James S. Magnuson
Reiko A. Yamada
ATR Human Information Process. Labs., 2-2 Hikaridai, Seika-cho, Soraku-gun, Kyoto, 619-02 Japan
Experiments are described that designed to investigate how Japanese subjects develop criteria for ``R''--``L'' decisions. Subjects were asked to identify English words beginning with /r/ and /l/ in two conditions: blocked (all words produced by one talker) and mixed (words produced by several talkers). Subjects performed more accurately in the blocked condition than in the mixed condition. This indicates that, as is generally true for native-language perception, stable talker characteristics facilitate non-native speech perception. Subjects also exhibited preferences for ``R'' or ``L'' responses for some talkers in one condition, but the opposite or no preference in the other. Together, these results indicate that in the blocked condition, subjects adopted talker-specific criteria. However, when the talker changed randomly in the mixed condition, subjects were not able to adjust their criteria for each talker, but apparently based their criteria upon the range of all /r/s and /l/s they heard. Thus subjects made more responses based on the ``R'' category for some talkers, and more based on ``L'' for others. The implications for theories of perceptual normalization and non-native speech perception will be discussed.