We studied the patient JP who has exceptional abilities to draw complex geometrical images by hand and a form of acquired synesthesia for mathematical formulas and objects, which he perceives as geometrical figures. JP sees all smooth curvatures as discrete lines, similarly regardless of scale. We carried out two preliminary investigations to establish the perceptual nature of synesthetic experience and to investigate the neural basis of this phenomenon. In a functional magnetic resonance imaging (fMRI) study, image-inducing formulas produced (...) larger fMRI responses than non-image inducing formulas in the left temporal, parietal and frontal lobes. Thus our main finding is that the activation associated with his experience of complex geometrical images emerging from mathematical formulas is restricted to the left hemisphere. (shrink)

Despite some principal similarities, there is no systematic comparison between the different types of synesthesia . This comprehensive review compares the three principal types of synesthesia and focuses on their phenomenological features and their relation to different etiological models. Implications of this comparison for the validity of the different etiological models are discussed.Comparison of the three forms of synesthesia show many more differences than similarities. This is in contrast to their representation in the literature, where they are (...) discussed in many respects as being virtually similar. Noteworthy is the much broader spectrum and intensity with the typical drug-induced synesthesias compared to genuine and acquired synesthesias. A major implication of the phenomenological comparison in regard to the etiological models is that genuine and acquired synesthesias point to morphological substrates, while drug-induced synesthesia appears to be based on functional changes of brain activity. (shrink)

Visual information can be provided to blind users through sensory substitution devices that convert images into sound. Through extensive use to develop expertise, some blind users have reported visual experiences when using such a device. These blind expert users have also reported visual phenomenology to other sounds even when not using the device. The blind users acquired synthetic synaesthesia, with visual experience evoked by sounds only after gaining such expertise. Sensorimotor learning may facilitate and perhaps even be required to (...) develop expertise in the use of multimodal information. Furthermore, other areas where expertise is acquired in dividing attention amongst cross-modal information or integrating such information might also give rise to synthetic synaesthesia. (shrink)

In synesthesia, a certain stimulus (eg grapheme) is associated automatically and consistently with a stable perceptual-like experience (eg color). These associations are acquired in early childhood and remain robust throughout the lifetime. Synesthetic associations can transfer to novel inducers in adulthood as one learns a second language that uses another writing system. However, it is not known how long this transfer takes. We found that grapheme-color associations can transfer to novel graphemes after only a 10-minute writing exercise. Most (...) subjects experienced synesthetic associations immediately after learning a new Glagolitic grapheme. Using a Stroop task, we provide objective evidence for the creation of novel associations between the newly learned graphemes and synesthetic colors. Also, these associations generalized to graphemes handwritten by another person. The fast learning process and the generalization suggest that synesthesia begins at the semantic level of representation with the activation of a certain concept (the inducer), which then, uniquely for the synesthetes, activates representations at the perceptual level (the concurrent). Thus, the results imply that synesthesia is a much more flexible and plastic phenomenon than has been believed until now. (shrink)

Block (Trends Cogn Sci 7:285–286, 2003) and Prinz (PSYCHE 12:1–19, 2006) have defended the idea that SSD perception remains in the substituting modality (auditory or tactile). Hurley and Noë (Biol Philos 18:131–168, 2003) instead argued that after substantial training with the device, the perceptual experience that the SSD user enjoys undergoes a change, switching from tactile/auditory to visual. This debate has unfolded in something like a stalemate where, I will argue, it has become difficult to determine whether the perception (...) class='Hi'>acquired through the coupling with an SSD remains in the substituting or the substituted modality. Within this puzzling deadlock two new approaches have been recently suggested. Ward and Meijer (Conscious Cogn 19:492–500, 2010) describe SSD perception as visual-like but characterize it as a kind of artificially induced synaesthesia. Auvray et al. (Perception 36:416–430, 2007) and Auvray and Myin (Cogn Sci 33:1036–1058, 2009) suggest that SSDs let their users experience a new kind of perception. Deroy and Auvray (forthcoming) refine this position, and argue that this new kind of perception depends on pre-existing senses without entirely aligning with any of them. So, they have talked about perceptual experience in SSDs as going "beyond vision". In a similar vein, MacPherson (Oxford University Press, New York, 2011a) claims that “if the subjects (SSD users) have experiences with both vision-like and touch-like representational characteristics then perhaps they have a sense that ordinary humans do not” (MacPherson in Oxford University Press, New York, 2011a, p. 139). (shrink)

