Learning New Words: Effects of Lexical Competition and Age of Acquisition

Learning New Words: Effects of Lexical Competition and Age of Acquisition Jakke Tamminen (jjt2@york.ac.uk) M. Gareth Gaskell (mgg5@york.ac.uk) University of York, Department of Psychology York, YO10 5DD, United Kingdom (‘cathedruce’). However, directly after learning there was no sign of slowing down of base word recognition. This seemed to indicate that the novel words had not been fully lexicalized yet, despite accurate performance in the explicit recognition task. To examine whether competition effects emerged over a longer timescale, Gaskell and Dumay (2003) carried out another experiment involving two sessions separated by a week. A pause detection task (Mattys & Clark, 2002) was used to measure lexical competition, and the data indicated that no competition was evident on the first day. However, a week later participants were slower to detect the pause if the base word had a novel competitor. These results suggest that it requires some considerable time for the representations of the new words to become fully active members of the lexicon. This may be caused by a need for the new information to be integrated in memory. The word learning in Gaskell and Dumay (2003) differed from normal vocabulary acquisition in two key ways. First, the words were learned in the absence of a referent or a meaningful sentential context. Second, the effects of learning were studied only in the short term. Dumay, Gaskell and Feng (2004) addressed the first of these issues by presenting novel words in a semantic context. This did not affect the speed of lexicalization, suggesting that exposure to just the phonological form is adequate for lexicalization to take place. The current study addresses the second key difference by examining the implications of novel word learning over the following months rather than weeks. If words learned in the lab still have measurable effects on the recognition of existing words after a period of months then we can be confident that their representations are as robust as normal word representations. The existing data suggest that adults are good at learning new words, even without extended training sessions. It should thus be possible to create an artificial vocabulary to address psycholinguistic questions. Many psycholinguistic variables have been difficult to study due to confounding effects of related variables. The age of acquisition (AoA) variable has been particularly difficult to examine due to its close association with word frequency. Words acquired early in life are typically responded to more quickly than later acquired words. However, early-acquired words tend to be of high frequency, while late-acquired words tend to be of low frequency (Morrison, Chappell, & Ellis, 1997). Another challenge to AoA has been the theory of cumulative frequency (e.g. Lewis, Gerhand, & Ellis, 2001). Conventional frequency measures the number of times a Abstract Recognizing spoken words involves lexical competition. A newly learned word will engage in competition with existing words that share its onset (e.g. the novel word ‘cathedruke’ will compete with ‘cathedral’), as measured by increased recognition times to the existing word (Gaskell & Dumay, 2003). We sought to replicate this finding in a longitudinal design where the effects of lexical competition were followed up over the course of eight months. Novel words were taught at different points in time, allowing us to vary, on a small scale, the age of acquisition (AoA) of the novel items. Robust lexical representations emerged for the novel words, and remained competitors to existing words throughout the study. A dissociation in AoA effects between lexical competition and naming also emerged. Keywords: Psycholinguistics; speech; lexical competition Introduction While a great deal of research has focused on language acquisition in children, less is known about these processes in adults. One way to probe the acquisition of new words is through lexical competition, which is central to many theories of spoken word recognition. When the acoustic information of a spoken word unfolds over time, the incoming incomplete information activates matching word candidates in the listener’s mental lexicon (see e.g. Marslen- Wilson, 1993). For example, the word ‘captain’ briefly activates competitors such as ‘capsule’ and ‘captive’ before acoustic information distinguishes it from its competitors. It has also been shown that words are more difficult to recognize if they have high frequency competitors (e.g. Luce, Pisoni, & Goldinger, 1990), providing further evidence for lexical competition. Gaskell and Dumay (2003) chose real trisyllabic words with early uniqueness points (the point at which a word diverges from all its competitors), such as ‘cathedral’, as base words. A “novel word” was created for each base word by changing the ending of the base word so that the novel word diverged from it at the final vowel (‘cathedruke’). The purpose of this manipulation was to shift the uniqueness point of the base word by introducing a new competitor in the lexicon, which diverged from the base word at a late point. If ‘cathedruke’ becomes a part of the lexicon and engages in competition with ‘cathedral’, one should see a slowing in the recognition time to the base word. The results showed that direct recognition of the novel words was good. The participants were accurate in judging whether they had been exposed to ‘cathedruke’ or a foil