Article

Why is the synesthete’s “A” red? Using a five-language dataset to disentangle the effects of shape, sound, semantics, and ordinality on inducer-concurrent relationships in grapheme-color synesthesia

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Abstract

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.

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... It may be that there are trends in the dominance of certain letters as there are trends in their associated colours (e.g. [9,16,[35][36][37]), which could be connected to the processes involved in recognizing graphemes and words and therefore uncover a new tool for studying these psycholinguistics mechanisms. On the other hand, a letter's dominance may also be linked to its perceptual form, such that more visually complex, repeated, bold-faced, or capital letters may be more dominant. ...
... Several well-known papers have done this for specific aspects of synaesthetic experience-for instance, Rich et al. [9] and Simner et al. [37] on the population-level trends in letter-colour pairings. By sampling from a large number of synaesthetes and non-synaesthetes, these studies established that particular letters tend to have a particular colour concurrent-for example, A is famously red (at least in English; [16,35]), Q purple, D brown, etc. That is, these studies set the groundwork for future research investigating why these trends exist by first acquiring colours and letters from a large sample. ...
... Luckily, working alone is not necessary. Recent papers combining data from different laboratories in different languages have showcased the value of collaboration across institutions and nations [35,36], providing insight across populations and languages that would have been prohibitively expensive or impractical in isolation. Establishing a baseline successfully, with participation from synaesthetes in sufficient numbers to develop a clearer picture of synaesthesia as a phenomenon, should be a priority of the synaesthesia research community as a whole, in the interest of creating resources and challenging assumptions that enhance the entire community's ability to ask and answer good scientific questions. ...
Article
In this paper, I present arguments and suggestions for the improvement of the scientific study of synaesthesia, and particularly grapheme-colour synaesthesia in relation to psycholinguistic research, although the principles I advocate can be easily adapted to any subfield of synaesthesia study. I postulate that the current state of research on synaesthesia in general, and on grapheme-colour synaesthesia in particular, suffers from a lack of exploratory evidence and essential groundwork upon which to build hypothesis-testing studies. In particular, I argue that synaesthesia research has been artificially bounded by assumptions about the nature of synaesthetic experiences, which constrain both the questions that researchers ask and the way in which they go about answering those questions. As a specific example, I detail how much of the current research on grapheme-colour synaesthesia is built to accommodate two major assumptions about the nature of colours for letters and for words—assumptions which I will contend are not universally true, and the exceptions to which point to a much richer and heterogeneous understanding of synaesthetic experience than current research practices capture. The top-down predetermination of what is important or meaningful to measure, and what is not, has subsequently impeded a full understanding of what synaesthesia is and how it works. I argue that these assumptions must be carefully addressed and evaluated, both for the particular case of grapheme-colour synaesthesia and for the field as a whole, to move towards a holistic and fruitful understanding of synaesthesia as a phenomenon and as a tool to study language, thought and perception. To that end, I propose specific recommendations for synaesthesia researchers to solidify and expand their understanding and to capture the actual experience of synaesthetes. This article is part of a discussion meeting issue ‘Bridging senses: novel insights from synaesthesia’.
... The few existing studies of synesthesia in other languages suggest that both types of RF might exist. At least one RF is plausibly universal: Root et al. (2018) found that the grapheme in the first ordinal position tends to be red in English, Spanish, Dutch, Japanese, and Korean. However, at least one RF might be language-specific: grapheme pronunciation influences grapheme-color associations in native speakers of Japanese (Asano & Yokosawa, 2011) and Korean (Kang, Kim, Shin, & Kim, 2017), but not in native English speakers (Watson, Akins, & Enns, 2012). ...
... 27 native speakers of Japanese (3 males, 24 females; mean age 23.81, range 18-44) who self-reported as synesthetes were recruited via a website (see Asano & Yokosawa, 2011). Japanese synesthetes selected a color experienced for each of the 46 basic Hiragana characters from a palette of the 138 named W3C colors (for details, see Supplemental Text S1 in Root et al., 2018). ...
... Datasets from Dutch, English, Japanese, Korean, and Spanish include subjects that were reported in a previous international collaboration (Root et al., 2018). In the present work, we use the raw unfiltered data (even for the datasets that were preprocessed in a previous study) so that we can match the preprocessing steps between languages as closely as possible. ...
Article
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Grapheme-color synesthetes experience graphemes as having a consistent color (e.g., “N is turquoise”). Synesthetes’ specific associations (which letter is which color) are often influenced by linguistic properties such as phonetic similarity, color terms (“Y is yellow”), and semantic associations (“D is for dog and dogs are brown”). However, most studies of synesthesia use only English-speaking synesthetes. Here, we measure the effect of color terms, semantic associations, and non-linguistic shape-color associations on synesthetic associations in Dutch, English, Greek, Japanese, Korean, Russian, and Spanish. The effect size of linguistic influences (color terms, semantic associations) differed significantly between languages. In contrast, the effect size of non-linguistic influences (shape-color associations), which we predicted to be universal, indeed did not differ between languages. We conclude that language matters (outcomes are influenced by the synesthete’s language) and that synesthesia offers an exceptional opportunity to study influences on letter representations in different languages.
... Given our interest in repeated engagement with grapheme-colour associations as a core mechanism for the development of synaesthetic consistency, we further explored if the specific grapheme-colour associations in the continuous consistency test matched the non-random pattern of associations frequently reported in grapheme-colours synaesthesia (e.g., Mankin & Simner, 2017;Root et al., 2018;Simner et al., 2006;Witthoft et al., 2015). For the purpose of comparison with previous studies (cf. ...
... For the purpose of comparison with previous studies (cf. Root et al., 2018;Simner et al., 2005), we focused on letter-colour associations based on eleven basic colour terms (black, blue, brown, grey, green, magenta, orange, purple, red, white, and yellow;Berlin & Kay, 1991). Thus, originally selected colours were reduced to these colour terms by means of finding the smallest Euclidean distance between a chosen colour and the term of the nearest colour in CIELUV colour space of the continuous consistency test. ...
