Synesthesia

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)

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)

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)

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.

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)

This paper provides a categorization of cross-modal experiences. There are myriad forms. Doing so allows us to think clearly about the nature of different cross-modal experiences and allows us to clearly formulate competing hypotheses about the kind of experiences involved in different cross-modal phenomena.

Developmental synesthesia typically involves either the stimulation of one sensory modality which gives rise to an experience in a different modality (when a sound, for example, evokes a colour) or the stimulation of a single sensory modality giving rise to different qualitative aspects of experience (when the sight of a number, for example, evokes a colour). These occurrences seem to support Grice’s (1989) argument that sense modalities cannot be individuated without reference to the introspective-character of experience. This, however, threatens intentionalism (...) which maintains that the qualitative character of experience is exhausted, or fully determined by, its intentional content. Ross (2001) attempts to defuse Grice’s argument by proposing an account that does not appeal to the qualitative character of experience to individuate sense modalities. I argue that his account is unsuccessful. (shrink)

Fodor claims that cognitive modules can be thought of as constituting a psychological natural kind in virtue of their possession of most or all of nine specified properties. The challenge to this considered here comes from synaesthesia. Synaesthesia is a type of cross-modal association: input to one sensory modality reliably generates an additional sensory output that is usually generated by the input to a distinct sensory modality. The most common form of synaesthesia manifests Fodor's nine specified properties of modularity, and (...) hence, according to Segal (1997), it should be understood as involving an extra module. Many psychologists believe that synaesthesia involves a breakdown in modularity. After outlining how both theories can explain the manifestation of the nine alleged properties of modularity in synaesthesia, I discuss the two concepts of function which initially motivate the respective theories. I argue that only a teleological concept of function is properly able to adjudicate between the two theories. The upshot is a further application of so-called externalist considerations to mental phenomena. (shrink)

The Warner Books back cover proclaims: In the tradition of Oliver Sachʼs [sic] bestselling *The Man Who Mistook His Wife for a Hat...* The manner and misspellingsignify that Cytowic himself had nothing to do with such publishing hucksterism. However, one thing is clear upon reading this book: Richard Cytowic, M.D., is no Oliver Sacks. Though, as will be seen, there is much in here to recommend itself, his stilted reproduction of conversations which or may not have taken place and his (...) CreativeFiction 100 characterizations (i.e., Dr. Wood's continual inhalation of smoke or food) strike the experienced reader as painfully contrived, as though Cytowic were doing hislevel best to imitate Sacks and reach that always-elusive wider audience. (shrink)