Synesthesia

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)

Despite the recent surge in research on, and interest in, synesthesia, the mechanism underlying this condition is still unknown. Feedforward mechanisms involving overlapping receptive fields of sensory neurons as well as feedback mechanisms involving a lack of signal disinhibition have been proposed. Here I show that a broad range of studies of developmental synesthesia indicate that the mechanism underlying the phenomenon may involve reinstatement of brain activity in different sensory or cognitive streams in a way that is similar to what (...) happens during memory retrieval of semantically associated items. In the paper’s final sections I look at the relevance of synesthesia research, given the memory model, to our understanding of multisensory perception and common mapping patterns. (shrink)

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)

The basis of perception is the processing and categorization of perceptual stimuli from the environment. Much progress has been made in the science of perceptual categorization. Yet there is still no consensus on how the brain generates sensory individuals, from sensory input and perceptual categories in memory. This chapter argues that perceptual categorization is highly variable across perceivers due to their use of different perceptual strategies for solving perceptual problems they encounter, and that the perceptual system structurally adjusts to the (...) strategies that are most successful. Despite this variability, the different sensory individuals that result when different perceivers rely on different strategies nonetheless correspond to actual external world objects/features. This view is called 'perceptual pluralism'. (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)

We ran a pilot experiment to explore, using a new psychophysical method, the hypothesis proposed by Zietz and Werner in the ’30s, that a sound presented simultaneously with an afterimage can change its phenomenal appearance in non-synaesthetes. The method we adopted is able to directly collect and visualise the apparent changes in intensity of the afterimages, by recording observers’ interactions with a physical feedback mechanism, without referring to verbal descriptions. These first findings support some of the most meaningful observations reported (...) by Werner and Zietz, according to which the colours of the afterimages ‘disintegrate’ at the hearing of a low sound and ‘concentrate’ for a high sound. This relationship is particularly evident with the Yellow stimulus, where the perceived colour intensity of its afterimage seems to have a faster negative change with a low-pitched tone sound, and an increase in intensity and duration when perceived simultaneously with a soprano sound. These data are also coherent with the crossmodal correspondences between both pitch and loudness in audition and lightness and brightness in vision reported in the literature. (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)

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)

This article takes as its focus the concept of the ‘afterimage’ and its relationship to memory, the synaesthetic experience of perception and the multisensory turn within the study of photographic images. Afterimages have consistently been described as phenomena of visual persistence where, optically, a recorded moment of the past leaks into the present and remains visible before us on our retinas. By recasting this originary understanding of an afterimage as simply a ghostly, optical occurrence and insisting that the phenomenon exceeds (...) the visual and is rather an intersensorial occurrence, I seek to present how encounters with images stay with us in powerful ways and across many senses at once. As an intervention within the field of image theory and photography studies that builds upon the relatively recent turn away from prioritizing visuality and instead shifting towards multisensoriality – what we might also term as the ‘more-than visual’ – this piece proposes that if images exceed the visual and carry with them physical, haptic, sonic and affective qualities, then perhaps the afterimage is not something that we merely see but also what we can feel and hear and move-with. Perhaps the afterimage carries an intensity and an afterlife which lingers in our minds and can take hold of our entire body and our senses, composing and recomposing them over time. By pairing such inquiries alongside the narrative, literary and poetic works of Dionne Brand and Nathaniel Mackey – both of whom write of the intersensorial quality of photographs and afterimages with a particular kind of lively openness – I am hoping to intervene into the ongoing ‘more-than visual’ turn within the field of image theory by infusing it with a narrative-oriented synaesthetic vocabulary. (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)

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)

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)

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)

This thesis has, as its primary target, the neo-cartesianism, or property dualism of certain philosophers of mind: David Chalmers, Tim Bayne, and others. All begin with a pre-theoretic commitment to the view that all perceptual states are conscious. They define consciousness by saying that it is synonymous with having ‘qualia’ – a term directed at phenomenal properties which defy reduction to physical states. The thesis argues that this position is challenged by certain neurological conditions, - blindsight, visual form agnosia etc- (...) which we can generalise as ‘dissociations’: conditions in which functions are separated from awareness. The thesis holds that these are examples of unconscious perception, which present the case for a different pre-theoretic position, and a redefinition of concepts used in the vicinity. Insofar as the neo-cartesians recognise the empirical, their inclination to reject the dissociations is challenged with new cases and paradigms which have emerged in recent years. It is contended that the dissociations disrupt Chalmers’ coherence between the phenomenal and the psychological, Bayne’s commitment to the Unity of Consciousness, and Phillips’ campaign against unconscious perception. In addition, synaesthesia is advanced as a problem case for Bayne’s unity contention. I argue that the dissociations are not easily dismissed, and present a real challenge for neo-cartesianism. In exploring this challenge, the thesis contributes to the case for a different philosophy of mind – a Higher Order Thought approach. The notion of unconscious perception – it is contended - much more easily finds an accommodation in HOT theories, so this thesis contributes to existing arguments for that position. HOT theories also have an advantage in being receptive to reduction, in giving a developmental account of consciousness, and in being more open to the accommodation of empirical discoveries. In each respect, there is an advantage over the respective positions taken by Chalmers and Bayne. (shrink)

We often use terms primarily concerned with the description of inanimate objects in order to characterize psychological states or dispositions, without being able to specify the connection between the two uses. I call this inanimation. In this paper, I propose an account of inanimation and of its connection to expressiveness.

