Mehta Anahita H, Jacoby Nori, Yasin Ifat, Oxenham Andrew J, Shamma Shihab A
UCL Ear Institute, University College London, London WC1X 8EE, UK
Department of Psychology, University of Minnesota, Minneapolis, MN 55455, USA.
Philos Trans R Soc Lond B Biol Sci. 2017 Feb 19;372(1714). doi: 10.1098/rstb.2016.0114. Epub 2017 Jan 2.
This study investigates the neural correlates and processes underlying the ambiguous percept produced by a stimulus similar to Deutsch's 'octave illusion', in which each ear is presented with a sequence of alternating pure tones of low and high frequencies. The same sequence is presented to each ear, but in opposite phase, such that the left and right ears receive a high-low-high … and a low-high-low … pattern, respectively. Listeners generally report hearing the illusion of an alternating pattern of low and high tones, with all the low tones lateralized to one side and all the high tones lateralized to the other side. The current explanation of the illusion is that it reflects an illusory feature conjunction of pitch and perceived location. Using psychophysics and electroencephalogram measures, we test this and an alternative hypothesis involving synchronous and sequential stream segregation, and investigate potential neural correlates of the illusion. We find that the illusion of alternating tones arises from the synchronous tone pairs across ears rather than sequential tones in one ear, suggesting that the illusion involves a misattribution of time across perceptual streams, rather than a misattribution of location within a stream. The results provide new insights into the mechanisms of binaural streaming and synchronous sound segregation.This article is part of the themed issue 'Auditory and visual scene analysis'.
本研究调查了一种类似于多伊奇“八度错觉”的刺激所产生的模糊感知背后的神经关联和过程。在“八度错觉”中，每只耳朵都会听到一系列低频和高频交替出现的纯音。相同的序列呈现给每只耳朵，但相位相反，使得左耳和右耳分别接收高 - 低 - 高……和低 - 高 - 低……的模式。听众通常报告听到了高低音调交替模式的错觉，所有低音都偏向一侧，所有高音都偏向另一侧。目前对这种错觉的解释是，它反映了音高和感知位置的虚幻特征结合。我们使用心理物理学和脑电图测量方法来检验这一解释以及另一个涉及同步和顺序流分离的替代假设，并研究这种错觉潜在的神经关联。我们发现，交替音调的错觉源于双耳间的同步音对，而非单耳内的顺序音调，这表明这种错觉涉及跨感知流的时间错误归因，而非流内位置的错误归因。这些结果为双耳流和同步声音分离的机制提供了新的见解。本文是主题为“听觉和视觉场景分析”的特刊的一部分。
