Incentive to focus: Word learning helps listeners distinguish native and non-native sequences

By Lisa Davidson

Previous research in cross-language perception has shown that non-native listeners often assimilate both single phonemes and phonotactic sequences to native language categories (e.g., Best 1995, Kuhl and Iverson 1995, Dupoux et al. 1999, Flege et al. 2003). These findings suggest that it would be difficult for second language learners to overcome these phonetic barriers to learning new sounds or sequences. To study whether higher-level cues can assist learners, two experiments examined whether associating meaning with unfamiliar words assists listeners in distinguishing the phonotactically possible and unattested sequences (see also Hayes- Harb 2007 for phoneme discrimination).

In Experiment 1, American English listeners were trained on word-picture pairings of words containing a phonological contrast between CC and CəC sequences, but which were not minimal pairs (e.g., [ftake], [fətalu]). In Experiment 2, the word-picture pairings specifically consisted of minimal pairs (e.g., [ftake], [fətake]). In the test phase, listeners saw a picture and
heard words spoken by a new speaker and had to indicate which of the words matched the picture. Results showed that participants chose the accurate CC or CəC form more often when they learned minimal pairs as opposed to phonological contrast alone. Nevertheless, there was a significant asymmetry in accuracy in Experiment 1: listeners were more accurate on CəC word- picture pairings than on CC pairings. Subsequent investigation of individual listeners revealed that the participants could be divided into a high performing and a low performing group: the high performers were much more capable of learning the contrast between native and non-native words, while the low performers remained at chance. Results for high performers are shown in Figure 1 (attached).

These findings suggest that at least for high performers, learning minimal pairs provides greater incentive to distinguish non-native sequences like CC from native counterparts like CəC. These experiments can be compared to a previous AX discrimination task using the same stimuli which did not include any training on the stimuli beforehand (Davidson to appear). In the AX task, listeners were at chance in discriminating between CC and CəC tokens. Unlike evidence from the infant literature suggesting that infants may encounter processing limitations in tasks requiring them to assign meaning to contrastive sounds (Pater, Stager and Werker 2004), adults have ample resources allowing them to use meaning cues to better learn the distinction between native and non-native sequences. Furthermore, greater accuracy on phonotactically legal CəC sequences may be due to the ability to establish a more robust phonetic representation. For words learned as CC, participants seem to accept a greater variety of productions, suggesting that the native language phonological prohibition on the CC sequences used in this study hampers a detailed phonetic encoding of these items.