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 , 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. (shrink)

In this report, the phenomenology of two blind users of a sensory substitution device – “The vOICe” – that converts visual images to auditory signals is described. The users both report detailed visual phenomenology that developed within months of immersive use and has continued to evolve over a period of years. This visual phenomenology, although triggered through use of The vOICe, is likely to depend not only on online visualization of the auditory signal but also on the users’ previous (albeit (...) distant) experience of veridical vision (e.g. knowledge of shapes and visual perspective). Once established, the sensory substitution mapping between the auditory and visual domains is not confined to when the device is worn and, thus, may constitute an example of acquired synaesthesia. (shrink)

In her response to my "Seeing as a Non-Experiental Mental State: The Case from Synesthesia and Visual Imagery" Ophelia Deroy presents an argument for an interesting new account of synesthesia. On this account, synesthesia can be thought of as "a perceptual state (e.g. of a letter)" that is "changed or enriched by the incorporation of a conscious mental image (e.g. a color)." I reply that while this is a plausible account of some types of synesthesia, some (...) forms cannot be accounted for this way. (shrink)

Current research suggests that conceptual in?uences are primarily responsible for inducing synaesthesia, since numerous synaesthetic variants are triggered by linguistic symbols. These linguistic synaesthesias are the focus of the present review article. This article examines the literature on the transfer of synaesthetic colour-associations across languages and shows the scope of the linguistic mechanisms that are implicated. We review known evidence about the interaction between grapheme-colour synaesthesia and the acquisition of a second language, and specifically, we discuss cases of cross-linguistic transfer (...) in which a second language is learned later in life. Research on bilingual subjects has uncovered distinct representations in the brain for a mother tongue and for a later-acquired foreign language. Consequently, these differences have implications for synaesthesia associated with the writing systems of these different languages. By reviewing several individual cases of bilingual synaesthetes, we conclude that synaesthesia might have different types of influences on the acquisition of a second language, ranging from effects that support this learning to those that disturb it. (shrink)

Linguistic synesthesia (or synesthetic/intrafield/crossmodal metaphor) refers to crossmodal instances in which expressions in different sensory modalities are combined as in the case of sweet (taste) melody (hearing). Ullmann was among the first to show that synesthetic transfers seem to follow a potentially universal hierarchy that goes from the so-called “lower” (i.e., touch, taste and smell) to “higher” senses (i.e., hearing and sight). Several studies across languages, cultures, domains and text types seem to support the hierarchy in linguistic synesthesia (...) despite some crosslinguistic differences and varying explanations . To extend results to an underrepresented language and thus, to test the universality of the crossmodal hierarchy, 5,693 token cases of linguistic synesthesia in written and spoken Turkish were investigated using a general-purpose, large corpus. Token, type, and hapax legomena frequencies showed that although three backward and thus, hierarchy-inconsistent transfers (i.e., from taste to touch, from sight to smell and from sight to hearing) were more frequent than their hierarchy-consistent counterparts, forward transfers in the canonical direction were more frequent overall than the backward transfers in Turkish. We conclude that Turkish linguistic synesthesia complies with the hierarchy as a descriptive generalization. Results are discussed in comparison to the crossmodal use of sensory words in other languages. (shrink)

This study seeks to clarify the nature of linguistic synesthesia using a lexical-conceptual account. Based on a lexical analysis of Mandarin synesthetic usages, we find that linguistic synesthesia maps the metaphorical meaning between two domains; and linguistic synesthetic mappings and conceptual metaphoric mappings have similar behaviors when sense modalities are treated as conceptual domains that contain a set of mappings constrained by Mapping Principles. This lexical-conceptual account is designed to capture the fact that linguistic synesthesia involves mapping (...) between lexicalized concepts of sensory properties, instead of the real-time sensory input that is processed in neurological synesthesia. The incorporation of a lexical semantic view with the framework of Conceptual Metaphor Theory not only offers a coherent and comprehensive account for the nature of linguistic synesthesia, but also handles aspects of linguistic synesthesia previously only accounted for by non-metaphorical accounts. These design features make this proposal the most comprehensive account to fit the current data. Furthermore, by showing linguistic synesthesia as a type of metaphor, our study strengthens the role of conceptual metaphors as the link between the perceived world and our conceptualization of that world. (shrink)

