Does allophonic knowledge of L1 contribute to the correct discrimination of non-native sounds?

The present paper investigated the perception of four Punjabi liquids /ɾ ɽ l ɭ/ and two stops /d ɖ/ by Japanese listeners. It has been reported that Japanese listeners have difficulty in perceiving the two-way liquid contrast of English because Japanese has only one liquid phoneme. Japanese /r/ has, in fact, a rich allophonic inventory. However, no detailed perception studies have been conducted to test whether rich allophonic inventory of Japanese /r/ helps Japanese listeners to perceive the phonemic four-way liquid and two-way stop contrasts of Punjabi. Our results from the forty-eight Japanese listeners suggested that, regardless of rich allophonic inventory of /r/, the liquid-liquid contrasts are still hard to discriminate for the Japanese listeners, but liquid-stop contrasts are easy to discriminate. On the other hand, retroflex stop [ɖ], an allophone of Japanese /r/, has given some advantage in the discrimination of /d-ɖ/ contrast and some disadvantage in liquid-stop contrasts.