Department of Psychology, University of California, San Diego, San Diego, CA, USA.
Brain and Cognition, Psychology Department, University of Amsterdam, Amsterdam, The Netherlands.
Cortex. 2018 Feb;99:375-389. doi: 10.1016/j.cortex.2017.12.003. Epub 2017 Dec 14.
Grapheme-color synesthesia is a neurological phenomenon in which viewing a grapheme elicits an additional, automatic, and consistent sensation of color. Color-to-letter associations in synesthesia are interesting in their own right, but also offer an opportunity to examine relationships between visual, acoustic, and semantic aspects of language. Research using large populations of synesthetes has indeed found that grapheme-color pairings can be influenced by numerous properties of graphemes, but the contributions made by each of these explanatory factors are often confounded in a monolingual dataset (i.e., only English-speaking synesthetes). Here, we report the first demonstration of how a multilingual dataset can reveal potentially-universal influences on synesthetic associations, and disentangle previously-confounded hypotheses about the relationship between properties of synesthetic color and properties of the grapheme that induces it. Numerous studies have reported that for English-speaking synesthetes, "A" tends to be colored red more often than predicted by chance, and several explanatory factors have been proposed that could explain this association. Using a five-language dataset (native English, Dutch, Spanish, Japanese, and Korean speakers), we compare the predictions made by each explanatory factor, and show that only an ordinal explanation makes consistent predictions across all five languages, suggesting that the English "A" is red because the first grapheme of a synesthete's alphabet or syllabary tends to be associated with red. We propose that the relationship between the first grapheme and the color red is an association between an unusually-distinct ordinal position ("first") and an unusually-distinct color (red). We test the predictions made by this theory, and demonstrate that the first grapheme is unusually distinct (has a color that is distant in color space from the other letters' colors). Our results demonstrate the importance of considering cross-linguistic similarities and differences in synesthesia, and suggest that some influences on grapheme-color associations in synesthesia might be universal.
文字-颜色联觉是一种神经现象，其中看到一个文字会引发额外的、自动的、一致的颜色感觉。联觉中的颜色-字母联想本身很有趣，但也为研究语言的视觉、听觉和语义方面之间的关系提供了机会。使用大量的联觉者进行的研究确实发现，文字-颜色的配对可以受到文字的许多特性的影响，但这些解释因素中的每一个因素的贡献在单语数据集（即，只有英语联觉者）中往往是混淆的。在这里，我们报告了第一个如何使用多语言数据集揭示对联觉联想可能具有普遍影响的例子，并阐明了关于联觉颜色的特性与引起它的文字的特性之间的关系的以前混淆的假设。许多研究报告说，对于讲英语的联觉者，“A”比随机预测更常被涂成红色，并且已经提出了几个解释因素可以解释这种关联。使用一个五语言数据集（母语为英语、荷兰语、西班牙语、日语和韩语的人），我们比较了每个解释因素的预测，并表明只有一个有序的解释在所有五种语言中都做出了一致的预测，这表明英语的“A”是红色的，因为联觉者的字母表或音节的第一个文字通常与红色相关联。我们提出，第一个文字和红色之间的关系是一个不寻常的独特顺序位置（“第一”）和一个不寻常的独特颜色（红色）之间的关联。我们测试了这个理论的预测，并证明了第一个文字是非常独特的（它的颜色在颜色空间中与其他字母的颜色相去甚远）。我们的结果表明，考虑联觉中的跨语言相似性和差异性的重要性，并表明联觉中文字-颜色联想的一些影响可能是普遍的。
