We think of synaesthesia as an unusual sensory effect – the senses getting ‘mixed up’. But it may be more accurate to think of it as a ‘mix up’ in the binding of qualia to concepts. D. Nikolic, U. Jurgens, N. Rothen, B. Meier and A. Mroczko published a paper in Cortex, Swimming-style synesthesia (2011) that shows a clear concept component. I have not found free access to this paper but here is the abstract:

The traditional and predominant understanding of synesthesia is that a sensory input in one modality (inducer) elicits sensory experiences in another modality (concurrent). Recent evidence suggests an important role of semantic representations of inducers. We report here the cases of two synesthetes, experienced swimmers, for whom each swimming style evokes another synesthetic color. Importantly, synesthesia is evoked also in the absence of direct sensory stimulation, i.e. the proprioceptive inputs during swimming. To evoke synesthetic colors, it is sufficient to evoke the concept of a given swimming style e.g., by showing a photograph of a swimming person. A color-consistency test and a Stroop-type test indicated that the synesthesia is genuine. These findings imply that synesthetic inducers do not operate at a sensory level but instead, at the semantic level at which concepts are evoked. Hence, the inducers are not defined by the modality-dependent sensations but by the “ideas” activated by these sensations.

It would be interesting to find out if this effect is operating just at a semantic level or whether, as I suspect, it acts at a more general conceptual level. Can it happen with concepts that do not have associated name-words?