... Only letter-colour associations that were consistent within a given session and participant entered the following analysis. To test for non-random letter-colour associations, we followed the procedure described by Root et al. (2018). With an omnibus chi-squared goodness-of-fit test, we compared the distribution of colour choices for every letter (Supplemental Fig. 1 in SupplementalInformation.pdf) per group and session to the overall distribution of all chosen colours in the respective group and session (Fig. 5a). ...
Article
Synaesthetic consistency is the hallmark of synaesthesia and plays an important role in the definition and validation of synaesthesia. It has been hypothesised that the acquisition of initially unspecified synaesthetic associations is based on consolidation processes. Thus, we investigated in non-synaesthetes whether repeatedly engaging with grapheme-colour associations mimics the developmental trajectory of synaesthetic consistency in genuine grapheme-colour synaesthesia. This was the case for the two tested experimental groups, irrespective of whether they were instructed to memorize their chosen associations, but not for the passive control group. Moreover, consolidated associations of the experimental groups resembled those frequently found in genuine synaesthesia. Furthermore, the acquisition of consistent grapheme-colour associations resulted in a transfer of benefits to performance in recognition memory for abstract stimuli, as also found in genuine synaesthesia. Our findings suggest that consistent synaesthetic associations are based on consolidation processes due to repeated engagement with graphemes and colours.
... red) independent of its appearance or 'shape' (i.e. 'A', 'a', 'ɑ', 'A' or 'A' → red) [4,[21][22][23]. Importantly, even though this additionally activated synaesthetic experience is task-irrelevant, it is likely to be an integral part in event files in synaesthetes. ...
... Stimulus 'location' (left or right frame box) and even, more importantly, the stimulus 'colour' were task-irrelevant features. For synaesthetes, however, the involuntary perception of an additional synaesthetic colour concurrent is intimately coupled to the 'identity' of the target letter [23]. Hence, a task-irrelevant stimulus feature, namely the idiosyncratically perceived 'non-veridical colour', is automatically activated in synaesthetes whenever they are processing a letter. ...
Article
We continually perform actions that are driven by our perception and it is a commonly held view that only objectively perceived changes within the ‘real’ world affect behaviour. Exceptions are generally only made for mental health disorders associated with delusions and hallucinations where behaviour may be triggered by the experience of objectively non-existent percepts. Here, we demonstrate, using synaesthesia as a model condition (in N = 19 grapheme-colour synaesthetes), how objectively non-existent (i.e. non-veridical) but still non-pathological perceptions affect actions in healthy humans. Using electroencephalography, we determine whether early-stage perceptual processes (reflected by P1 and N1 event-related potential (ERP) components), or late-stage-integration processes (reflected by N2 component), underlie the effects of non-veridical perceptions on action control. ERP analysis suggests that even though the examined peculiarities and experimental variations are perceptual in nature, it is not early-stage perceptual processes, but rather higher-order executive control processes linking perceptions to the appropriate motor response underlying this effect. Source localization analysis implicates activation within medial frontal cortices in the effect of how irrelevant non-veridical perceptions modulate behaviour. Our results challenge common conceptions about the determinants of human behaviour but can be explained by well-established theoretical frameworks detailing the link between perception and action. This article is part of a discussion meeting issue ‘Bridging senses: novel insights from synaesthesia’.
... For instance, both overwhelmingly identified the grapheme A as red (cf. Root et al., 2018;Rouw, Case, Gosavi, & Ramachandran, 2014, for recent cross-linguistic confirmations). Using temporally spaced testing (one to three weeks for controls, and two to four months for synesthetes), they also showed that synesthetic participants were far more temporally consistent in their color choices (92%) than controls (32%), despite the longer time interval for testing synesthetes. ...
... Just as lexicalization patterns in the domain of color can shape low-level processes of color perception (Roberson, Pak, & Hanley, 2008), so phonemic structure may shape cross-modal associations. This is one place where linguistic diversity in phonetics, phonology, and orthography can be used to learn more about the mechanisms underlying vowel-color associations and to tease apart the roles of acoustic, phonemic, and graphemic features in cross-modal associations (Root et al., 2018;van Leeuwen et al., 2016). ...
Article
Full-text available
We report associations between vowel sounds, graphemes, and colors collected online from over 1,000 Dutch speakers. We also provide open materials, including a Python implementation of the structure measure and code for a single-page web application to run simple cross-modal tasks. We also provide a full dataset of color–vowel associations from 1,164 participants, including over 200 synesthetes identified using consistency measures. Our analysis reveals salient patterns in the cross-modal associations and introduces a novel measure of isomorphism in cross-modal mappings. We found that, while the acoustic features of vowels significantly predict certain mappings (replicating prior work), both vowel phoneme category and grapheme category are even better predictors of color choice. Phoneme category is the best predictor of color choice overall, pointing to the importance of phonological representations in addition to acoustic cues. Generally, high/front vowels are lighter, more green, and more yellow than low/back vowels. Synesthetes respond more strongly on some dimensions, choosing lighter and more yellow colors for high and mid front vowels than do nonsynesthetes. We also present a novel measure of cross-modal mappings adapted from ecology, which uses a simulated distribution of mappings to measure the extent to which participants’ actual mappings are structured isomorphically across modalities. Synesthetes have mappings that tend to be more structured than nonsynesthetes’, and more consistent color choices across trials correlate with higher structure scores. Nevertheless, the large majority (~ 70%) of participants produce structured mappings, indicating that the capacity to make isomorphically structured mappings across distinct modalities is shared to a large extent, even if the exact nature of the mappings varies across individuals. Overall, this novel structure measure suggests a distribution of structured cross-modal association in the population, with synesthetes at one extreme and participants with unstructured associations at the other.
