The Effects of Semantic Priming on Novel Verb Inflection

The Effects of Semantic Priming on Novel Verb Inflection Molly A. McCarthy & Trina C. Kershaw mmccarthy@umassd.edu, tkershaw@umassd.edu Department of Psychology, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747 USA Abstract natural” than novel verbs with irregular past tense forms. In Experiment 3, participants produced the past tense form of a given novel verb within a sentence. Prasada and Pinker observed significantly more suffixed, or regular, past tense forms than non-suffixed, or irregular, forms. They also observed that of those novel verbs conjugated irregularly, those that were closest phonologically to their root verbs were more often conjugated irregularly. Contemporary theories of language production disagree about the cognitive mechanisms involved in the production of past tense forms of regular and irregular verbs. Two models compete to explain this process: Dual-route and Single-route. The present study tests these models using previously reported methods of production and naturalness rating of the past tense forms of novel verbs. Overall, participants show a preference for regular verb forms, both in production and rating tasks. However, presentation of a novel verb in an irregular semantic context cancels out that preference. Previous findings were not replicated, and inconclusive results show some support for both models. Single Route Models Single route models aim to eliminate the need for an abstract grammatical rule. According to these models, a connectionist network maps the stems of all verbs and their past tense forms, and makes judgments based on the intensity of the connections as to which form is produced for a given input. The same route is used to map both regular and irregular verbs to their past tense forms- hence, “single-route.” As an example, the proposed network of Rumelhart and McClelland (1987) works as a pattern-associator that learns the connections between phonological verb stems and past tense verb forms. These connections are strengthened with repetition. This is a very simplified explanation of a connectionist network, and other factors such as meaning and context also influence the connections between verbs and their past tense forms (McClelland & Patterson, 2002; Ramscar, 2002; Ramscar et al., 2012). The main criticism of single route production models is that they fail to explain what is commonly referred to as the homophone problem. This problem arises when past tense verb production is only considered in terms of phonology and grammar. There are several sets of real verbs that are homophones, but are not conjugated in the same way. For example: break/brake, and wring/ring. If a single route model is based on the connections between a phonological stem and its associated past tense form, then the difference between the past tense forms of these homophones cannot be explained. Ramscar (2002) posited that the explanation of the homophone problem lies in the meaning of verbs. He hypothesized that when given the appropriate semantic context, participants would conjugate a novel verb based on a homophone verb in the desired form. Ramscar’s results suggest that rather than being dependent on a abstract grammatical rule, past tense production is based on an inaccessible or untaught system of connections. Semantics is clearly one of the elements used in the Keywords: Past tense verb production, semantics, grammar rules The Past Tense Debate Over the past 30 years, there has been a large body of work investigating the production of past tense forms of regular versus irregular verbs (e.g. Huang & Pinker, 2010; Marcus et al., 1992; McClelland & Patterson, 2002; Pinker & Ullman, 2002; Prasada & Pinker, 1993; Ramscar, 2002; Ramscar, Dye & Hubner 2012; Rumelhart & McClelland, 1987). Currently, there are two major models competing to explain the process of inflection: dual route models (Marcus, 1992; Pinker & Ullman, 2002; Prasada & Pinker. 1993) and single route models (McClelland & Patterson, 2002; Ramscar, 2002; Ramscar et al., 2012; Rummelhart & McClelland 1987). Dual Route Models According to dual route theories, abstract grammatical rules play a central role in language processing. Dual route models propose that past tense verb production is governed primarily by a grammatical rule, which is supplemented by lexical retrieval. The grammatical rule is a suffixation rule that, simply put, tells us whenever a verb is to be put into the past tense we add the /-ed/ suffix. Lexical retrieval comes into play when an irregular past tense form has been previously learned and memorized. In cases such as these, the grammatical rule is overridden and the stored form of the verb is retrieved from the lexicon (Huang & Pinker, 2010; Pinker & Ullman, 2002; Prasada & Pinker, 1993). Strong support for dual route models can be seen in a series of experiments by Prasada and Pinker (1993). Experiments 1 and 2 demonstrated that participants rated novel verbs with regular endings as seeming “more