Perceiving simultaneity is critical in integrating visual and auditory signals that give rise to a unified perception. We examined whether background color modulates people's perception of audiovisual simultaneity. Two hypotheses were proposed and examined: (1) the red-impairment hypothesis: visual processing speed deteriorates when viewing a red background because the magnocellular system is inhibited by red light; and (2) the blue-enhancement hypothesis: the detection of both visual and auditory signals is enhanced when viewing a blue background because it stimulates the blue-light sensitive intrinsically photosensitive retinal ganglion cells (ipRGCs), which trigger a higher alert state. Participants were exposed to different backgrounds while performing an audiovisual simultaneity judgment (SJ) task: a flash and a beep were presented at pre-designated stimulus onset asynchronies (SOAs) and participants judged whether or not the two stimuli were presented simultaneously. Experiment 1 demonstrated a shift of the point of subjective simultaneity (PSS) toward the visual-leading condition in the red compared to the blue background when the flash was presented in the periphery. In Experiment 2, the stimulation of ipRGCs was specifically manipulated to test the blue-enhancement hypothesis. The results showed no support for this hypothesis, perhaps due to top-down cortical modulations. Taken together, the shift of PSS toward the visual-leading condition in the red background was attributed to impaired visual processing speed with respect to auditory processing speed, caused by the inhibition of the magnocellular system under red light.

中文翻译：

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感知视听同步性时对背景颜色的调制。

感知同时性对于整合产生统一感知的视觉和听觉信号至关重要。我们研究了背景色是否调节了人们对视听同步性的感知。提出并检验了两个假说：（1）红色受损假说：由于红色细胞抑制了巨细胞系统，因此在观看红色背景时视觉处理速度下降。（2）蓝色增强假说：在观看蓝色背景时，视觉和听觉信号的检测均得到增强，因为它刺激了对蓝光敏感的固有光敏性视网膜神经节细胞（ipRGC），从而触发了更高的警报状态。参与者在执行视听同时判断（SJ）任务时暴露于不同背景：在预先指定的刺激发作异步（SOA）上出现了闪光和蜂鸣声，参与者判断了是否同时显示了两种刺激。实验1表明，当周围出现闪光时，与蓝色背景相比，红色的主观同时性（PSS）点朝着视觉领先条件的偏移。在实验2中，对ipRGCs的刺激进行了特殊处理，以测试蓝色增强假说。结果表明没有支持这一假设，可能是由于自上而下的皮层调制。综上所述，在红色背景下，PSS向视觉领先状态的转移归因于听觉处理速度方面的视觉处理速度受损，这是由红光下的巨细胞系统的抑制引起的。