Abstract

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