The Neuroscience and Aphasia Research Unit (NARU), Division of Neuroscience and Experimental Psychology, University of Manchester, UK; School of Psychology, University of New South Wales, Sydney, NSW, Australia.
Perception in Action Research Centre & Department of Cognitive Science, Macquarie University, Sydney, NSW, Australia; ARC Centre of Excellence in Cognition and its Disorders, Australia.
Cognition. 2018 Aug;177:107-121. doi: 10.1016/j.cognition.2018.03.022. Epub 2018 Apr 13.
Individuals with grapheme-colour synaesthesia experience anomalous colours when reading achromatic text. These unusual experiences have been said to resemble 'normal' colour perception or colour imagery, but studying the nature of synaesthesia remains difficult. In the present study, we report novel evidence that synaesthetic colour impacts conscious vision in a way that is different from both colour perception and imagery. Presenting 'normal' colour prior to binocular rivalry induces a location-dependent suppressive bias reflecting local habituation. By contrast, a grapheme that evokes synaesthetic colour induces a facilitatory bias reflecting priming that is not constrained to the inducing grapheme's location. This priming does not occur in non-synaesthetes and does not result from response bias. It is sensitive to diversion of visual attention away from the grapheme, but resistant to sensory perturbation, reflecting a reliance on cognitive rather than sensory mechanisms. Whereas colour imagery in non-synaesthetes causes local priming that relies on the locus of imagined colour, imagery in synaesthetes caused global priming not dependent on the locus of imagery. These data suggest a unique psychophysical profile of high-level colour processing in synaesthetes. Our novel findings and method will be critical to testing theories of synaesthesia and visual awareness.
个体的字形-颜色联觉会在阅读非彩色文本时体验到异常的颜色。这些不寻常的体验据说类似于“正常”的颜色感知或颜色意象，但研究联觉的本质仍然很困难。在本研究中，我们报告了新的证据，表明联觉颜色以不同于颜色感知和意象的方式影响有意识的视觉。在双眼竞争之前呈现“正常”颜色会引起位置依赖的抑制性偏差，反映局部习惯化。相比之下，一个唤起联觉颜色的字形会引起促进偏向，这种偏向不受诱发字形位置的限制。这种启动不会在非联觉者中发生，也不是由于反应偏向引起的。它对视觉注意力从字形上的转移很敏感，但对感觉干扰有抵抗力，反映了对认知而不是感觉机制的依赖。而非联觉者的颜色意象会引起依赖于想象颜色位置的局部启动，而联觉者的意象会引起不依赖于意象位置的全局启动。这些数据表明联觉者的高级颜色处理具有独特的心理物理特征。我们的新发现和方法将是测试联觉和视觉意识理论的关键。