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)

What do different concepts like true lie, bad luck, honest thief, old news, spacetime, glocalisation, symplexity, sustainable development, constant change, soft law, substantive due process, pure law, bureaucratic efficiency and global justice have in common? What connections do they share with innumerable paradoxes, like the ones of happiness, of time, globalisation, sex, and of free will and fate? Law in the Time of Oxymora provides answers to these conundrums by critically comparing the apparent rise in recent years of the use (...) of rhetorical figures called "essentially oxymoronic concepts" in the areas of art, science and law. Albeit to varying degrees, these concepts share the quality of giving expression to apparent contradictions. Through this quality, they also challenge the scientific paradigm rooted in the dualist thinking and binary logic that is traditionally used in the West, as opposed to the East, where a paradoxical mode of thinking and fuzzy logic are said to have been cultivated. Following a review of oxymora and paradoxes in art and various scientific writings, hundreds of 'hard cases' featuring oxymora and a comprehensive review of the legal literature are discussed, revealing evidence suggesting that the present scientific paradigm of dualism alone will no longer be able to tackle the challenges arising from increasing diversity and complexity coupled with an apparent acceleration of change. Law in the Time of Oxymora reaches the surprising conclusion that essentially oxymoronic concepts may inaugurate a new era of cognition involving the ways the senses interact and how we reason, think and make decisions in law and in life. (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.

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 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)

Studies have shown that both serotonin and glutamate receptor systems play a crucial role in the mechanisms underlying drug-induced synesthesia. The specific nature of these mechanisms, however, continues to remain elusive. Here we propose two distinct hypotheses for how synesthesia triggered by hallucinogens in the serotonin-agonist family may occur. One hypothesis is that the drug-induced destabilization of thalamic projections via GABAergic neuronal circuits from sensory areas leads to a disruption of low-level, spontaneous integration of multisensory stimuli. This sort of integration (...) regularly occurs when spatial and temporal attributes match. Destabilization of feedback loops, however, can result in incongruent experiences or binding of random thalamus activation with sensory input in a particular sensory modality. The second hypothesis builds on embodied cognition, cases in which visual images of external stimuli activate task-related neural regions. On this proposal, binding processes that do not normally generate awareness become accessible to consciousness as a result of decreased attentional discrimination among incoming stimuli. (shrink)

In response to Fred Adams and Charlotte Shreve’s (2016) paper entitled “What Can Synesthesia Teach Us about Higher Order Theories of Consciousness?”, previously published in Symposion, I argue that H.O.T. theory does have the resources to account for synesthesia and the specific worries that they advance in their paper, such as the relationship between concepts and experience and the ability to handle instances of ‘pop-out’ experiences.

The phenomenon of synesthesia has undergone an invigoration of research interest and empirical progress over the past decade. Studies investigating the cognitive mechanisms underlying synesthesia have yielded insight into neural processes behind such cognitive operations as attention, memory, spatial phenomenology and inter-modal processes. However, the structural and functional mechanisms underlying synesthesia still remain contentious and hypothetical. The first section of the present paper reviews recent research on grapheme-color synesthesia, one of the most common forms of synesthesia, and addresses the ongoing (...) debate concerning the role of selective attention in eliciting synesthetic experience. Drawing on conclusions of the first half, the paper’s second half examines the various models proposed to explain the cognitive mechanisms behind grapheme-color synesthesia, and discusses the explanatory virtues of a new model suggesting that grapheme-color synesthesia is grounded in memory. The last section offers an examination of some of the broader philosophical implications of synesthesia. (shrink)

Grapheme-colour synaesthetes experience unusual colour percepts when they encounter letters and/or digits. Studies of English-speaking grapheme-colour synaesthetes have shown that synaesthetic colours are sometimes triggered by rule-based linguistic mechanisms . In contrast, little is known about synaesthesia in logographic languages such as Chinese. The current study shows the mechanisms by which synaesthetic speakers of Chinese colour their language. One hypothesis is that Chinese characters might be coloured by their constituent morphological units, known as radicals, and we tested this by eliciting (...) synaesthetic colours for characters while manipulating features of the radicals within them. We found that both the function and position of radicals influence the nature of the synaesthetic colour generated. Our data show that in Chinese, as in English, synaesthetic colours are influenced by systematic rules, rather than by random associations, and that these rules are based on existing psycholinguistic mechanisms of language processing. (shrink)