Interleaved lexical and audiovisual information can retune phoneme boundaries

To adapt to situations in which speech perception is difficult, listeners can apply perceptual learning to adjust boundaries between phoneme categories. Such adjustment can draw on contextual, including lexical, information in surrounding speech, or on visual cues via speech- reading. In the present study, listeners proved able to flexibly adjust the boundary between two plosive/stop consonants, /p/-/t/, using both lexical and speech-reading information and given the same experimental design for both cue types. Videos of a speaker pronouncing pseudo-words, and audio recordings of Dutch words, were presented in alternating blocks of either stimulus type, and listeners were able to switch between cues to recalibrate, with effect sizes comparable to results from listeners receiving only a single source of information. Overall, audiovisual cues (i.e., the videos) produced the stronger after-effects, commensurate with their environmental applicability. Lexical cues were nonetheless able to induce retuning effects, despite fewer exposure stimuli and a changing phoneme bias, and despite a design unlike most previous studies of lexically-guided retuning and more typical of audiovisual recalibration studies. Participants who received only audiovisual exposure also showed recalibration effects comparable to previous studies, while a lexical-only group showed lower levels of retuning effects. The presence of the lexical retuning effects nonetheless suggests that lexically-based retuning may be invoked at a faster rate than previously seen. In general, this technique has further illuminated the robustness of adaptability in speech perception, and offers the potential to enable further comparisons across differing forms of perceptual learning.

为适配语音感知存在困难的场景，听者可通过感知学习（perceptual learning）调整音素类别间的边界。此类调整可依托语境信息——包括周边语音中的词汇信息——或通过唇读（speech-reading）获取的视觉线索。本研究证实，听者可灵活调整两类爆破/塞音辅音（plosive/stop consonants）/p/-/t/的边界，同时使用词汇线索与唇读线索，且两种线索的实验设计保持一致。实验中交替呈现两类刺激：说话者朗读伪词（pseudo-words）的视频，以及荷兰语词汇的音频录音；听者可在不同线索间切换以重新校准感知，其效应量与仅接收单一信息源的听者实验结果相当。总体而言，视听线索（audiovisual cues，即视频）产生的后效更强，这与其在现实环境中的适用性相符。尽管词汇线索组的暴露刺激更少、音素偏向存在动态变化，且实验设计与多数此前开展的词汇引导重调谐研究不同，更贴近视听重校准研究的典型范式，但词汇线索仍可诱发重调谐效应（retuning effects）。仅接收视听暴露的被试同样表现出与既往研究相当的重校准效应（recalibration effects），而仅词汇线索组的重调谐效应水平更低。尽管如此，词汇重调谐效应的存在表明，基于词汇的重调谐过程的触发速率可能快于此前的观测结果。总体而言，本研究进一步阐明了语音感知适应性的鲁棒性（robustness），并为不同类型感知学习间的跨范式比较提供了可行路径。