... red) independent of its appearance or 'shape' (i.e. 'A', 'a', 'ɑ', 'A' or 'A' → red) [4,[21][22][23]. Importantly, even though this additionally activated synaesthetic experience is task-irrelevant, it is likely to be an integral part in event files in synaesthetes. ...
... Stimulus 'location' (left or right frame box) and even, more importantly, the stimulus 'colour' were task-irrelevant features. For synaesthetes, however, the involuntary perception of an additional synaesthetic colour concurrent is intimately coupled to the 'identity' of the target letter [23]. Hence, a task-irrelevant stimulus feature, namely the idiosyncratically perceived 'non-veridical colour', is automatically activated in synaesthetes whenever they are processing a letter. ...
Article
We continually perform actions that are driven by our perception and it is a commonly held that only objectively perceived changes within the ‘real’ world affect behaviour. Exceptions are only made for mental health disorders associated with delusions and hallucinations where behavior may be triggered by the experience of objectively non-existent percepts. Here we demonstrate, using synaesthesia as a model condition (in N=19 grapheme-colour synaesthetes), how objectively non-existent (i.e. non-veridical) but still non-pathological perceptions affect actions in healthy humans. We use electrophysiological (EEG) methods to determine whether early-stage perceptual processes (reflected by P1 and N1 event-related potential components), or late stage-integration processes, are underlying the effects of non-veridical perceptions on action control. ERP analysis suggests that even though the examined peculiarities and experimental variations are perceptual in nature it is not early-stage perceptual processing, but rather higher-order executive control processes linking perceptions to the appropriate motor response underlying this effect. Source localization analysis implicates activation within medial frontal cortices in the effect of how irrelevant non-veridical perceptions modulate behaviour. Our results challenge common conceptions about the determinants of human behaviour but can be explained by well-established theoretical frameworks detailing the link between perception and action.
... red) independent of its appearance or 'shape' (i.e. 'A', 'a', 'ɑ', 'A' or 'A' → red) (Dixon et al., 2006;Grossenbacher and Lovelace, 2001;Nikolić et al., 2011;Root et al., 2018). Importantly, even though this additionally activated synesthetic experience is task-irrelevant it is likely to be an integral part in event files in synesthetes. ...
... Stimulus 'location' (left or right frame box) and even more importantly, the stimulus 'colour' were task-irrelevant features. For synaesthetes, however, the involuntary perception of an additional synaesthetic colour concurrent is intimately coupled to the 'identity' of the target letter (Root et al., 2018). Hence, a task-irrelevant stimulus feature, namely the idiosyncratically perceived 'non-veridical colour', is automatically activated in synesthetes whenever a letter is presented to them. ...
Preprint
We continually perform actions driven by our perception and it is commonly held that only objectively perceived changes within the 'real' world affect behaviour. Exceptions are usually only made for clinical conditions associated with hallucinations, where objectively non-existent percepts can influence behavior. Using synaesthesia as a model condition, we show that even in healthy populations irrelevant non-veridical precepts exert an effect on action. By non-veridical we refer to stimulus dimensions that are only subjectively perceived to be there. Applying electrophysiological (EEG) methods, we show that although these examined peculiarities are perceptual in nature, not primarily perceptual processes underlie the effects of irrelevant non-veridical perceptions on actions. Rather, high-order processes linking perceptions and motor control in medial frontal cortices reflect the underlying mechanism how irrelevant non-veridical perceptions modulate behaviour. Our results challenge assumptions about the determinants of healthy human behaviour but can be embedded within existing frameworks detailing perception action interactions.
... This was the first time in history that a statistical counting study had been conducted, which is topical today (Simner et al. 2005). • Gruber set the starting point for cross-and multilingual studies on grapheme-color synesthesia, which is topical today (Asano et al. 2019;Root et al. 2018;Watson et al. 2017). • The growth of scientific literature on synesthesia in France increased in the years after the congress: above all, monographs by Suarez de Mendoza (1890), Millet (1892), and Flournoy (1893); an extensive article by Binet (1892a), published five times in four languages; and a entry on audition colorée in the Dictionnaire de Physiologie (Nuel 1895). ...
Article
Full-text available
At the first ever worldwide international conference of psychology in Paris, 1889, one symposium included a round-table event devoted entirely to the neurodevelopmental condition of synesthesia. Details of this seminal gathering on synesthesia and its international reception have been lost to historical obscurity. A synesthesia study committee emerged from this meeting, as well as a new research tool. Moreover, the scientific findings discussed during this symposium would be echoed over a hundred years later, when a new wave of synesthesia research in the late-twentieth century arose. This article sheds new light on this seminal gathering and aims to answer the following historical questions: Why was synesthesia included in this conference? What science was discussed? Who were the members of the committee and how did they come to be involved? What were their contributions to synesthesia research before, during, and after the conference? What has history shown us about the impact of this symposium on the science of synesthesia?
... Estimates suggest that more than 1.4% of the general population have grapheme-colour synaesthesia; this means that worldwide there may be more than 90 million individuals who have it [13,14]. Lastly, and perhaps the most important of these reasons is that grapheme-colour synaesthesia offers a unique lens through which to study and understand the biology of language [15][16][17][18]. ...
Article
Full-text available
Synaesthesia refers to a diverse group of perceptions. These unusual perceptions are defined by the experience of concurrents; these are conscious experiences that are catalysed by attention to some normally unrelated stimulus, the inducer . In grapheme-colour synaesthesia numbers, letters, and words can all cause colour concurrents , and these are independent of the actual colour with which the graphemes are displayed. For example, when seeing the numeral ‘3’ a person with synaesthesia might experience green as the concurrent irrespective of whether the numeral is printed in blue, black, or red. As a trait, synaesthesia has the potential to cause both positive and negative effects. However, regardless of the end effect, synaesthesia incurs an initial cost when compared with its equivalent example from normal perception; this is the additional processing cost needed to generate the information on the concurrent . We contend that this cost can be reduced by mirroring the concurrent in the environment. We designed the Digital-Colour Calculator (DCC) app, allowing each user to personalise and select the colours with which it displays its digits; it is the first reported example of a device/approach that leverages the concurrent. In this article we report on the reactions to the DCC for a sample of fifty-three synaesthetes and thirty-five non-synaesthetes. The synaesthetes showed a strong preference for the DCC over its normal counterpart. The non-synaesthetes showed no obvious preference. When using the DCC a subsample of the synaesthete group showed consistent improvement in task speed (around 8%) whereas no synaesthete showed a decrement in their speed.
