Two ways to listen: Do L2-dominant bilinguals perceive stop voicing according to language mode?

How listeners categorize two phones predicts the success with which they will discriminate the given phonetic distinction. In the case of bilinguals, such perceptual patterns could reveal whether the listener's two phonological systems are integrated or separate. This is of particular interest when a given contrast is realized differently in each language, as is the case with Greek and English stop-voicing distinctions. We had Greek-English early sequential bilinguals and Greek and English monolinguals (baselines) categorize, rate, and discriminate stop-voicing contrasts in each language. All communication with each group of bilinguals occurred solely in one language mode, Greek or English. The monolingual groups showed the expected native-language constraints, each perceiving their native contrast more accurately than the opposing nonnative contrast. Bilinguals' category-goodness ratings for the same physical stimuli differed, consistent with their language mode, yet their discrimination performance was unaffected by language mode and biased toward their dominant language (English). We conclude that bilinguals integrate both languages in a common phonetic space that is swayed by their long-term dominant language environment for discrimination, but that they selectively attend to language-specific phonetic information for phonologically motivated judgments (category-goodness ratings).