Synesthesia literally means a “union of the senses” whereby two or more of the five senses that are normally experienced separately are involuntarily and automatically joined together in experience. For example, some synesthetes experience a color when they hear a sound, although many instances of synesthesia also occur entirely within the visual sense. In this paper, I first mainly engage critically with Sollberger’s view that there is reason to think that at least some synesthetic experiences can be viewed (...) as truly veridical perceptions, and not as illusions or hallucinations. Among other things, I explore the possibility that many forms of synesthesia can be understood as experiencing what I will call “second-order secondary properties,” that is, experiences of properties of objects induced by the secondary qualities of those objects. In doing so, I shed some light on why synesthesia is typically one-directional and its relation to some psychopathologies such as autism. (shrink)

It has been repeatedly suggested that synesthesia is intricately connected with unusual ways of exercising one’s mental imagery, although it is not always entirely clear what the exact connection is. My aim is to show that all forms of synesthesia are forms of (often very different kinds of) mental imagery and, further, if we consider synesthesia to be a form of mental imagery, we get significant explanatory benefits, especially concerning less central cases of synesthesia where the (...) inducer is not sensory stimulation. (shrink)

Synesthesia is a condition in which features that ordinarily are processed by distinct perceptual or cognitive streams are bound together in a single stream, yielding an aberrant perceptual, image‐like or thought‐like experience. One of the most common forms of synesthesia is grapheme‐color synesthesia. It is divided into two distinct forms: Projector synesthesia, which tends to be perception‐like, and associator synesthesia, which tends to be more like imagery or thought. There has been an ongoing debate in (...) philosophy about whether synesthesia can provide any insight into the philosophical question of the nature of perception. I argue here that at least some forms of projector synesthesia provide a challenge for reductive representationalism, the view that the phenomenal properties of perceptual experience is exhausted by an externalist, representational content. I conclude by arguing that a rejection of representationalism does not saddle us with a peculiar qualia view. (shrink)

In this work we present the complex relationship between sound and color in musical creation throughout history that continues to be fruitful in current musical composition. Synesthesia in music establishes a correspondence between sound and color and has been a constant debate since the 17th century. The complex nature of sound appears from ancient Greece in the school of Pythagoras in which the number becomes the configurator of harmony. Since then, different aesthetic attempts have arisen to relate color and (...) sound that reach today's electronic procedures in contemporary music. (shrink)

We can discern two opposing viewpoints regarding synesthesia. According to the first, it is an oddity, an outlier, or a disordered condition. According to the second, synesthesia is pervasive, driving creativity, metaphor, or language itself. Which is it? Ultimately, I favor the first perspective, according to which cross-sensory synesthesia is an outlying condition. But the second perspective is not wholly misguided. My discussion has three lessons. First, synesthesia is just one of a variety of effects in (...) which one sense modality causally impacts and reshapes experience associated with another. These effects are utterly common. However, due to their unfamiliarity, and to their conflict with a widespread conception of the role of the senses in perception and perceptual experience, until recently they have been surprising. Second, synesthesia nevertheless must be distinguished from other inter-modal effects that lead to misperception, such as crossmodal illusions. Third, synesthesia also may be distinguished from the potentially much broader class of synesthetic effects, which could be common across the population and within individuals. (shrink)

Synesthesia is the “union of the senses” whereby two or more of the five senses that are normally experienced separately are involuntarily and automatically joined together in experience. For example, some synesthetes experience a color when they hear a sound or see a letter. In this paper, I examine two cases of synesthesia in light of the notions of “experiential parts” and “conscious unity.” I first provide some background on the unity of consciousness and the question of experiential (...) parts. I then describe two very different cases of synesthesia. Finally, I critically examine the cases in light of two central notions of “unity.” I argue that there is good reason to think that the neural “vehicles” of conscious states are distributed widely and can include multiple modalities. I also argue that some synesthetic experiences do not really enjoy the same “object unity” associated with normal vision. (shrink)

Synesthesia is a phenomenon in which an additional nonstandard perceptual experience occurs consistently in response to ordinary stimulation applied to the same or another modality. Recent studies suggest an important role of semantic representations in the induction of synesthesia. In the present proposal we try to link the empirically grounded theory of sensory-motor contingency and mirror system based embodied simulation to newly discovered cases of swimming-style color synesthesia. In the latter color experiences are evoked only by showing (...) the synesthetes a picture of a swimming person or asking them to think about a given swimming style. Neural mechanisms of mirror systems seem to be involved here. It has been shown that for mirror-sensory synesthesia, such as mirror-touch or mirror-pain synesthesia, concurrent experiences are caused by the overactivity in the mirror neuron system responding to the specific observation. The comparison of different forms of synesthesia has the potential of challenging conventional thinking on this phenomenon and providing a more general, sensory-motor account of synesthesia encompassing cases driven by semantic or emulational rather than pure sensory or motor representations. (shrink)

Encyclopedia entry on color synesthesia with cognitive/neurscientific focus.

