Synaesthetic consistency spans decades in a lexical-gustatory synaesthete.

Developmental synaesthesia is typically characterised by the consistency of synaesthetic pairings, in that stimuli tend to generate the same synaesthetic responses over time (e.g., if A is red, it is always red). Although studies have illustrated consistency over many months and even several years, little is known about the longevity of reports outside the practical time-constraints of laboratory testing. Here we provide the first objective empirical evidence of synaesthetic consistency spanning from the 1970s to the current day (27 years) and use this longevity to identify the likely roots of such cross-modal associations.