Synaesthesia has enjoyed a startling renaissance in the last two decades, and it has been a pleasure for me personally to witness this. As any scholar of this field will know, synaesthesia was a common topic of research at the end of the 19th century and the early part of the 20th century for psychologists and others. Quite why it dwindled from being a phenomenon of considerable scientific interest to one that was virtually lost from science from the 1940s to the 1980s is unclear, and woud make a good question for a historian to delve into. Some have speculated that this was due to the rise of behaviourism, which famously banished subjective self-reporting of mental experience from psychology during these decades. But then why did synaesthesia disappear from science whilst schizophrenia (the symptoms for which are equally dependent on subjective self-report of mental experience) did not?
Whatever the reasons, my colleague Maria Wyke and I were privileged to have the opportunity to test a wonderful painter with synaesthesia, and whose case (E.P) we described in a publication in the journal Perception, in 1987. We felt the least we could do was to either confer some well-deserved respectability to synaesthesia by proving it was real (through a test of genuineness) or seal its fate by banishing it once and for ever more from science, relegating it to a colourful but otherwise unstable, untestable phenomenon. We were more than a little shocked and pleased when the results from this single case amply demonstrated that synaesthesia was real. EP's reports remained highly stable over the period of a year, without any prior warning that she was going to be retested.
As a result of this 'objective' test of synaesthesia (which is really just a test of its consistency over time), other researchers have picked up the phenomenon, which is very heartening. Much of the neuroscience community were won over to recognize the importance of synaesthesia once my colleagues and I (Eraldo Paulesu, Chris Frith, and others) had published an fMRI study. This showed that despite being blindfolded, synaesthetes showed 'visual activity' in the brain when listening to sounds. What clearer validation of their subjective self report did one need? Jeffrey Gray and colleagues in London have recently provided even clearer evidence for this through neuroimaging, in the Journal Nature Neuroscience. How far synaesthesia has come, from being a pariah of science, to being published in Nature.
Julian Asher and I however are currently focused on the ultimate test of its genuineness: finding a gene for synaesthesia. We hope that you, like us, find this topic important, fascinating, and worthy of further research. I wish the Association every success in its aims, and feel it as a great honour to be its Patron.
Professor of Developmental Psychopathology at Cambridge University and founder of the UK Synaesthesia Association.