Synaesthesia is a neurological condition in which people make unusual associations between various sensations. In recent years, a number of non-developmental cases, including posthypnotic suggestion, drug-use, flavor perception, and use of sensory substitution devices have been linked or directly associated to the emergence of particular types of synaesthetic experiences. Our aim in this chapter is to investigate the extent to which the abovementioned borderline cases can be counted as genuine synesthetic experiences. To do so, we first discuss a number of criteria (i.e., inducer-concurrent pairing, idiosyncrasy, consistency over time, and automaticity of the process) that has been taken as definitional aspects of the condition. We subsequently investigate whether those non-developmental cases fulfill these criteria. Drawing on the lessons learned from the analysis of the borderline cases; we finally highlight the implications of their inclusion on the unity or plurality of the condition.
Available at: http://works.bepress.com/mirko_farina/15/