Linguistic synesthesias combine different senses, as in English smooth melody (touchsound). For nearly a century, researchers have gathered data that has been interpreted as supporting the notion of a hierarchical ordering of the senses. According to this proposal, expressions map the presumed-to-be 'lower' senses of touch, taste, and smell onto the presumed-to-be 'higher' senses of sound and sight. Here, this proposal is tested in the first-ever meta-analysis of linguistic synesthesias, combining thirty-eight datasets from fourteen different languages. The authors demonstrate that clear patterns emerge from the data, but many such patterns are inconsistent with the notion of a linear hierarchical order or a simple lower/higher divide of the senses. This calls for a shift in what theories are considered to be viable for explaining asymmetries between the senses in linguistic synesthesia.
