Multicolored words: Uncovering the relationship between reading mechanisms and synesthesia

Grapheme-color and lexical-color synesthesia, the association of colors with letters and words, respectively, are some of the most commonly studied forms of synesthesia, yet relatively little is known about how synesthesia arises from and interfaces with the reading process. To date, synesthetic experiences in reading have only been reported in relation to a word's graphemes and meaning. We present a case study of WBL, a 21-year old male who experiences synesthetic colors for letters and words. Over 3 months, we obtained nearly 3000 color judgments for visually presented monomorphemic, prefixed, suffixed, and compound words as well as judgments for pseudocompound words (e.g., carpet), and nonwords. In Experiment 1, we show that word color is nearly always determined by the color of the first letter. Furthermore, WBL reported two separate colors for prefixed and compound words approximately 14% of the time, with the additional color determined by the first letter of the second morpheme. In Experiment 2, we further investigated how various morphological factors influenced WBL's percepts using the compound norms of Juhasz, Lai, and Woodcock (2014). In a logistic regression analysis of color judgments for nearly 400 compounds, we observed that the likelihood that WBL would perceive a compound as bearing 1 lexical color or 2 lexical colors was influenced by a variety of factors including stem frequency, compound frequency, and the relationship between the meaning of the compound and the meaning of its stems. This constitutes the first study reporting an effect of morphological structure in synesthesia and demonstrates that synesthetic colors result from a complex interaction of perceptual, graphemic, morphological, and semantic factors.