... We analysed grapheme-colour associations in a combination of data from synaesthetes used in a previous study [42] and newly collected data. All subjects had completed the Eagleman Synesthesia Battery (synaesthete.org), ...
Article
Full-text available
Grapheme–colour synaesthesia is a neurological phenomenon in which linguistic symbols evoke consistent colour sensations. Synaesthesia is believed to be influenced by both genetic and environmental factors, but how these factors interact to create specific associations in specific individuals is poorly understood. In this paper, we show that a grapheme–colour association in adult synaesthetes can be traced to a particular environmental effect at a particular moment in childhood. We propose a model in which specific grapheme–colour associations are ‘locked in’ during development in children predisposed to become synaesthetes, whereas grapheme–colour associations remain flexible in non-synaesthetes. We exploit Western gender–colour stereotypes to test our model: we found that young girls in general tend to associate their first initial with the colour pink. Consistent with our model, adult female synaesthetes are influenced by their childhood environment: they associate their first initial with pink. Adult female non-synaesthetes do not show this bias. Instead, in our study, non-synaesthetes tended to associate their first initial with their current favourite colour. The results thus support the ‘locking in’ model of synaesthesia, suggesting that synaesthetic associations can be used as a ‘time capsule’, revealing childhood influences on adult linguistic associations. Grapheme–colour synaesthesia may thus offer an extraordinary opportunity to study linguistic development. This article is part of a discussion meeting issue ‘Bridging senses: novel insights from synaesthesia’.
... Unfortunately, he died too young to publish on it. A recent study with a five-language data set confirmed the necessity to consider cross-linguistic comparisons in grapheme-color synesthesia (Root et al. 2018). ...
Article
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Synesthesia is a rare neurological trait that causes unusual, often cross-sensory, experiences (e.g., seeing colors when listening to music). This article traces the history of synesthesia in the period 1876 to 1895. In this period, there was considerable debate over the nature of synesthesia, its causes, and how it should be named. The issue also attracted the leading thinkers of the time and, within a few years, the number of reported cases of synesthesia jumped from around ten to more than 100. For this reason, this period can be regarded as the “golden age” for synesthesia research in the nineteenth century. In this time, scientists debated whether synesthesia was a form of pathology or an alternative manifestation of intelligence. The differing roles of heredity and environment were contested, and there were several explanations proposed as to its neural basis. These enquiries went to the heart of the debate as to whether synesthetic experiences are special in any way or, instead, a more vivid manifestation of a more general capacity for forming associations.
... Similarly, the color associated with the sound for the word 'Cem' changed when Hale got married to a man named 'Cem.' Root et al. claimed that some letters are associated with the same color in plenty of languages (32). Even though our respondents were siblings with a shared genetic pool and environment, they experienced varied associated colors when they heard the same sounds. ...
Preprint
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Current research aims to explore, understand and describe the subjective experiences of synesthesia among six self-reported synesthete siblings. We conducted two studies, one quantitative and one qualitative, for this purpose. The first study aimed to measure whether six siblings actually had synesthesia experiences. Six synesthete siblings and their eighteen non-synesthete peers participated the study 1. First, participants filled out the Eagleman Synesthesia Test Battery - Synesthesia Type Scale. Then, we asked the participants to match some words that we randomly selected from the Turkish dictionary with colors on a color scale. Both cross-sectional and longitudinal compositions showed that six siblings matched words with specific colors compared to their non-synesthete peers, and these colors hardly change over time. In study 2, we interviewed these siblings and aimed to investigate their synesthetic experiences using an interpretative phenomenological analysis approach. We verbatim transcribed the interviews, and results showed that three main themes emerged, which were: (1) The nature of the synesthesia experience: Is it really rare?, (2) Details of the synesthesia experience, (3) Time and experience: It can change. The third superordinate theme has a subordinate theme, which is the stability of the associated colors within participants. We discussed the findings in the context of the persistence and changeability of the synesthetic experience and the uniqueness seen among siblings even when raised in the same environment.
... Synesthetes. We analyzed grapheme-color associations in a combination of data from synesthetes used in a previous study (Root et al., 2017) and newly-collected data. All subjects had completed the Eagleman Synesthesia Battery (synesthete.org), ...
... Hyperconnectivity between brain areas leads, over time, to an increase in the strength of these synesthetic concurrents. [64,65] Thus, it seems plausible that in ASMR and misophonia a genetic predisposition might interact with environmental factors to shape responses that become more consistent, automatic and stronger over time. Moreover, the experienced emotion, in predisposed individuals, might be part of an iterative process with the response strengthening every time the trigger occurs. ...
Article
We propose that synesthetic cross‐activation between the primary auditory cortex and the anatomically adjacent insula may help explain two puzzling conditions—autonomous sensory meridian response (ASMR) and misophonia—in which quotidian sounds involuntarily trigger strong emotional responses. In ASMR the sounds engender relaxation, while in misophonia they trigger an aversive response. The insula both plays an important role in autonomic nervous system control and integrates multiple interoceptive maps representing the physiological state of the body to substantiate a dynamic representation of emotional wellbeing. We propose that in ASMR cross‐activation of the map for affective (sensual) touch leads to an increase in subjective wellbeing and parasympathetic activity. Conversely, in misophonia the effect of the cross‐activation is to decrease emotional wellbeing and increase sympathetic activity. Our hypothesis also illuminates the connection between hearing and wellbeing more broadly and helps explain why so many people experience decreased wellbeing from modern urban soundscapes.
