Tollin Daniel J, Yin Tom C T
Department of Physiology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
J Neurophysiol. 2003 Oct;90(4):2149-62. doi: 10.1152/jn.00381.2003. Epub 2003 Jun 11.
The precedence effect (PE) describes several spatial perceptual phenomena that occur when similar sounds are presented from two different locations and separated by a delay. The mechanisms that produce the effect are thought to be responsible for the ability to localize sounds in reverberant environments. Although the physiological bases for the PE have been studied, little is known about how these sounds are localized by species other than humans. Here we used the search coil technique to measure the eye positions of cats trained to saccade to the apparent locations of sounds. To study the PE, brief broadband stimuli were presented from two locations, with a delay between their onsets; the delayed sound meant to simulate a single reflection. Although the cats accurately localized single sources, the apparent locations of the paired sources depended on the delay. First, the cats exhibited summing localization, the perception of a "phantom" sound located between the sources, for delays < +/-400 micros for sources positioned in azimuth along the horizontal plane, but not for sources positioned in elevation along the sagittal plane. Second, consistent with localization dominance, for delays from 400 micros to about 10 ms, the cats oriented toward the leading source location only, with little influence of the lagging source, both for horizontally and vertically placed sources. Finally, the echo threshold was reached for delays >10 ms, where the cats first began to orient to the lagging source on some trials. These data reveal that cats experience the PE phenomena similarly to humans.
优先效应（PE）描述了几种空间感知现象，当相似的声音从两个不同位置发出并存在延迟间隔时就会出现这些现象。产生这种效应的机制被认为与在混响环境中定位声音的能力有关。尽管已经对优先效应的生理基础进行了研究，但对于除人类之外的其他物种如何定位这些声音却知之甚少。在这里，我们使用搜索线圈技术来测量经过训练会向声音的视在位置进行扫视的猫的眼睛位置。为了研究优先效应，从两个位置呈现短暂的宽带刺激，刺激起始之间存在延迟；延迟的声音旨在模拟单次反射。尽管猫能够准确地定位单个声源，但成对声源的视在位置取决于延迟。首先，对于沿水平面方位定位的声源，当延迟<±400微秒时，猫表现出求和定位，即感知到位于声源之间的“虚幻”声音，但对于沿矢状面高度定位的声源则没有这种现象。其次，与定位优势一致，对于400微秒到约10毫秒的延迟，无论声源是水平放置还是垂直放置，猫都仅朝着领先声源的位置定向，滞后声源的影响很小。最后，当延迟>10毫秒时达到回声阈值，此时猫在某些试验中开始首次朝着滞后声源定向。这些数据表明，猫与人类类似地经历优先效应现象。
