Plasticity in second language (L2) learning : perception of L2 phonemes by native Greek speakers of English

Understanding the process of language acquisition is a challenge that many researchers spanning different disciplines (e.g. linguistics, psychology, neuroscience) have grappled with for centuries. One which has in recent years attracted a lot of attention has been in the area of non-native phoneme acquisition. Speech sounds that contain multiple phonetic cues are often difficult for foreign-language learners, especially if certain cues are weighted differently in the foreign and native languages. Greek adult and child speakers of English were studied to determine which cues (duration or spectral) they were using to make discrimination and identification judgments for an English vowel contrast pair. To this end, two forms of identification and discrimination tasks were used: natural (unedited) stimuli and another ‘modified’ vowel duration stimuli which were edited so that there were no duration differences between the vowels. Results show the Greek speakers were particularly impaired when they were unable to use the duration cue as compared to the native English speakers. Similar results were also obtained in control experiments where there was no orthographic representation or where the stimuli were cross-spliced to modify the phonetic neighborhood. Further experiments used high-variability training sessions to enhance vowel perception. Following training, performance improved for both Greek adult and child groups as revealed by post training tests. However the improvements were most pronounced for the child Greek speaker group. A further study examined the effect of different orthographic cues that might affect rhyme and homophony judgment. The results of that study showed that Greek speakers were in general more affected by orthography and regularity (particularly of the vowel) in making these judgments. This would suggest that Greek speakers were more sensitive to irrelevant orthographic cues, mirroring the results in the auditory modality where they focused on irrelevant acoustic cues. The results are discussed in terms of current theories of language acquisition, with particular reference to acquisition of non-native phonemes.