... Finally, there are some limitations in our study. First, only 11 focal colours were used, although some relevant studies also used 11 colours only (e.g., Rich et al., 2005;Simner et al., 2005;Wrembel, 2009;Root et al., 2018). A wider choice of colour would allow a more comprehensive investigation. ...
Article
Previous studies showed similar mappings between sounds and colours for synaesthetes and non-synaesthetes alike, and proposed that common mechanisms underlie such cross-modal association. The findings between vowels and colours, and between pitch and lightness, were investigated separately, and it was also unknown how language background would influence such association. The present study investigated the cross-modal association between sounds (vowels and pitch) and colours in a tone language using three groups of non-synaesthetes: Cantonese (native), Mandarin (foreign, tonal), and English (foreign, non-tonal). Strong associations were found between /a/ and red, /i/ with light colours, and /u/ with dark colours, and a robust pitch effect with a high tone eliciting lighter colours than a low tone in general. The pitch effect is stronger than the vowel associations. Significant differences among the three language groups in colour choices of other vowels and the strength of association were found, which demonstrate the language-specificity of these associations. The findings support the notion that synaesthesia is a general phenomenon, which can be influenced by linguistic factors.
... However, alternative explanations based on higher-level semantic associations (Chiou and Rich, 2014) cannot be completely ruled out. First, the correlation between orthography and synesthetic experience does not explain why a particular texture gets associated with a particular Braille pattern in the first place (Root et al., 2018). Moreover, according to CB ′ subjective report, number synesthesia emerged when CB was about 4 years old, two-three years before he learned the Braille alphabet. ...
Article
Synesthesia represents an atypical merging of percepts, in which a given sensory experience (e.g., words, letters, music) triggers sensations in a different perceptual domain (e.g., color). According to recent estimates, the vast majority of the reported cases of synesthesia involve a visual experience. Purely non-visual synesthesia is extremely rare and to date there is no reported case of a congenitally blind synesthete. Moreover, it has been suggested that congenital blindness impairs the emergence of synesthesia-related phenomena such as multisensory integration and cross-modal correspondences between non-visual senses (e.g., sound-touch). Is visual experience necessary to develop synesthesia? Here we describe the case of a congenital blind man (CB) reporting a complex synesthetic experience, involving numbers, letters, months and days of the week. Each item is associated with a precise position in mental space and with a precise tactile texture. In one experiment we empirically verified the presence of number-texture and letter-texture synesthesia in CB, compared to non-synesthete controls, probing the consistency of item-texture associations across time and demonstrating that synesthesia can develop without vision. Our data fill an important void in the current knowledge on synesthesia and shed light on the mechanisms behind sensory crosstalk in the human mind.
Article
One of the fundamental questions about grapheme–colour synaesthesia is how specific associations between the graphemes and colours are formed. We addressed this question by focusing on the determinants of synaesthetic colours for Japanese Kanji characters (logographic characters) using a psycholinguistic approach. Study 1 explored the influence meaning has on synaesthetic colours for Kanji characters representing abstract meanings by examining synaesthetic colours for antonym pairs (i.e. characters with meanings opposed to each other) in Japanese synaesthetes. Results showed that semantic relations influenced the grapheme–colour associations for characters representing abstract meanings in the early stages of learning abstract Kanji, while the influence was reduced in the grapheme–colour associations for those learned later. Study 2 examined the effect that learning new sounds or meanings of graphemes has on synaesthetic colours for those graphemes. Japanese synaesthetes were taught new sounds or new meanings for familiar Kanji characters. Results indicated that acquiring new information for graphemes slightly but significantly reduced the test–retest grapheme–colour association consistency, suggesting that synaesthetic colours can be modulated to reflect the synaesthete's latest knowledge about graphemes. Implications of these findings are discussed from the perspective of the relationship between synaesthesia and grapheme learning. This article is part of a discussion meeting issue ‘Bridging senses: novel insights from synaesthesia’.
Article
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Nagata, N. (2019). Color and Synesthesia. Journal of the Color Science Association of Japan, 43(2), 111-114.
Article
People with spatial sequence synesthesia have clear and stable mental images of spatial arrays of numbers, days of the week, and months. The shapes of the arrays vary by individual. We conducted an experiment to estimate the shapes of spatial arrays in people without synesthesia. We presented a pair of Japanese characters that represent the days of the week on a display, and asked participants without synesthesia to state which day they thought came later by pressing a key that was congruent with the spatial position of the day shown. We then estimated the shape of the spatial array in the participants' mental space (mental weekday lines) from the distribution of the reaction times. We found that these ‘estimated mental weekday lines’ differed by individual, and that the shapes (straight or bent lines, U-shapes, zigzags, or triangles) were similar to the spatial arrays found in individuals with synesthesia. We then conducted simulations using a self-organizing map and found that differences in the shapes of the spatial arrays compared with those in individuals with synesthesia could be explained by the inputs to the network. These results support the hypothesis that interactions between spatial and ordinal/cardinal representations in both synesthetes and non-synesthetes develop under the influence of self-organizing learning.
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Determinants of synesthetic color choice for the Japanese logographic script, Kanji, were studied. The study investigated how synesthetic colors for Kanji characters, which are usually acquired later in life than other types of graphemes in Japanese language (phonetic characters called Hiragana and Katakana, and Arabic digits), are influenced by linguistic properties such as phonology, orthography, and meaning. Of central interest was a hypothesized generalization process from synesthetic colors for graphemes, learned prior to acquisition of Kanji, to Kanji characters learned later. Results revealed that color choices for Kanji characters depend on meaning and phonological information. Some results suggested that colors are generalized from Hiragana characters and Arabic digits to Kanji characters via phonology and meaning, respectively. Little influence of orthographic information was observed. The findings and approach of this study contributes to a clarification of the mechanism underlying grapheme-color synesthesia, especially in terms of its relationship to normal language processing.
