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Binding and hyperbinding in intermodal perception and synesthesia
Abstract
When humans perceive an object, their perceptory organs transform the properties of the object into percepts of different modalities, which are then related with one another in such a way that the object appears as a unified entity in consciousness. This neurobiological process, which is still largely unknown, is called "binding". When during the perception process a given percept is combined with an additional percept which arises in a different modality without being directly based on a property of the perceived object, one speaks of "synesthesia". In coloured hearing, e.g., acoustic properties of an object are simultaneously perceived visually. This process is called "hyperbinding". The present article argues that binding and hyperbinding have the same neurophysiological basis. The utilization of the process configuration characteristic for hyperbinding as a research model for the investigation of binding is proposed.
An issue "milieu research" in the Journal of Semiotics requires justification. This article focuses on demonstrating how institutional criticism within social Psychiatry and the related objects of social psychiatric milieu research can be discussed as part of a semiotic theory of culture which deals with notions such as "institution", "code", "communication", and "aesthetic experience". In this sense, social psychiatry has indeed always been related to cultural theory, in particular to a phenomenologically and hermeneutically grounded theory of "sense". However, approaches embedding empirical research efforts into a general theory of signs are still rare.
In a small proportion of the normal population, stimulation in one modality can lead to perceptual experience in another, a phenomenon known as synaesthesia. In the most common form of synaesthesia, hearing a word can result in the experience of colour. We have used the technique of PET, which detects brain activity as changes of regional cerebral blood flow (rCBF), to study the physiology of colour-word synaesthesia in a group of six synaesthete women. During rCBF measurements synaesthetes and six controls were blindfolded and were presented with spoken words or pure tones. Auditory word, but not tone, stimulation triggered synaesthesia in synaesthetes. In both groups word stimulation compared with tone stimulation activated the classical language areas of the perisylvian regions. In synaesthetes, a number of additional visual associative areas, including the posterior inferior temporal cortex and the parieto-occipital junctions, were activated. The former has been implicated in the integration of colour with shape and in verbal tasks which require attention to visual features of objects to which words refer. Synaesthetes also showed activations in the right prefrontal cortex, insula and superior temporal gyrus. By contrast, no significant activity was detected in relatively lower visual areas, including areas V1, V2 and V4. These results suggest that colour-word synaesthesia may result from the activity of brain areas concerned with language and visual feature integration. In the case of colour-word synaesthesia, conscious visual experience appears to occur without activation of the primary visual cortex.