Lexically guided perceptual learning is robust to task-based changes in listening strategy

Abstract

Listeners use lexical information to resolve ambiguity in the speech signal, resulting in the restructuring of speech sound categories. Recent findings suggest that lexically guided perceptual learning is attenuated when listeners use a perception-focused listening strategy (that directs attention towards surface variation) compared to when listeners use a comprehension-focused listening strategy (that directs attention towards higher-level linguistic information). However, previous investigations used the word position of the ambiguity to manipulate listening strategy, raising the possibility that attenuated learning reflected decreased strength of lexical recruitment instead of a perception-oriented listening strategy. The current work tests this hypothesis. Listeners completed an exposure phase followed by a test phase. During exposure, listeners heard an ambiguous fricative embedded in word-medial lexical contexts that supported realization of the ambiguity as /∫/. At test, listeners categorized members of an /ɑsi/-/ɑ∫i/ continuum. Listening strategy was manipulated via exposure task (experiment 1) and explicit acknowledgement of the ambiguity (experiment 2). Compared to control participants, listeners who were exposed to the ambiguity showed more /∫/ responses at the test; critically, the magnitude of learning did not differ across listening strategy conditions. These results suggest that given sufficient lexical context, lexically guided perceptual learning is robust to task-based changes in listening strategy.

FIG. 1.

(Color online) Results for experiment 1. Panel (A) shows mean proportion correct responses during exposure for each of the exposure conditions; panel (B) shows mean reaction time (RT, in ms) to correct responses during exposure. Panel (C) shows mean proportion ASHI responses during test as a function of percent /∫/ energy in the test continuum for each exposure condition and the control condition. In panels (A) and (B), the violin length indicates the response range across participants. The violin width shows a kernel density estimation to illustrate the distribution of responses across participants; wider regions indicate greater density of participant performance. Error bars indicate standard error of the mean.

FIG. 2.

(Color online) Results for experiment 2. Panel (A) shows mean proportion correct responses during exposure for each of the exposure conditions; panel (B) shows mean reaction time (RT, in ms) to correct responses during exposure. The “eLexical” label refers to participants who were explicitly told of the speaker's ambiguous /∫/ productions. Panel (C) shows mean proportion ASHI responses during test as a function of percent /∫/ energy in the test continuum for each exposure condition and the control condition. In panels (A) and (B), the violin length indicates the response range across participants. The violin width shows a kernel density estimation to illustrate the distribution of responses across participants; wider regions indicate greater density of participant performance. Error bars indicate standard error of the mean.