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This study shows that biases exist in the associations of letters with colours across individuals both with and without grapheme-colour synaesthesia. A group of grapheme-colour synaesthetes were significantly more consistent over time in their choice of colours than a group of controls. Despite this difference, there were remarkable inter-subject agreements, both within and across participant groups (e.g., a tends to be red, b tends to be blue, c tends to be yellow). This suggests that grapheme-colour synaesthesia, whilst only exhibited by certain individuals, stems in part from mechanisms that are common to us all. In addition to shared processes, each population has its own distinct profile. Synaesthetes tend to associate higher frequency graphemes with higher frequency colour terms. For control participants, choices are influenced by order of elicitation, and by exemplar typicality from the semantic class of colours.
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Reviews colored-hearing synesthesia, in which sounds induce visual images (photisms). Colored hearing manifests correlations between dimensions of auditory and visual experience. Two general findings are that (a) the brightness of photisms varies with the brightness (density) of the inducing sounds and (b) the size of photisms varies with the size (volume) of the inducing sounds. In colored hearing produced by speech sounds, the induced hues and brightnesses can be related to the formant structures of the vowels. Synesthetes align dimensions on different modalities in ways that are qualitatively similar to the ways that nonsynesthetes align them (e.g., in phonetic symbolism). Synesthesia appears to be a cross-modal manifestation of connotative meaning in a pure sensory form; its inflexibility (compared to language) makes synesthesia less significant in adulthood than in childhood. (31/2 p ref)
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The authors conducted 3 sets of experiments. In the 1st set of experiments, participants made alphabetic position estimations. In the 2nd set, participants made interletter distance estimations. In the 3rd set, they made comparative judgments of the alphabetic order of a pair of letters. The results showed that participants had highly accurate ordinal level information about the alphabet in memory but that interval level information was systematically distorted. In addition, alphabetic serial information was found to be used in 2 distinct modes in memory, depending on whether the representation could be contained within the span of immediate memory.
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Several previous studies have suggested that basic decoding skills may develop less effectively in English than in some other European orthographies. The origins of this effect in the early (foundation) phase of reading acquisition are investigated through assessments of letter knowledge, familiar word reading, and simple nonword reading in English and 12 other orthographies. The results confirm that children from a majority of European countries become accurate and fluent in foundation level reading before the end of the first school year. There are some exceptions, notably in French, Portuguese, Danish, and, particularly, in English. The effects appear not to be attributable to differences in age of starting or letter knowledge. It is argued that fundamental linguistic differences in syllabic complexity and orthographic depth are responsible. Syllabic complexity selectively affects decoding, whereas orthographic depth affects both word reading and nonword reading. The rate of development in English is more than twice as slow as in the shallow orthographies. It is hypothesized that the deeper orthographies induce the implementation of a dual (logographic + alphabetic) foundation which takes more than twice as long to establish as the single foundation required for the learning of a shallow orthography.
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This study investigates the origins of specific letter-colour associations experienced by people with grapheme-colour synaesthesia. We present novel evidence that frequently observed trends in synaesthesia (e.g., A is typically red) can be tied to orthographic associations between letters and words (e.g., 'A is for apple'), which are typically formed during literacy acquisition. In our experiments, we first tested members of the general population to show that certain words are consistently associated with letters of the alphabet (e.g., A is for apple), which we named index words. Sampling from the same population, we then elicited the typical colour associations of these index words (e.g., apples are red) and used the letter → index word → colour connections to predict which colours and letters would be paired together based on these orthographic-semantic influences. We then looked at direct letter-colour associations (e.g., A→ red, B→ blue⋯) from both synaesthetes and non-synaesthetes. In both populations, we show statistically that the colour predicted by index words matches significantly with the letter-colour mappings: that is, A→ red because A is for apple and apples are prototypically red. We therefore conclude that letter-colour associations in both synaesthetes and non-synaesthetes are tied to early-learned letter-word associations.
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The use of Monte Carlo test procedures for significance testing, with smaller reference sets than are now generally used, is advocated. It is shown that, for given α = 1/n, n a positive integer, the power of the Monte Carlo test procedure is a monotone increasing function of the size of the reference set, the limit of which is the power of the corresponding uniformly most powerful test. The power functions and efficiency of the Monte Carlo test to the uniformly most powerful test are discussed in detail for the case where the test criterion is N(γ, 1). The cases when the test criterion is Student's t‐statistic and when the test statistic is exponentially distributed are considered also.
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To English speakers, the distinctions between blue and green, cup and glass, or cut and break seem self-evident. The intuition is that these words label categories that have an existence independent of language, and language merely captures the pre-existing categories. But cross-linguistic work shows that the named distinctions are not nearly as self-evident as they may feel. There is diversity in how languages divide up domains including color, number, plants and animals, drinking vessels and household containers, body parts, spatial relations, locomotion, acts of cutting and breaking, acts of carrying and holding, and more. Still, studies documenting variability across languages also uncover striking commonalities. Such commonalities indicate that there are sources of constraint on the variation. Both the commonalities and divergences carry important lessons for Cognitive Science. They speak to the causal relations among language, thought, and culture; the possibility of cross-culturally shared aspects of perception and cognition; the methods needed for studying general-purpose, nonlinguistic concepts; and how languages are learned. WIREs Cogn Sci 2013, 4:583-597. doi: 10.1002/wcs.1251 CONFLICT OF INTEREST: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website. © 2013 John Wiley & Sons, Ltd.
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The authors used Monte Carlo methods to assess the per-contrast and experimentwise Type I error rates of two post hoc tests of cellwise residuals and four post hoc tests of pairwise contrasts in 3 4 chi-square contingency tables. The six post hoc procedures were evaluated under three sample sizes and under the null hypotheses of independence and homogeneity. Results of the study indicate that the cellwise adjusted residual method provided adequate experimentwise Type I error rate control when appropriate adjustments to the alpha level were made, and the Gardner pairwise post hoc procedure provided several advantages over the other pairwise procedures. This was true for both the independence and homogeneity models.
