Here is an interesting article on synaesthesia,
http://news.bbc.co.uk/1/hi/sci/tech/8070210.stm
Effectively the “condition/trait” is one of senses being stimulated and giving feedback without external influence (By this I mean in the example shown that moving dots can provide noise to certain subjects)
http://news.bbc.co.uk/1/hi/health/7545888.stm
However, where does the predictive capacity of the mind end and the actual unwarranted inputs begin? Take schizophrenia for instance and the hearing of noises. Take REM dream states and the visualisation, hearing, feeling and all other sensory “experiences” that occurs. What is real?
In my opinion Synaesthesia is the predictive capacity of the mind to automate senses to react to other sensory inputs. For the mind to work quickly it cannot be linear in it approach especially when reaction times in our predatory past have meant the difference between life and death.
Hence, we have assemblages of knowledge which is connective sensory information e.g. visual sharpness automatically creates the bodies awareness for potential sensory tactile pain and so forth. Hence large shapes and deep sounds and so forth are a simple extrapolation and connection to our sensory perception of the world.
Furthermore just as Pavlov’s dogs could be conditioned to salivate when they heard the bell, they could, if salivating; believe they had heard the bell. Such is the minds capacity to fill in the blanks and achieve logical understanding/reasoning.
However, an interesting point is made by Vilayanur Ramachandran
“Processes similar to synaesthesia might also underlie our general capacity for metaphor and be critical to creativity”.
"It is not an accident that the condition is eight times more common among artists than the general population."
Firstly, I would guess that intuitive types are more likely to fit into this category as simply I have already categorised them as more likely to utilise Brodmann area 39 far more to use metaphors in their understanding and interpretations. Effectively a metaphor is the use of an analogy between two objects or ideas. (To add depth and greater perception (Often visualisation) it is necessary to use an analogy).
However, the other aspect I believe is highly relevant is the one of pattern forming and associative connections. Using one sense such as vision various items can be patterned as some logical set (and those with strong pattern forming minds will find some connection not matter how remote). However, there is also pattern forming between senses. The example of the dots moving (In the article link) like a rhythmic heart (pattern visualisation) with the expectation of a beat like a heart (pattern noise), the only difference is those with heighten synaesthesia have that noise registering.
So, in conclusion synaesthesia seems to highlight the minds ability to pattern form across the senses as well as within a sense.
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