Akyürek Elkan G, van Asselt E Manon
Department of Psychology, Experimental Psychology, University of Groningen, Groningen, The Netherlands.
Psychophysiology. 2015 Dec;52(12):1646-63. doi: 10.1111/psyp.12523. Epub 2015 Sep 2.
When two different color stimuli are presented in rapid succession, the resulting percept is sometimes that of a mixture of both colors, due to a perceptual process called color fusion. Although color fusion might seem to occur very early in the visual pathway, and only happens across the briefest of stimulus presentation intervals (< 50 ms), the present study showed that spatial attention can alter the fusion process. In a series of experiments, spatial cues were presented that either validly indicated the location of a pair of (different) color stimuli in successive stimulus arrays, or did not, pointing toward isoluminant gray distractors in the other visual hemifield. Increased color fusion was observed for valid cues across a range of stimulus durations, at the expense of individual color reports. By contrast, perception of repeated, same-color stimulus pairs did not change, suggesting that the enhancement was specific to fusion, not color discrimination per se. Electrophysiological measures furthermore showed that the amplitude of the N1, N2pc, and P3 components of the ERP were differentially modulated during the perception of individual and fused colors, as a function of cueing and stimulus duration. Fusion itself, collapsed across cueing conditions, was reflected uniquely in N1 amplitude. Overall, the results suggest that spatial attention enhances color fusion and decreases competition between stimuli, constituting an adaptive slowdown in service of temporal integration.
当两种不同颜色的刺激相继快速呈现时，由于一种称为颜色融合的感知过程，所产生的感知有时是两种颜色的混合。尽管颜色融合似乎在视觉通路中很早就会发生，并且只在极短的刺激呈现间隔（<50毫秒）内出现，但本研究表明空间注意力可以改变融合过程。在一系列实验中，呈现了空间线索，这些线索要么有效地指示了连续刺激阵列中一对（不同）颜色刺激的位置，要么没有，指向另一个视觉半视野中的等亮度灰色干扰物。在一系列刺激持续时间内，观察到有效线索会增加颜色融合，代价是个体颜色报告。相比之下，对重复的同色刺激对的感知没有变化，这表明这种增强是特定于融合的，而不是颜色辨别本身。此外，电生理测量表明，在个体颜色和融合颜色的感知过程中，ERP的N1、N2pc和P3成分的幅度会根据线索和刺激持续时间而受到不同的调制。在不同线索条件下，融合本身唯一地反映在N1幅度上。总体而言，结果表明空间注意力增强了颜色融合并减少了刺激之间的竞争，构成了一种为时间整合服务的适应性放缓。
