Yue Shimeng, Chen Lihan
School of Psychological and Cognitive Sciences, Peking University, Beijing 100871, China.
Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100871, China.
Brain Sci. 2022 Oct 17;12(10):1400. doi: 10.3390/brainsci12101400.
Number-color synesthesia is a condition in which synesthetes perceive numbers with concurrent experience of specific, corresponding colors. It has been proposed that synesthetic association exists primarily between representations of Arabic digit graphemes and colors, and a secondary, semantic connection between numerosity and colors is built via repeated co-activation. However, this distinction between the graphemic and semantic pathways of synesthetic number-color connection has not been empirically tested. The current study aims to dissociate graphemic and semantic aspects of color activations in number-color synesthesia by comparing their time courses. We adopted a synesthetic priming paradigm with varied stimuli onset asynchronies (SOAs). A number (2-6, prime) was presented in one of three notations: digit, dice, or non-canonical dot pattern, and a color patch (target) appeared with an SOA of 0, 100, 300, 400, or 800 ms. Participants reported the color as quickly as possible. Using the congruency effect (i.e., shorter reaction time when target color matched the synesthetic color of number prime) as an index of synesthetic color activation level, we revealed that the effect from the graphemic pathway is quick and relatively persistent, while the effect from the semantic pathway unfolds at a later stage and is more transient. The dissociation between the graphemic and semantic pathways of synesthesia implies further functional distinction within "conceptual synesthesia", which has been originally discussed as a unitary phenomenon. This distinction has been demonstrated by the differential time courses of synesthetic color activations, and suggested that a presumed, single type of synesthesia could involve multiple mechanisms.
数字 - 颜色联觉是一种联觉者在感知数字时会同时体验到特定对应颜色的状况。有人提出，联觉关联主要存在于阿拉伯数字字形的表征与颜色之间，而数量与颜色之间的次要语义联系是通过反复的共同激活建立起来的。然而，联觉数字 - 颜色联系的字形和语义路径之间的这种区别尚未得到实证检验。当前的研究旨在通过比较数字 - 颜色联觉中颜色激活的时间进程来区分字形和语义方面。我们采用了一种具有不同刺激起始异步性（SOA）的联觉启动范式。一个数字（2 - 6，启动刺激）以三种符号表示之一呈现：数字、骰子或非标准点阵模式，然后一个颜色块（目标刺激）在0、100、300、400或800毫秒的SOA下出现。参与者尽快报告颜色。使用一致性效应（即当目标颜色与数字启动刺激的联觉颜色匹配时反应时间更短）作为联觉颜色激活水平的指标，我们发现字形路径的效应快速且相对持久，而语义路径的效应在后期展开且更短暂。联觉的字形和语义路径之间的分离意味着在“概念性联觉”（最初被视为一种单一现象）中存在进一步的功能差异。这种差异已通过联觉颜色激活的不同时间进程得到证明，并表明一种假定的单一类型的联觉可能涉及多种机制。
