The
earliest written record of synaesthesia is widely attributed to a
John Locke essay on published in 1690. So, although the medical
profession has been aware of synaesthesia for quite some time, there still
as yet doesn't appear to be an official, established method of diagnosing
synaesthesia. Although I do believe work has been going on in the
U.S.
to at least establish rough guidelines for diagnostic purposes.
The
medical profession do appear to agree that synaesthesia is a natural state
of being experienced by everyone as an infant, but dies away as we mature.
For whatever reason, some of us have retained these pre-infancy links.
Researchers also suggest that the synaesthesia experience is an addition
to our basic major senses and doesn't replace or impair any of them.
Many
researchers are keen to study synaesthesia because they believe it could
tell them more about human consciousness and the way in which we perceive
our world.