On the relative nature of (pitch-based) crossmodal correspondences

This review deals with the question of the relative vs absolute nature of crossmodal correspondences, with a specific focus on those correspondences involving the auditory dimension of pitch. Crossmodal correspondences have been defined as the often-surprising crossmodal associations that people experience between features, attributes, or dimensions of experience in different sensory modalities, when either physically present, or else merely imagined. In the literature, crossmodal correspondences have often been contrasted with synaesthesia in that the former are frequently said to be relative phenomena (e.g., it is the higher-pitched of two sounds that is matched with the smaller of two visual stimuli, say, rather than there being a specific one-to-one crossmodal mapping between a particular pitch of sound and size of object). By contrast, in the case of synaesthesia, the idiosyncratic mapping between inducer and concurrent tends to be absolute (e.g., it is a particular sonic inducer that elicits a specific colour concurrent). However, a closer analysis of the literature soon reveals that the distinction between relative and absolute in the case of crossmodal correspondences may not be as clear-cut as some commentators would have us believe. Furthermore, it is important to note that the relative vs absolute question may receive different answers depending on the particular (class of) correspondence under empirical investigation