Encyclopedia entry on color synesthesia with cognitive/neurscientific focus.

Does synesthesia undermine representationalism? Gregg Rosenberg (2004) argues that it does. On his view, synesthesia illustrates how phenomenal properties can vary independently of representational properties. So, for example, he argues that sound/color synesthetic experiences show that visual experiences do not always represent spatial properties. I will argue that the representationalist can plausibly answer Rosenberg.

The concept of informational encapsulation has been important in promoting a view of the mind that has dominated cognitive science. Multisensory phenomena, such as synaesthesia, have been used as evidence for challenging this view. The main objective of this paper is to provide a more detailed understanding of the nature of such a challenge by examining the two types of grapheme–colour synaesthesia, projectors and associators. It is argued that the phenomena under consideration exemplify partial encapsulation failure and that it is (...) expressed in three forms: intramodal, intermodal, and top-down. Additional support for these claims is provided by considering some evidence on synaesthetic-like experiences in relation to the continuity thesis. (shrink)

Synaesthesia is most often characterised as a union or mixing of the senses. i Richard Cytowic describes it thus: “It denotes the rare capacity to hear colours, taste shapes or experience other equally startling sensory blendings whose quality seems difficult for most of us to imagine” ([1995] 1997, 7). One famous example is of a man who “tasted shapes”. When he experienced flavours he also experienced shapes rubbing against his face or hands. ii Such popular characterisations are rough and ready. (...) What is certainly true about synaesthesia is that it involves the interaction between sensory phenomena: in response to certain stimuli some sensory phenomena are elicited in synaesthetes that are not elicited in non-synaesthetes. However, the exact nature of the additional sensory phenomena forms a large part of the debate on the nature of synaesthesia. Synaesthesia is a condition that has been known about for some time. In the late nineteenth century, and early twentieth, century very many articles appeared on the topic in the psychological literature. iii Much of this work on synaesthesia relied on introspective reports of subjects. In consequence, when later in the twentieth century psychologists eschewed introspective reports and radical behaviourist methodology became the order of the day, synaesthesia was rarely a topic of research. In more recent times, however, psychology has once again changed tack. With the advent of cognitive psychology and of objective techniques that try to probe the nature of conscious states of the mind that are reported in introspection, psychological interest in synaesthesia has resumed. Many new findings about the subject have recently been brought to light. In philosophy, interest in synaesthesia is only just beginning to arise. The phenomenon is potentially philosophically interesting for several reasons.. (shrink)

Synaesthesia is a strange sensory blending: synaesthetes report experiences of colours or tastes associated with particular sounds or words. This volume presents new essays by scientists and philosophers exploring what such cases can tell us about the nature of perception and its boundaries with illusion and imagination.

Synesthetes are people who report having perceptual experiences that are very unusual, such as ?seeing? sounds as colors or ?smelling? colors as odors. It is commonly assumed these days that such synesthetic experiences must be instances of misperceptions. Against this widespread assumption, I will highlight that there is reason to think that at least some synesthetic experiences can be viewed as truly veridical perceptions, and not as illusions or hallucinations. On this view, which I will back up by conceptual arguments (...) and empirical data, synesthesia does sometimes enable the individual to truly pick up on worldly features. In failing to take this possibility on board, the participants in this debate have thus unduly restricted the scope of dialectical options. Finally, the reassessment of synesthetic experiences that I defend in this paper will turn out to have important ramifications not just for synesthesia research, but also for perception theories more generally. (shrink)

Although the condition known as synaesthesia is currently undergoing a scientific resurgence, to date the literature has largely focused on the heterogeneous nature of synaesthesia across individuals. In order to provide a better understanding of synaesthesia, however, general characteristics need to be investigated. Synaesthetic experiences are often described as occurring ‘internally’ or in the ‘mind’s eye’, which is remarkably similar to how we would describe our experience of visual mental imagery. We assessed the role of visual imagery in synaesthesia by (...) sampling a large group of synaesthetes and found that they report experiencing more vivid mental images than controls. These findings have important implications for our general understanding of synaesthesia and, in particular, emphasize the need to control for visual imagery in behavioural and neuroimaging paradigms. (shrink)

