Constraints on Abstraction: Generalization Across Languages

Constraints on Abstraction: Generalization Across Languages Sara Finley (finleysr@plu.edu) Department of Psychology, Pacific Lutheran University Tacoma, WA, 98447, USA Abstract Recent research has suggested a division between lexical representations and phonological patterns; lexical items are stored with talker-specific information, while phonological patterns are represented at a separate, abstract level of representation (Finley, 2013; Smolensky & Legendre, 2006). The present paper provides further evidence for this proposal, demonstrating that learners will extend a novel phonological pattern (vowel harmony) to speakers of a novel dialect when the words are familiar, but not when the words are unfamiliar, further supporting a distinction between the representations of lexical items and the representations of phonological patterns. Keywords: statistical learning, vowel harmony, phonological representations, lexical representations. Introduction One of the major issues in the cognitive science of language is how the phonological representations that make up words are stored in the human mind. Specifically, there is a debate between whether the phonological representations that govern word formation are represented in the mind in terms of abstract, rule-governed processes, or as exemplars of specific instances, based on the phonetic forms of lexical items. While classic phonological theory has proposed highly abstract, symbolic representations for phonological patterns (Chomsky & Halle, 1968), experimental research has questioned the abstract nature of phonological processes, and suggested that phonological rules are epiphenomenal (Port & Leary, 2005). Because listeners encode highly detailed information from the individual speakers they encounter (Nygaard & Pisoni, 1998), researchers have proposed that representations of lexical items are not based on normalized or abstract representations, but based on individual, stored exemplars (Johnson, 1997). Because the generalizations that can be made about phonological restrictions for word formation (e.g., phonotactics and morphophonology) necessarily come from examination of lexical items, it is reasonable to assume that these phonological restrictions share the same constraints on representations as lexical items (i.e., fine- grained, talker-specific representations) (Pierrehumbert, 2001). However, it is also possible that language makes use of multiple levels of representation, with fine-grained exemplar-based representations at one level, and abstract representations at another, higher level (Smolensky & Legendre, 2006). One of the difficulties in distinguishing between an abstract model of phonological representations and an exemplar model of phonological representations is in teasing apart the representations of individual words and the representations of phonological patterns, since phonological patterns are instantiated through word formation. In order to tease apart the distinction between lexical representations and phonological representations, the researcher must look to how the language handles phonological patterns in novel words. While researchers have investigated questions of phonological representations using a phonological version of a wug test (Berko, 1958), these investigations typically assume an abstract, generative view of phonological representations (Becker, Ketrez, & Nevins, 2011; Becker, Nevins, & Levine, 2012; Gouskova & Becker, 2013), and therefore do not address the question of a distinction between lexical representations and phonological rules. Another approach to testing the differences between lexical items and phonological patterns is by testing how learners treat novel and familiar forms following a brief exposure to a novel language. If there is a distinction between lexical representations and abstract phonological patterns, then learners should treat familiar, known words differently than unfamiliar, unknown words. Recent research used learning to test the hypothesis that lexical representations and abstract phonological patterns are stored under distinct representations (Finley, 2013). Participants in an artificial grammar learning experiment were exposed to a novel phonological pattern (vowel harmony, where vowels in a word shared the same value of a phonological feature, back and round), and then were tested on their knowledge of that phonological pattern using both familiar words and unfamiliar, novel words. In addition, participants were tested on the same set of familiar and novel items, but these items were spoken by an unfamiliar talker of the opposite gender. Participants were able to extend the newly learned vowel harmony pattern to both novel and familiar items, for both novel and familiar talkers. In addition, the analyses tested for a ‘transfer deficit’ from familiar to novel talkers. The more speakers make use of talker-specific representations in learning, the larger the transfer deficit should be when accepting items spoken in an unfamiliar voice. There was a clear transfer deficit for familiar items, but not for novel items. This difference suggests that learners store known items in terms of talker-specific phonetic details, but make use of abstract phonological patterns when making grammaticality judgments for novel words. These abstract representations are independent of the specific talker heard during training. The ability generalize a newly learned phonological pattern to unfamiliar talkers for both familiar and novel