Abstract

Weak synesthesia refers to the recognition of similarities or correspondences across different domains of sensory, affective, or cognitive experience - for example, the similarity between increasingly high-pitched sounds and increasingly bright lights. Strong synesthesia, in contrast, refers to the actual arousal of experiences in another domain, as when musical notes evoke colors. Whereas various forms of strong synesthesia characterize mental life in a relatively small portion of population, weak synesthesia is far more pervasive, in some instances virtually universal. Several examples of cross-modal similarity, such as pitch-brightness, appear in early childhood, even infancy, consistent with the hypothesis that they are intrinsic to sensory processing, although even early cross-modal similarities might be learned through exposure to correlated sensory events. Beyond perception, weak synesthesia reveals itself notably the production and understanding of cross-modal metaphors, found in both everyday and literary language. The comprehension of synesthetic metaphors by both children and adults often parallels cross-modal similarities in perception. It is likely that, whatever their source, many cross-modal similarities, perhaps most of them, begin in perception and then become available to language. The evidence that preschool-aged children can perceive cross-sensory resemblances and comprehend cross-sensory metaphors is consistent with the hypothesis that mechanisms underlying weak synesthesia play a significant role in the ontogeny of metaphor comprehension and metaphor creation more generally. Theories of embodied cognition, which treat mind as embedded in body and bodily action, may provide a useful framework for understanding metaphor in general and synesthetic metaphor in particular.