What if you could see music, taste colours, or feel the touch of a perfume? This is possible through a neurological condition called "synesthesia." In this episode we talk about how it works, what triggers it, and why it happens. -- Sources: Cytowic RE (2002). Synesthesia: A Union of the Senses. Cambridge, Massachusetts: MIT Press / Rich AN, Mattingley JB (2002): Anomalous perception in synaesthesia: a cognitive neuroscience perspective. Nature Reviews. Neuroscience / Galton F (1880): Visualized Numerals. Nature / Mroczko-Wąsowicz A, Nikolić D (2014): Semantic mechanisms may be responsible for developing synesthesia. Frontiers in Human Neuroscience / Nikolić, D. (2009): Is synaesthesia actually ideaesthesia? An inquiry into the nature of the phenomenon. Proceedings of the Third International Congress on Synaesthesia, Science & Art.