The Induction of Synaesthesia in Non-Synaesthetes

In this chapter we review research examining the induction of synaesthesia with training, posthypnotic suggestion, and pharmacological agents in non-synaesthetes. Each of these methods has been shown to produce different aspects of synaesthesia, but none have produced experiences that have been corroborated using neuroimaging assays. Nevertheless, the close parallels between induced and congenital synaesthesias have the potential to illuminate different facets of this condition. We argue that training may be a valuable model for studying the learning mechanisms underlying congenital synaesthesia, posthypnotic suggestion may have greater utility in the experimental manipulation of this condition, and the administration of pharmacological agents may serve as a useful tool for studying the development of synaesthesia or for large-scale studies of induced synaesthesia. Induced synaesthesias also raise important questions regarding espoused criteria for demarcating synaesthesia from other phenomena.