title: Type-based associations in grapheme-color synaesthesia revealed by response time distribution analyses.
abstract: Determining the nature of binding in grapheme-color synaesthesia has consequences for understanding the neural basis of synaesthesia and visual awareness in general. We evaluated type- and token-based letter-color binding using a synaesthetic version of the object-reviewing paradigm. Although mean response times failed to reveal any significant differences between synaesthetes and control participants, RT analyses with ex-Gaussian distributions revealed that the response facilitation in the synaesthesia group reflected type representations exclusively, while response facilitation in the control group, who learned letter-color associations, was dominated by token representations. Thus, letter-color associations in associator synaesthetes are type-based, and do not involve binding to object tokens, consistent with their subjective reports. Contrary to recent studies that failed to find differences between synaesthetes and non-synaesthetes with behavioral measures, response time distribution analyses indicate that color sensations in synaesthetes are not simply the extreme form of normal letter-color associations, and cannot be attributed to demand characteristics.
authors.affiliation: Graduate School of Human and Environmenral Studies, Kyoto University, Japan. saiki@cv.jinkan.kyoto-u.ac.jp
authors.forename: Jun
authors.initials: J
authors.lastname: Saiki
authors.forename: Ayako
authors.initials: A
authors.lastname: Yoshioka
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamamoto
mesh_terms: D000293:Adolescent; D000328:Adult; D001245:Association Learning; D016022:Case-Control Studies; D003118:Color Perception; D005260:Female; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual; D010468:Perceptual Disorders / Q000523:psychology*; D010775:Photic Stimulation; D011930:Reaction Time; D055815:Young Adult