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This chapter discusses the morphological development and evolutionary history of red sexual skin, and of sexual swellings, among female catarrhines. It examines the various facets of anatomy, endocrinology, behavior, and ecology in extant primates and considers some fossil evidence of catarrhine evolution. This comparative approach offers some clues to the mystery of why sexual skin has such a peculiar, discontinuous distribution among the extant Old World monkeys and apes. The chapter explains that sexual skin may have arisen by elaboration of the same type of vulval swelling and pinkness that occurs during estrus in many female prosimians. This hypothesis derives from the observations of sexual skin ontogeny and from comparative studies of its morphology in adult females. Sexual skin acts primarily as a sexually attractive distance cue in many species. It might therefore be adaptive in any environment where a monkey group spreads out over a wide area or fragments into subgroups. It is suggested that a complementary degree of penile elongation occurs in order to facilitate mating behavior in those species, where females have prominent swellings. The prominent penis of the chimpanzee is best explained on this basis, since the sexual swelling is enormous and adds considerably to the depth of the female's reproductive tract.
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Where individuals contest access to a resource, escalated physical fighting presents a risk to all involved. The requirement for mechanisms of conflict management has led to the evolution of a variety of decision rules and signals that act to reduce the frequency of aggression during competitive encounters. We examined strategies of conflict management in male mandrills (Mandrillus sphinx) living in two semi-free-ranging groups in Gabon. Adult male mandrills are large (31 kg), with long canines, making the costs of conflict potentially very high. We found that males formed dominance hierarchies, but that male–male relationships were characterized by avoidance, appeasement and ignoring. Fights were rare, but could result in death. Examination of the relationship between dominance and signaling showed that males use facial and gestural signals to communicate dominance and subordinance, avoiding escalated conflict. Male mandrills also possess rank-dependent red coloration on the face, rump and genitalia, and we examined the hypothesis that this coloration acts as a ‘badge of status’, communicating male fighting ability to other males. If this is the case, then similarity in color should lead to higher dyadic rates of aggression, while males that differ markedly should resolve encounters quickly, with the paler individual retreating. Indeed, appeasement (the ‘grin’ display), threats, fights and tense ‘stand-off’ encounters were significantly more frequent between similarly colored males, while clear submission was more frequent where color differences were large. We conclude that male mandrills employ both formal behavioral indicators of dominance and of subordination, and may also use relative brightness of red coloration to facilitate the assessment of individual differences in fighting ability, thereby regulating the degree of costly, escalated conflict between well-armed males.
Article
This article and the associated data and programs provided with it are intended to assist color engineers and scientists in correctly implementing the recently developed CIEDE2000 color-difference formula. We indicate several potential implementation errors that are not uncovered in tests performed using the original sample data published with the standard. A supplemental set of data is provided for comprehensive testing of implementations. The test data, Microsoft Excel spreadsheets, and MATLAB scripts for evaluating the CIEDE2000 color difference are made available at the first author's website. Finally, we also point out small mathematical discontinuities in the formula. © 2004 Wiley Periodicals, Inc. Col Res Appl, 30, 21–30, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20070
Article
Typically, the search for order in grapheme-color synesthesia has been conducted by looking at the frequency of certain letter-color associations. Here, we report stronger associations when second-order similarity mappings are examined--specifically, mappings between the synesthetic colors of letters and letter shape, frequency, and position in the alphabet. The analyses demonstrate that these relations are independent of one other. More strikingly, our analyses show that each of the letter-color mappings is restricted to one dimension of color, with letter shape and ordinality linked to hue, and letter frequency linked to luminance. These results imply that synesthetic associations are acquired as the alphabet is learned, with associations involving letter shape, ordinality, and frequency being made independently and idiosyncratically. Because these mappings of similarity structure between domains (letters and colors) are similar to those found in numerous other cognitive and perceptual domains, they imply that synesthetic associations operate on principles common to many aspects of human cognition.
Article
Although it is estimated that as many as 4% of people experience some form of enhanced cross talk between (or within) the senses, known as synaesthesia, very little is understood about the level of information processing required to induce a synaesthetic experience. In work presented here, we used a well-known multisensory illusion called the McGurk effect to show that synaesthesia is driven by late, perceptual processing, rather than early, unisensory processing. Specifically, we tested 9 linguistic-color synaesthetes and found that the colors induced by spoken words are related to what is perceived (i.e., the illusory combination of audio and visual inputs) and not to the auditory component alone. Our findings indicate that color-speech synaesthesia is triggered only when a significant amount of information processing has occurred and that early sensory activation is not directly linked to the synaesthetic experience.
Article
In one of the most common forms of synaesthesia, linguistic-colour synaesthesia, colour is induced by stimuli such as numbers, letters, days of the week, and months of the year. It is not clear, however, whether linguistic-colour synaesthesia is determined more by higher level semantic information--that is, word meaning--or by lower level grapheme or phoneme structure. To explore this issue, we tested whether colour is consistently induced by grapheme or phoneme form or word meaning in bilingual and trilingual linguistic-colour synaesthetes. We reasoned that if the induced colour was related to word meaning, rather than to the acoustic or visual properties of the words, then the induced colours would remain consistent across languages. We found that colours were not consistently related to word meaning across languages. Instead, induced colours were more related to form properties of the word across languages, particularly visual structure. However, the type of inducing stimulus influenced specific colour associations. For example, colours to months of the year were more consistent across languages than were colours to numbers or days of the week. Furthermore, the effect of inducing stimuli was also associated with the age of acquisition of additional languages. Our findings are discussed with reference to a critical period in language acquisition on synaesthesia.