A myriad of sensations inform and direct us when we engage with the environment. To understand their influence on the development of our habitus it is important to focus on unifying processes in sensing. This approach allows us to include phenomena that elude a rather narrow view that focuses on each of the five discrete senses in isolation. One of the central questions addressed in this volume is whether there is something like a sensual habitus, and if there is, how (...) it can be defined. This is especially done by exploring the formation and habituation of the senses in and by a culturally shaped habitat. Two key concepts, Synaesthesia and Kinaesthetics, are addressed as essential components for an understanding of the interface of habitat and the rich and multisensory experience of a perceiving subject. At a Berlin-based conference Synaesthesia and Kinaesthetics, scholars from various disciplines gathered to discuss these issues. In bringing together the outcome of these discussions, this book gives new insights into the key phenomena of sensory integration and synaesthetic experiences, it enriches the perspectives on sensually embedded interaction and its habituation, and it expands this interdisciplinary inquiry to questions about the cultures of sensory habitus. (shrink)

This is an encyclopedia entry on Synesthesia. It provides a summary of our current knowledge about the condition and it reviews the philosophical implications that have been drawn from considerations about synesthesia. It's import for debates about consciousness, perception, modular theories of mind, creativity and aesthetics are discussed.

We are sometimes led to a different picture of things when something unexpected occurs which needs explaining. The aim of this thesis is to examine a series of related issues in the philosophy of mind in the light of the unusual condition known to psychologists as ‘synaesthesia’. Although the emphasis will be on the philosophical issues a view of synaesthesia itself will also emerge. Synaesthesia is a distinct type of cross-modal association: stimulation of one sensory modality automatically triggers an additional (...) phenomenal character of experience associated with a second sensory modality in the absence of any direct stimulation of the second modality. Chapter 1 introduces synaesthesia to a philosophical audience by outlining the early history of synaesthesia studies, by summarising contemporary research and by indicating areas of philosophical interest to be considered in the rest of the thesis. Chapter 2 uses synaesthesia to examine one important philosophical model of the mind, Fodor’s modularity hypothesis, and, in turn, investigates the nature of synaesthesia in the light of that model. Fodor claims that cognitive modules can be thought of as belonging to a psychological natural kind in virtue of their possession of most or all of nine specified properties. The most common form of synaesthesia possesses Fodor’s nine specified properties of modularity, and hence it should be understood in terms of an extra cognitive module, and thus as belonging to the abovementioned psychological natural kind. Many psychologists believe that synaesthesia involves a breakdown in modularity. A breakdown in modularity would also explain the apparent presence of the nine specified properties in synaesthesia. I discuss the two concepts of function which underlie the respective theories, defending the breakdown thesis, arguing, in any case, that properties deriving from evolutionary history should also be used to decide between the two theses and thus ultimately membership of a psychological natural kind such as Fodor suggests. The argument is then used to respond to two challenges to the notion of a psychological natural kind. Chapter 3 focuses on the phenomenal character of synaesthetic experience. Externalists about the phenomenal character of experience tend to argue that the character of perceptual experience is to be explained either by the properties objects present to percipients, or by the properties objects are represented by percipients as having. Some internalists argue that there is a need to postulate hrther properties of the individual - in other words, qualia - to account for the individuation of the character of perceptual experience. The existence of additional phenomenal characters of experience in synaesthesia, which cannot directly be explained by reference to features of objects, suggests the existence of extra qualia and thus the presence of qualia in normal perception. The aim of this chapter is to meet the challenge presented by synaesthesia and the extra quaZia argument, and contrariwise, use synaesthesia as a way of fbrther clarifjmg the merits of the respective externalist positions. In the previous chapters the locution of ‘coloured hearing’ will have been adopted. Occasionally the process underlying synaesthesia is described as one of ‘hearing colours’. Chapter 4 rejects the latter usage. In so doing it focuses on the place of synaesthesia vis-a-vis normal perceptual processes. Considerations from previous chapters are further developed in order to shed light both on the metaphysical individuation of perceptual modalities and on how we know the distinctive perceptual modalities. Given the actual content of our concepts of perceptual modalities, it is argued that the actual world is one in which even synaesthetes are unable to hear colours. Consideration is given as to whether there is a possible world in which people could hear colours. The justification of the usage of ‘coloured-hearing’ then leads to a discussion of the relative importance of the individuating conditions of modes of perception. The thesis focuses largely on coloured hearing. What merits the preceding considerations have might be supported if they can be generalised. Chapter 5 goes a small way in that direction. (shrink)

