Lunghi Claudia, Alais David
1] Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy [2] Institute of Neuroscience, CNR - Pisa, Via Moruzzi 1, 56124 Pisa, Italy.
School of Psychology, Brennan MacCallum Building, University of Sydney 2006, New South Wales, Australia.
Sci Rep. 2015 Mar 23;5:9413. doi: 10.1038/srep09413.
Presenting different images to each eye triggers 'binocular rivalry' in which one image is visible and the other suppressed, with the visible image alternating every second or so. We previously showed that binocular rivalry between cross-oriented gratings is altered when the fingertip explores a grooved stimulus aligned with one of the rivaling gratings: the matching visual grating's dominance duration was lengthened and its suppression duration shortened. In a more robust test, we here measure visual contrast sensitivity during rivalry dominance and suppression, with and without exploration of the grooved surface, to determine if rivalry suppression strength is modulated by touch. We find that a visual grating undergoes 45% less suppression when observers touch an aligned grating, compared to a cross-oriented one. Touching an aligned grating also improved visual detection thresholds for the 'invisible' suppressed grating by 2.4 dB, relative to a vision-only condition. These results show that congruent haptic stimulation prevents a visual stimulus from becoming deeply suppressed in binocular rivalry. Moreover, because congruent touch acted on the phenomenally invisible grating, this visuo-haptic interaction must precede awareness and likely occurs early in visual processing.
给每只眼睛呈现不同的图像会引发“双眼竞争”，即一个图像可见而另一个被抑制，可见图像每隔一秒左右交替出现。我们之前表明，当指尖探索与其中一个竞争光栅对齐的带槽刺激时，交叉取向光栅之间的双眼竞争会发生改变：匹配的视觉光栅的主导持续时间延长，其抑制持续时间缩短。在一个更严格的测试中，我们在此测量竞争主导和抑制期间的视觉对比度敏感度，无论是否探索带槽表面，以确定竞争抑制强度是否受触觉调节。我们发现，与交叉取向的光栅相比，当观察者触摸对齐的光栅时，视觉光栅的抑制减少45%。相对于仅视觉条件，触摸对齐的光栅还将“不可见”抑制光栅的视觉检测阈值提高了2.4 dB。这些结果表明，一致的触觉刺激可防止视觉刺激在双眼竞争中被深度抑制。此外，由于一致的触摸作用于现象上不可见的光栅，这种视觉-触觉相互作用必须先于意识发生，并且可能在视觉处理的早期阶段就出现。
