Abstract

Until relatively recently, researchers believed that synaesthetic sensations and their triggers were arbitrarily paired, and entirely idiosyncratic from one synaesthete to the next. Put differently, they believed that no two synaesthetes would have similar experiences from the same set of triggers, unless this had occurred by chance. This position likely arose because, prior to the internet, it was extremely difficult to recruit more than a small handful of synaesthete participants, and on the surface, synaesthetes do tend to disagree on their associations when compared one-on-one. However, recent advances in communication have allowed researchers access to far larger groups of synaesthete participants, and this has changed our opinion about how similar synaesthetes might in fact be. A dedicated body of research has now shown that synaesthetic associations are built, to some extent, on a set of unconscious 'rules', shared across synaesthetes. These rules dictate the choice of sensation for certain triggers, and allow us to see patterns emerging which, although not absolute, provide a type of coherence across synaesthetes as a whole. I shall also show that some of these underlying rules operate in the population at large, to allow all individuals to make intuitive pairings across the senses. This chapter describes some of these rules, across a range of different modalities, and across different variants of synaesthesia.