Contrast affects the strength of synesthetic colors
Contrast affects the strength of synesthetic colors
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DOI：
10.1016/s0010-9452(08)70343-5
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发表时间：
2006-02-01
期刊：
影响因子：
3.6
通讯作者：
Ramachandran, Vilayanur S.
中科院分区：
文献类型：
--
作者：
Hubbard, Edward M.;Manohar, Sanjay;Ramachandran, Vilayanur S.
图形颜色联觉是一种自动的，无意识的经验，看到颜色时，看到数字，字母或文字的印刷页。先前的研究已经证明，联觉是一种真正的知觉现象，但关键的是，所有这些实验都使用了高对比度的字母和数字。我们的联觉者JC曾经说过，他的联觉颜色的强弱取决于字素的对比度高低。为了测试这一点，我们要求JC对三个不同日期的不同对比度的字母对他的经历的强度进行评价。JC对他的联觉颜色的强度的评价随着对比度的增加而单调下降，这表明他的联觉颜色在低对比度下减少或不存在。为了更精确地量化这一影响，我们然后测试了JC对我们的嵌入图形任务（Ramachandran和Hubbard，2001 a）和拥挤任务（Ramachandran和Hubbard，2001 b）的修改版本，通过呈现不同的字素和背景之间的对比度显示。在我们的嵌入图形任务的对比变量中的行为数据显示，JC在高对比度下的表现明显优于对照组，复制了我们以前的发现。然而，在低对比度下，这种优势被消除了，这与他关于较弱或缺乏颜色的报告一致。一个类似的，但较弱的结果模式被发现在我们的拥挤任务的修改版本。这些结果表明，JC的联觉颜色可能是在视觉加工的对比度依赖阶段引起的。我们建议，专门用于字母和数字字形识别的梭状回区域已被证明以对比度依赖的方式介导JC的联觉颜色。然而，这是否适用于所有的字形-颜色联觉者，或者只适用于我们所说的低联觉者，还有待观察。
Grapheme-color synesthesia is an automatic, involuntary experience of seeing colors when viewing numbers, letters or words on a printed page. Previous research has demonstrated that synesthesia is a genuine perceptual phenomenon, but crucially, all of these experiments have used high-contrast letters and numbers. Our synesthete, JC, anecdotally reported that the strength of his synesthetic colors varied depending on whether the graphemes were presented in high or low contrast. To test this, we asked JC to rate the strength of his experiences to letters of different contrasts on three different dates. JC's ratings of the strength of his synesthetic colors consistently declined monotonically with contrast, suggesting that his synesthetic colors were reduced or absent at low contrasts. To more precisely quantify the impact of this, we then tested JC on modified versions of our embedded figures task (Ramachandran and Hubbard, 2001a) and crowding task (Ramachandran and Hubbard, 2001b) by presenting displays with varying contrast between the graphemes and the background. Behavioral data in the contrast variant of our embedded figures task showed that JC performed significantly better than controls at high contrast, replicating our previous findings. However, at low contrast this advantage was eliminated, consistent with his reports of weaker or absent colors. A similar, but weaker pattern of results was found in the modified version of our crowding task. These results suggest that JC's synesthetic colors may be elicited at contrast dependent stages of visual processing. We propose that regions of the fusiform gyrus specialized for letter and number grapheme recognition that have been shown to respond in a contrast dependent manner mediate JC's synesthetic colors. However, whether this is true for all grapheme-color synesthetes or is only true of the group we refer to as lower synesthetes, remains to be seen.