Scharinger Mathias, Monahan Philip J, Idsardi William J
Department of Language and Literature, Max Planck Institute for Empirical Aesthetics, Frankfurt, Germany; Department of Linguistics, University of Maryland, College Park, MD, USA; Biological incl. Cognitive Psychology, Institute for Psychology, University of Leipzig, Germany.
Centre for French and Linguistics, University of Toronto Scarborough, Canada; Department of Linguistics, University of Toronto, Canada.
Neuroimage. 2016 Mar;128:293-301. doi: 10.1016/j.neuroimage.2016.01.003. Epub 2016 Jan 11.
While previous research has established that language-specific knowledge influences early auditory processing, it is still controversial as to what aspects of speech sound representations determine early speech perception. Here, we propose that early processing primarily depends on information propagated top-down from abstractly represented speech sound categories. In particular, we assume that mid-vowels (as in 'bet') exert less top-down effects than the high-vowels (as in 'bit') because of their less specific (default) tongue height position as compared to either high- or low-vowels (as in 'bat'). We tested this assumption in a magnetoencephalography (MEG) study where we contrasted mid- and high-vowels, as well as the low- and high-vowels in a passive oddball paradigm. Overall, significant differences between deviants and standards indexed reliable mismatch negativity (MMN) responses between 200 and 300ms post-stimulus onset. MMN amplitudes differed in the mid/high-vowel contrasts and were significantly reduced when a mid-vowel standard was followed by a high-vowel deviant, extending previous findings. Furthermore, mid-vowel standards showed reduced oscillatory power in the pre-stimulus beta-frequency band (18-26Hz), compared to high-vowel standards. We take this as converging evidence for linguistic category structure to exert top-down influences on auditory processing. The findings are interpreted within the linguistic model of underspecification and the neuropsychological predictive coding framework.
虽然先前的研究已经证实特定语言知识会影响早期听觉处理，但关于语音表征的哪些方面决定早期语音感知仍存在争议。在此，我们提出早期处理主要依赖于从抽象表征的语音类别自上而下传播的信息。具体而言，我们假设中元音（如“bet”中的音）比高元音（如“bit”中的音）施加的自上而下的影响更小，因为与高元音或低元音（如“bat”中的音）相比，中元音的舌位高度不那么具体（默认）。我们在一项脑磁图（MEG）研究中检验了这一假设，在该研究中，我们在被动奇偶数范式中对比了中元音和高元音，以及低元音和高元音。总体而言，偏差刺激与标准刺激之间的显著差异表明在刺激开始后200至300毫秒之间存在可靠的失配负波（MMN）反应。中/高元音对比中的MMN振幅有所不同，当中元音标准刺激后跟随高元音偏差刺激时，MMN振幅显著降低，这扩展了先前的研究结果。此外，与高元音标准刺激相比，中元音标准刺激在刺激前的β频段（18 - 26Hz）显示出振荡功率降低。我们将此视为语言类别结构对听觉处理施加自上而下影响的趋同证据。这些发现是在语言欠规范模型和神经心理学预测编码框架内进行解释的。
