Synesthesia or the curious world of the mixed senses.
“When I’m reading I can see that what I’m looking at is in black and white, but I also see
the ‘correct’ colors for the letters and symbols.”
“I may call someone ‘Debbie’ when she is really ‘Paula’, because D and P are more or less
the same color green.”
“Tuesday is yellow. I don’t ‘see’ it anywhere in particular; rather, I have a general
awareness of yellowness in relation to the word.”
“I avoid middle C when I play the piano, because it has an earthy, musky smell I don’t like.”
These statements were made to scientists by people who were genuinely describing what was going on in their minds. Do they look familiar to you? If so, you may have synesthesia, a condition in which stimulation of one sense evokes the response of a different sense, and that affects 2-4% of the general population.
These experiences are so odd and subjective that, until very recently, doctors and scientists considered that the people who faced them (called synesthetes) were mentally ill, and it was not unusual for them to be diagnosed as schizophrenics and be locked up in mental institutions.
With the advent of more sophisticated methods of research and better insight from scientists, this situation has changed and synesthesia is now widely accepted as normal and it even has the potential to take us closer to understanding how the human brain works. This is because scientists have known for a long time that the brain is divided into different functional areas, which are independent of each other. We are all familiar with cases in which someone suffers brain trauma that leads to loss of one function (i.e. memory, vision, etc) leaving other functions and skills untouched. In other words, it seems that different parts of the brain are self-sufficient and do not normally interact with each other.
Research on synesthesia has allowed scientists to understand this idea better, because brain areas in synesthetes appear to be able to “talk to each other” in a way that non-synesthetes can’t. That unique “skill” is great news for scientists, as it allows them to have a peek at how this unusual talk amongst different parts of the brain occurs.
As is usually the case in science, progress has been slow, and it will take a while before we are aware of how exactly synesthesia occurs and what it teaches us about the brain. Currently, scientists are divided between those who think that
1) Synesthetes have “crossed wires” in the brain (i.e. faulty connections that lead to seeing smells and so forth) or
2) All brain areas are fully connected and in normal people those connections are actively isolated from each other. In synesthetes, some sort of molecular glitch prevents that isolation from happening, and areas of the brain that are normally closed to each other are now in contact. But the main idea here is that the brain structure of synesthetes is not faulty or abnormal.
There are other ideas being proposed by scientists, but they are usually variations or combinations of one of these two.
Regardless of who turns out to be right, it is inspiring that common sense has prevailed and synesthetes don’t have to fear “coming out”. Too often, seemingly odd behaviors or unusual brain skills are associated with stigmas that ruin lives. Some of those stigmas are easier to drop (i.e. it can be “cool” that one can smell music and hear colors); others not so much, as we pointed out earlier for schizophrenia and other disorders.