We begin this chapter with a review of the history of synaesthesia and a comparison of what we consider to be either genuine or inauthentic manifestations of the phenomenon. Next, we describe the creation and development of synaesthetic consistency tests and explore reasons why assessing consistency became the most widely used method of confirming the genuineness of synaesthesia. We then consider methodologies that demonstrate synaesthesia's authenticity by capitalizing on properties other than consistency. Finally, we discuss how together, consistency tests and (...) other methodologies are helping researchers determine prevalence and elucidate the mechanisms of synaesthesia. (shrink)