to learn that [-s] is a goodpredictor of word endedness was further tested bycomparing the output for 5 unseen words that ended in  [-s]with the output for 6 sets of 5 unseen words that ended ineither [-d], [-e], [-g], [-l] [-r] and [-t] respectively. Thedifference between the mean error rate for a word endingmarker after an [-s] was significantly lower than thatrecorded after [-l] (t = 5.63, df 4, p < 0.01) and [-r] (t=4.30,df 4, p = 0.01). However, while the mean error on predictinga word ending marker after [-s-] was also lower than theerror rate for a word ending marker after [-d], [-e], [-g] and[-t] this difference was not significant.As this model was intended to be a preliminaryinvestigation of how the distribution of [-s] might influenceits usage in compounds we can only draw tentativeconclusions.  However, it does seem that the presence of [-s]in the input is strongly associated with word endedness.Study 2: Nouns never follow the plural [-s] morphemeFrequency counts of child directed speech taken from theWells corpus (1981), have shown that not only does theplural [-s] morpheme never occur in the middle of words itis also never followed by another noun. Thus further neuralnetwork modeling is planned in which it is hypothesised thaton a syntactic class prediction task (Elman, 1990) that afterthe plural [-s] morpheme the error on predicting a noun willbe much higher than the error on predicting any othersyntactic class.Further Neural net modeling In subsequent modeling therole that the possessive [-‘s] morpheme may play incombination with the plural [-s] morpheme in predicting thenext syntactic class will also be investigated. Severalversions of the model are planned in which phonetic andsemantic coding will be adopted.Empirical Work Two empirical studies will also be carriedout. The first study has examined whether presentation andresponse modality affect the rate at which plurals areincluded in compounds. The second empirical study willconsider how word recognition might be impaired by thepresence of inflectional morphology in the middle of words,as this is such an infrequent pattern in English.Summary It is envisaged that it will be possible to showthat a single route associative memory system can masterthe compounding phenomena. This will be achieved bydemonstrating that the putative dissociation between regularand irregular plurals in compounds is due to learning that theregular plural [-s] morpheme is never present in the middleof a word and is never followed by a noun. If this isachieved, then an account, such as the dual mechanismmodel, which relies upon multiple forms of representationand learning mechanisms, is unwarranted.ReferencesChandler,  S. (1993). Are rules and modules necessary forexplaining language? Journal of PsycholinguisticResearch, 22,  593-606.Daugherty, K. G. & Seidenberg,  M. S. (1994). Beyond rulesand exceptions. In S. D. Lima, R. L. Corrigan  & G. K.Iverson (Eds.), The reality of linguistic rules. Amsterdam:John Benjamins.Elman, J. L. (1990). Finding structure in time. CognitiveScience, 14, 179-211.Gordon, P. (1985). Level-ordering in lexical development.Cognition, 21 , 73-93.MacWhinney, B. & Snow,  C.  E. (1985). The ChildLanguage Data Exchange System. Journal of ChildLanguage, 12, 271-296.Marcus,  G. F.,  Brinkmann,  U.,  Clahsen,  H.,  Weise, R. &Pinker, S. (1995). German inflection: The exception thatproves the rule. Cognitive Psychology,  29, 189-256.Murphy,  V.  A. (2000). Compounding and therepresentation  of  inflectional  morphology. LanguageLearning,  50,  153-197.Pinker,  S.  & Prince,  A. (1992). Regular and irregularmorphology and the psychological status of rules ofgrammar. In L. A. Sutton, C. Johnson, & R. Shields(Eds.), Proceedings of the 17th Berkeley LinguisticsSociety (pp.230-251).Plunkett,  K. & Juola,  P. (1999). A connectionist model ofEnglish past tense and plural morphology. CognitiveScience,  23,  463-490.Rumelhart D. E, & McClelland, J. L. (1986). On learningthe past tense of English verbs. In J. L. McClelland, D. E.Rumelhart and the PDP Research Group (Eds.), Paralleldistributed processing: Explorations in the microstructureof cognition, Volume 2: Psychological and biologicalmodels. Cambridge, MA: MIT Press.Wells, C. G. (1981) Learning through interaction: The studyof language development. Cambridge: CambridgeUniversity Press.

A connectionist model of English past tense and plural morphology.

Are rules and modules necessary for explaining language?

Beyond rules and exceptions. In

Compounding and the representation of inflectional morphology.

Finding structure in time.

German inflection: The exception that proves the rule.

Learning through interaction: The study of language development. Cambridge:

Level-ordering in lexical development.

On learning the past tense of English verbs. In

Regular and irregular morphology and the psychological status of rules of grammar. In

The Child Language Data Exchange System.

Plural morphology in compounding is not good evidence to support the dual mechanism model

Plural morphology in compounding is not good evidence to support the dual mechanism model

Abstract

Similar works

Full text

Available Versions

University of Hertfordshire Research Archive