Article
Languages differ widely in the size of their vowel inventories; however, cross-linguistic surveys indicate that certain vowels and vowel system configurations are preferred. A cross-linguistic comparison of the acoustic vowel categories of two languages that differ in vowel inventory size, namely, English and Spanish, was performed in order to reveal some of the language-specific and/or universal principles that determine the acoustic realization of the vowels of these two languages. This comparison shows that the precise location in the acoustic space of similar vowel categories across the two languages is determined, in part, by a language-specific base-of-articulation property. These data also suggest that the relatively crowded acoustic vowel space of English may be expanded with respect to the relatively uncrowded acoustic vowel space of Spanish; however, this effect is variable depending on the syllable context of the English vowels. Finally, the data indicate no difference in the tightness of within-category clustering for the large versus the small vowel inventory.
Article
Synesthesia is a conscious experience of systematically induced sensory attributes that are not experienced by most people under comparable conditions. Recent findings from cognitive psychology, functional brain imaging and electrophysiology have shed considerable light on the nature of synesthesia and its neurocognitive underpinnings. These cognitive and physiological findings are discussed with respect to a neuroanatomical framework comprising hierarchically organized cortical sensory pathways. We advance a neurobiological theory of synesthesia that fits within this neuroanatomical framework.
Article
Event-related fMRI was used to test the hypothesis that the visual word form area in the left fusiform gyrus holds a modality-specific and prelexical representation of visual words. Subjects were engaged in a repetition-detection task on pairs of words or pronounceable pseudo-words that could be written or spoken. The visual word form area responded only to written stimuli, not to spoken stimuli, independently of their semantic content. We propose that the occasional activation of the fusiform gyrus when listening to spoken words is due to the topdown recruitment of visual orthographic or object representations.
Article
For individuals with synaesthesia, stimuli in one sensory modality elicit anomalous experiences in another modality. For example, the sound of a particular piano note may be 'seen' as a unique colour, or the taste of a familiar food may be 'felt' as a distinct bodily sensation. We report a study of 192 adult synaesthetes, in which we administered a structured questionnaire to determine the relative frequency and characteristics of different types of synaesthetic experience. Our data suggest the prevalence of synaesthesia in the adult population is approximately 1 in 1150 females and 1 in 7150 males. The incidence of left-handedness in our sample was within the normal range, contrary to previous claims. We did, however, find that synaesthetes are more likely to be involved in artistic pursuits, consistent with anecdotal reports. We also examined responses from a subset of 150 synaesthetes for whom letters, digits and words induce colour experiences ('lexical-colour' synaesthesia). There was a striking consistency in the colours induced by certain letters and digits in these individuals. For example, 'R' elicited red for 36% of the sample, 'Y' elicited yellow for 45%, and 'D' elicited brown for 47%. Similar trends were apparent for a group of non-synaesthetic controls who were asked to associate colours with letters and digits. Based on these findings, we suggest that the development of lexical-colour synaesthesia in many cases incorporates early learning experiences common to all individuals. Moreover, many of our synaesthetes experienced colours only for days of the week, letters or digits, suggesting that inducers that are part of a conventional sequence (e.g. Monday, Tuesday, Wednesday...; A, B, C...; 1, 2, 3...) may be particularly important in the development of synaesthetic inducer-colour pairs. We speculate that the learning of such sequences during an early critical period determines the particular pattern of lexical-colour links, and that this pattern then generalises to other words.
Article
Synaesthesia, a neurological condition affecting approximately .05% of the population, is characterised by anomalous sensory perception: a stimulus in one sensory modality triggers an automatic, instantaneous, consistent response in another modality (e.g., sound evokes colour) or in a different aspect of the same modality (e.g., black text evokes colour). As evidence was limited to case studies based on self-report, the existence of synaesthesia was regarded with scepticism until the development of the Test of Genuineness (TOG) in 1987, which measures the consistency of stimulus-response linkage: synaesthetes typically score between 70-90% range, whereas controls typically score between 20-38%. However, the TOG had only limited ability to quantify the characteristics of visual synaesthesia. In this study, the revised Test of Genuineness (TOG-R), utilising the Pantone-based Cambridge Synaesthesia Charts, was given to 26 synaesthetes and 23 controls. Results confirmed that the TOG-R is equally accurate in the diagnosis of synaesthesia; synaesthetes scored significantly (t47 = 16.01, p < .001) higher (mean = 71.3%, SEM = 1.4%) than controls (mean = 33%, SEM = 2.0%). The TOG-R provides greater precision in quantifying the closeness of colour matches and enables a more detailed analysis of visual synaesthesia. Synaesthetes were phenotyped into broad- and narrowband based on their overall responsiveness to auditory stimuli, with bandwidth determined primarily by responsiveness to non-word stimuli. They were further sub-phenotyped based on responses to sub-groups of stimuli into word-colour (WC) and music-colour (MC). Development of this instrument has important implications for the diagnosis and phenotyping of visual synaesthesia.
Article
Synesthesia is an unusual condition in which stimulation of one modality evokes sensation or experience in another modality. Although discussed in the literature well over a century ago, synesthesia slipped out of the scientific spotlight for decades because of the difficulty in verifying and quantifying private perceptual experiences. In recent years, the study of synesthesia has enjoyed a renaissance due to the introduction of tests that demonstrate the reality of the condition, its automatic and involuntary nature, and its measurable perceptual consequences. However, while several research groups now study synesthesia, there is no single protocol for comparing, contrasting and pooling synesthetic subjects across these groups. There is no standard battery of tests, no quantifiable scoring system, and no standard phrasing of questions. Additionally, the tests that exist offer no means for data comparison. To remedy this deficit we have devised the Synesthesia Battery. This unified collection of tests is freely accessible online (http://www.synesthete.org). It consists of a questionnaire and several online software programs, and test results are immediately available for use by synesthetes and invited researchers. Performance on the tests is quantified with a standard scoring system. We introduce several novel tests here, and offer the software for running the tests. By presenting standardized procedures for testing and comparing subjects, this endeavor hopes to speed scientific progress in synesthesia research.