À partir des années 1980 eut lieu une véritable révolution dans la connaissance du phénomène neurologique de la synesthésie, qui s’est accompagnée d’une révolution culturelle avec l’apparition de témoignages personnels de synesthètes. Cette représentation littéraire et plastique des perceptions synesthésiques fait partie du mouvement contemporain de représentations autobiographiques de différentes conditions neurologiques. Carol Steen, Patricia Lynne Duffy et Marcia Smilack sont des acteurs pionniers de la représentation des perceptions synesthésiques. From the 1980s, a revolution took place in the knowledge of (...) the neurological phenomenon of synesthesia, which has been accompanied by a cultural revolution with the emergence of personal accounts of synesthetes. Autobiographical representation—literary or plastic—of synesthetic perceptions belongs to the contemporary movement of autobiographical representations of various neurological conditions. Carol Steen, Patricia Lynne Duffy and Marcia Smilack are pioneers involved in representation of synesthetic perceptions. (shrink)

Wager has argued that synaesthesia provides material for a counterexample to representational theories of the phenomenal character of experience. He gives a series of three cases based on synaesthesia; he requires the second and third cases to bolster the doubtfulness of the first. Here I further endorse the problematic nature of the first case and then show why the other two cases do not save his argument. I claim that whenever synaesthesia is a credible possibility its phenomenal character can be (...) understood in terms of misrepresentation. (shrink)

(1) The induced colours led to perceptual grouping and pop-out, (2) a grapheme rendered invisible through ‘crowding’ or lateral masking induced synaesthetic colours — a form of blindsight — and (3) peripherally presented graphemes did not induce colours even when they were clearly visible. Taken collectively, these and other experiments prove conclusively that synaesthesia is a genuine percep- tual phenomenon, not an effect based on memory associations from childhood or on vague metaphorical speech. We identify different subtypes of number–colour synaesthesia (...) and propose that they are caused by hyperconnectivity between col- our and number areas at different stages in processing; lower synaesthetes may have cross-wiring (or cross-activation) within the fusiform gyrus, whereas higher synaesthetes may have cross-activation in the angular gyrus. This hyperconnec- tivity might be caused by a genetic mutation that causes defective pruning of con- nections between brain maps. The mutation may further be expressed selectively (due to transcription factors) in the fusiform or angular gyri, and this may explain the existence of different forms of synaesthesia. If expressed very diffusely, there may be extensive cross-wiring between brain regions that represent abstract concepts, which would explain the link between creativity, metaphor and synaesthesia (and the higher incidence of synaesthesia among artists and poets). Also, hyperconnectivity between the sensory cortex and amygdala would explain the heightened aversion synaesthetes experience when seeing numbers printed in the ‘wrong’ colour. Lastly, kindling (induced hyperconnectivity in the temporal lobes of temporal lobe epilepsy [TLE] patients) may explain the purported higher incidence of synaesthesia in these patients. We conclude with a synaesthesia-based theory. (shrink)

Synaesthesia is an excellent model for understanding perceptual binding in the human brain. Current evidence suggests that if synaesthetic colour is bound, it is through the same attention-dependent integration of feature maps that occurs in other forms of binding. synaesthetic colour arises after the point that separate wavelengths blend in normal colour vision, which creates a perceptual paradox where synaesthetic and print colour can appear bound to a single location without blending. If a letter is printed in a colour that (...) is different from the synaesthetic colour it induces, the two hues will activate different hue-selective maps allowing for dual representation of colour, but if synaesthetic and print colours are the same/similar they will co-activate the same hue-selective map and create an amplified colour signal. Studies suggest that the parietal cortex plays a key role in this binding of synaesthetic and/or print colour to shape. (shrink)

Synesthesia is occasionally offered as a challenge to Husserl's claims that the sense fields are necessarily distinct. This article demonstrates how synesthesia can be approached through phenomenology. We begin with a review of synesthesia and a brief discussion of how a phenomenological analysis of synesthesia could be productive both for those who experience synesthesia and for phenomenologists. We then shift to analyses of synesthesia through Husserl's notions of association and affectivity, and in light of (...) intersubjective communication. While synesthesia might lead us to think that our individual experiences are unbridgeable, we will find instead that such autonomous experiences are relational and, further, that our different—even incommensurable—experiences are necessarily part of a shared lifeworld. (shrink)

