Training Japanese Listeners to Identify English /r/ and /l/: II. The Role of Phonetic Environment and Talker Variability in Learning New Perceptual Categories

Author: Scott E. Lively, John S. Logan and David B. Pisoni

Abstract:
Two experiments were carried out to extend Logan, Lively and Pisoni's (1991) recent study on training Japanese Listeners to identify English /r/ and /l/. Subjects in Experiment 1 were trained in an identification task with multiple talkers who produced the /r/-/l/ contrast in initial singleton, initial consonant clusters, and intervocalic positions. Moderate increases in accuracy and decreases in response latency were observed from the pretest to the posttest and during training. Subjects also generalized to new words produced by a familiar talker and novel tokens produced by an unfamiliar voice. In Experiments 2, a new group of subjects was trained with a single talker who produced /r/-/l/ contrast in a wider variety of phonetic environments. Although subjects improved during training and showed increases in pretest-posttest performance, they failed to generalize to tokens produced by a new talker. The results of the present experiments suggest that talker variability is an important aspect of robust category formation. During training, listeners develop talker-specific, context-dependent representations for new phonetic categories by selectively shifting attention toward the contrastive dimensions of the nonnative phonetic categories. Phonotactic constraints in the native language, similarity of the new contrast to distinctions in the native language, and the distinctiveness of contrastive cues all appear to mediate the difficulty of category acquisition.