Abstract

Colour synaesthesia is the mental experience involving a strong association between specific colours and specific auditory stimuli, such as words, or achromatic visual stimuli, such as numerals or letters. In the contemporary literature on colour synaesthesia, the majority view treats the phenomenon as one arising from some of the same neural events mediating colour perception triggered by genuinely coloured objects; this view that synaesthesia is perceptually based, however, is not universally endorsed. What strategies have been utilized to evaluate the perceptual reality of colour synaesthesia, and what is the evidence produced by those strategies? This chapter tackles those questions within the context of colour graphemic synaesthesia, the most widely studied form of synaesthesia. We divide the research strategies into those employing behavioral measures to assess whether synaesthetia influences performance on tasks known to be sensitive stimulus colour and those employing indirect measures that use physiological responses as proxies for colour perception. Our chapter concludes that there is sufficient justification for the belief in the perceptual reality of colour grapheme synaesthesia. At the same time, we applaud those who remain disbelievers, for their skepticism has underscored the logical issues surrounding research on this question.