J. A. Gray et al. have recently argued that synaesthesia can be used as a counterexample to functionalism. They provide empirical evidence which they hold supports two anti-functionalist claims: disparate functions share the same types of qualia and the effects of synaesthetic qualia are, contrary to what one would expect from evolutionary considerations, adverse to those functions with which those types of qualia are normally linked. I argue that the empirical evidence they cite does not rule out functionalism, rather the (...) reverse. The fact that the effects of synaesthesia are adverse shows that understanding synaesthetic experiences requires a concept of dysfunction, which in turn presupposes a functionalist account. Such an account, moreover, shows how tokens of the same types of qualia can be associated with different causal histories, thus disarming their first objection. (shrink)

Synaesthesia has an emotional side. Many synaesthetes have a sense of certainty about the reality and accuracy of their experiences. Consequently, when their synaesthesia is mimicked in real life these synaeshtetes report a positive emotion whereas when the opposite is true, they experience discomfort. Synaesthesia can also be induced by emotions, and emotions can also be the synaesthetic experience. Here we review the research on these types of synaesthesia and study the current evidence for the true nature of these emotions (...) associated to synesthetic perceptions as studied in grapheme-colour synaesthesia. We begin by presenting evidence of how they can be measured in a laboratory setting and proceed to report studies showing that emotions are automatically activated and can vary in degree as a function of certain factors. We lastly review a study showing that these emerging emotions can be so strong and vivid that they can influence attitudes towards otherwise neutral stimuli. We conclude by presenting a model that could account for the findings reported here. (shrink)

Synaesthesia's Renaissance comments on attitudes and developments in synaesthesia research during the 20th century, focusing in particular on the last three decades when the greatest change took place. During the last century, reaction to the phenomenon varied by group. Synesthetes were gratified to learn that their experience was bona fide and had a scientific name. Laypersons were fascinated and clamored to know more. Well-known psychologists published on it early in the century, but then academia became hostile. After 1940 synesthesia (...) was dismissed as merely subjective and unsuited to respectable scientific inquiry. For decades critics insisted that synesthesia was neither a real perception nor a brain phenomenon. Though put to rest by century's end, an attitude of disbelief can still be encountered. (shrink)

This chapter distinguishes between two kinds of ordinary multisensory experience that go beyond mere co-consciousness of features (e.g., the experience that results from concurrently hearing a sound in the hallway and seeing the cup on the table). In one case, a sensory experience in one modality creates a perceptual demonstrative to whose referent qualities are attributed in another sensory modality. For example, when you hear someone speak, auditory experience attributes audible qualities to a seen event, a person’s speaking motions. The (...) second kind of multisensory experience attributes features experienced in several sensory modalities to one and the same object via a process of amodal perceptual integration, i.e., integration that occurs separately from processing within the individual sensory modalities. Multisensory experiences arising from holding and seeing a tomato or from seeing the Indian curry boil and smelling it are examples of the second kind of multisensory experience. At the end of the chapter we look at synesthesia, a kind of atypical multisensory experience, and argue that one version of this phenomenon may be able to shed light on the neural mechanism underlying amodally integrated multisensory experience. (shrink)

In this article, we will describe higher order thought theories of consciousness. Then we will describe some examples from synesthesia. Finally, we will explain why the latter may be relevant to the former.

Synaesthesia is considered a rare perceptual capacity, and one that is not capable of cultivation. However, meditators report the experience quite commonly, and in questionnaire surveys, respondents claimed to experience synaesthesia in 35% of meditation retreatants, in 63% of a group of regular meditators, and in 86% of advanced teachers. These rates were significantly higher than in nonmeditator controls, and displayed significant correlations with measures of amount of meditation experience. A review of ancient texts found reports suggestive of synaesthesia in (...) advanced meditators from India and China. These findings suggest that synaesthesia may be cultivated by meditation, and that laboratory studies of meditators could be rewarding. (shrink)

