The Adaptability of Language Specific Verb Lexicalization Biases

The Adaptability of Language Specific Verb Lexicalization Biases Catherine Havasi (havasi@mit.edu) Department of Computer Science, 77 Massachusetts Ave Cambridge MA 02139 USA Jesse Snedeker (snedeker@wjh.harvard.edu) Department of Psychology, 33 Kirkland St. Cambridge, MA 02138 USA differences in the meanings of verbs than in the meanings of nouns. To learn verbs, they argue, children must first discover how their language chooses to package events. To the extent that lexicalization patterns are systematic within a language, children should be able to draw generalizations from known instances, developing lexicalization biases which allow the pace of verb learning to accelerate. The parade case for systematic cross-linguistic variation in lexicalization is the conflation patterns that occur in verbs of motion (Talmy, 1975). A motion event consists of a thing that is moving (the figure), the location it is moving relative to (the ground), the manner in which it is moving and the path along which it moves. All languages have ways of expressing these elements, but how they do so varies. ‘Manner’ languages, such as English and Mandarin, typically pack manner of motion into the verb, leaving path for an optional prepositional phrase (“He ran into the store”). In contrast, ‘path’ languages, such as Spanish and Greek and typically encode path in the verb and fob off manner on an optional gerund (“El entro en la tienda corriendo”). In English, path verbs are relatively scarce (Gutierrez, 2001; Talmy 1975). This cross-linguistic difference in verb use shows up in distributional analyses and production studies with both children and adults (Aske, 1989; Jackendoff, 1990; Berman & Slobin, 1994). This systematic difference in lexicalization patterns also results in differences in how the speakers of manner and path languages learn new motion verbs, consistent with the predictions of Gentner’s relational relativity hypothesis (1982). When confronted with a novel verb used to describe a single motion event, English speaking adults and seven year olds will extend the word to other events with the same manner of motion but not to events that have the same path (Naigles & Terrazas, 1998; Hohenstein & Naigles, 2000). In contrast Spanish speaking adults and seven-year olds extend the verb to events that have the same path but not the same manner. Thus each group has developed a lexicalization bias that is consistent with the primary verb lexicalization pattern in their language. While verb lexicalization biases clearly exist, we know little about how they might develop or how they are mentally represented. One intriguing hypothesis comes from the literature on the development of the shape bias in noun learning. Smith and colleagues have argued that the shape bias is a generalization based on the words that the child has previously acquired (Smith, Jones, Landau, Gershkoff-Stowe & Samuelson, 2002). Children, they Abstract Languages vary in how they encode motion events. For example, English motion verbs often encode the manner of the motion while Spanish motion verbs encode the path. Efficient verb learning has been argued to involve the acquisition of language specific lexicalization biases. When given a novel verb paired with a single motion event, English speakers interpret it as a manner verb, Spanish speakers as a path verb. The present study examines the nature and plasticity of this lexicalization bias. Do lexicalization biases result in a permanent alteration of the semantic interface? Or are these biases continually shaped through our experiences with word learning? English-speaking adults were taught 12 motion verbs. The composition of the set of verbs was varied from 100% manner to 100% path with 3 levels in between. Lexicalization biases were monitored by testing verb extension after the first ambiguous exemplar of each verb. We replicate the finding that English speakers have an initial manner bias. However, we find that this bias changes over time in response to the input: Participants who learned path verbs developed a path lexicalization bias. Experiment 2 replicates this result with a different syntactic frame. Introduction Children’s early lexicons are curiously lopsided. Across a variety of linguistic environments, nouns dominate early vocabularies, while verbs are initially scarce (for a review see Gentner & Boroditsky, 2001). There are a number of explanations for initial noun dominance, which are by no means mutually exclusive. Verbs differ from nouns in the frequency with which they occur in isolation or in salient positions within the utterance and they also differ in the types of concepts that they encode and the types of entities that they pick out in the world. All of these factors have been argued to play a role in early noun dominance (Gleitman, 1990; Tardif, Shatz & Naigles, 1997; Caselli, Casadio & Bates, 1999; Snedeker & Gleitman, 2004). Gentner and her colleagues have argued that nouns are prominent in the early lexicon because they typically denote physical objects which can be individuated (and presumably conceptualized) on the basis of the child’s perceptual experience of the world (1982; Gentner & Boroditsky, 2001). Verbs, they argue are more difficult for novice language learners because perception does not package events into stable individuals. Instead languages decide how to conflate the conceptual components of events into lexical items. This results in greater cross-linguistic