As a first step to investigating third language acquisition, I investigated acquisition of different accents of a second language (L2). I investigated whether subjects could acquire L2 phonemes in two different L2 accents, even though they had only been trained how to discriminate L2 phonemes in one of the L2 accents. Such tests help to understand if learners can extend their knowledge of L2 phonemes to third+ languages. 

The test focused on English liquid consonant acquisition by native Japanese speakers. Liquid consonants in English have different varieties depending on accent: varying from (post) alveolar approximant or retroflex (e.g. American English) ~ tap or flap (e.g. Scottish English). We first taught American English varieties of liquid consonants /l/ and /r/ to the native Japanese speakers, focusing on the articulation of /r/ which is an approximant produced with lip rounding. After five weeks training, they became able to discriminate American English /l/ and /r/. However, when we then tested their liquid discrimination ability of Scottish accent (Scottish tap is different from American English /r/), we found that their discrimination of Scottish English /l/ and /r/ was not very good. Therefore, training with American accent did not improve their discrimination ability of a different (Scottish tap) accent.