A cognitive-developmental theory of synaesthesias - those subjective states fusing separate perceptual modalities - is supported by research indicating their neocortical basis and first appearance as part of the semantic learning of words, letters, numbers, and time in the early grade school years. It contrasts with models of a primitive, anomalous holdover from an earlier neural hyperconnectivity, widely assumed in recent neuroscience approaches. Classical synaesthesias, occurring most vividly in high 'fantasy proneness' children, as well as the more normative and less (...) stereotyped 'synaesthetic meanings' of mid childhood, would later be internalized as the imagistic side of Vygotsky's 'inner speech' - then introspectable as the typically diffuse felt sense of semantic significance. A synaesthetically structured felt meaning becomes the matrix for the development of metaphoric understanding in later childhood. The further exteriorized development of the full range of synaesthesias in adults high in imaginative absorption and creativity becomes central to the arts, culture, and meditative states of consciousness. This approach overlaps with that of Ramachandran on synaesthesia as a window to the evolution of language and metaphor, but separates the human capacity for cross- modal translation, as the root of all symbol formation, from the full range of synaesthesias that would be its later mid childhood differentiation and adds in the wider adult potential for higher developments of this normally implicit synaesthetic consciousness. (shrink)

Grapheme-colour synaesthesia is a perceptual experience where graphemes, letters or words evoke a specific colour, which are experienced either as spatially coincident with the grapheme inducer (projector sub-type) or elsewhere, perhaps without a definite spatial location (associator sub-type). Here, we address the question of whether synaesthesia can be rapidly produced using a hypnotic colour suggestion to examine the possibility of ‘hypnotic synaesthesia’, i.e. subjectively experienced colour hallucinations similar to those experienced by projector synaesthetes. We assess the efficacy of this intervention (...) using an “embedded figures” test, in which participants are required to detect a shape (e.g., a square) composed of local graphemic elements. For grapheme-colour synaesthetes, better performance on the task has been linked to a higher proportion of graphemes perceived as coloured. We found no performance benefits on this test when using a hypnotic suggestion, as compared to a no-suggestion control condition. The same result was found when participants were separated according to the degree to which they were susceptible to the suggestion (number of coloured trials perceived). However, we found a relationship between accuracy and subjective reports of colour in those participants who reported a large proportion of coloured trials: trials in which the embedded figure was accurately recognised (relative to trials in which it was not) were associated with reports of more intense colours occupying a greater spatial extent. Collectively, this implies that hypnotic colour was only perceived after shape detection rather than aiding in shape detection via colour-based perceptual grouping. The results suggest that hypnotically induced colours are not directly comparable to synaesthetic ones. (shrink)

This review provides a commentary on coloured-hearing arising on hearing music: music-colour synaesthesia. Although traditionally explained by the hyperconnectivity theory (Ramachandran & Hubbard, 2001a) and the disinhibited feedback theory (Grossenbacher & Lovelace, 2001) as a purely perceptual phenomenon, the review of eight coloured-hearing neuroimaging studies shows that it may not be assumed that these explanations are directly translatable to music-colour synaesthesia. The concept of 'ideaesthesia' (Nikolić, 2009) and the role of conceptual and semantic inducers challenge the likelihood of a single (...) mechanism underlying the cause of synaesthesia and argue for a move away from a purely sensory to sensory explanation. Finally, music-colour synaesthesia forms a challenge for established philosophical theories and the position of synaesthesia is considered within the larger context of musical qualia. (shrink)

This chapter provides a review of the hypothesis that synesthetic-like perception is present in infants and toddlers. Infants and very young children exhibit evidence of functional hyperconnectivity between the senses, much of which is reminiscent of the cross-sensory associations observed in synaesthetic adults. As most of these cross-sensory correspondances cannot be easily explained by learning, it is likely that these represent natural associations between the senses. In average adults, these 'natural associations' are felt only intuitively rather than explicitly. These observations (...) have led to the proposal of the 'neonatal synaesthesia hypothesis', which purports that all individuals are born synaesthetic, with explicit conscious perception of these natural cross-modal associations dissipating over development in typical individuals. This dissipation is likely the result of experience-dependent synaptic pruning and/or inhibition of cross-sensory neural connections. At the same time, cross-modal associations matching those common in the environment might be assumed to be learned. This hypothesis is re-evaluated in light of recent research findings, and is examined in the context of current evolutionary models of neuronal recycling and emerging evidence of longitudinal changes in children with synaesthesia. (shrink)

A path-breaking collection launching a new series of books on the senses in antiquity. Synaesthesia and the Ancient Senses presents a radical reappraisal of antiquity's textures, flavours, and aromas, sounds and sights. It offers both a fresh look at society in the ancient world and an opportunity to deepen the reading of classical literature. The book will appeal to readers in classical society and literature, philosophy and cultural history. All Greek and Latin is translated and technical matters are explained for (...) the non-specialist. The introduction sets the ancient senses within the history of aesthetics and the subsequent essays explore the senses throughout the classical period and on to the modern reception of classical literature. (shrink)