Synesthesia/Ideasthesia

Synesthesia is a somewhat new and interesting study. Some people have this innate ability to do things a majority of us cannot. Generally speaking, synesthesia is when two sensory sections of the brain are crossed, connected, or blended to which it causes a different kind of enhanced sense. It is an involuntary cognitive pathway. There are some studies that suggest that one can temporarily have moments of synesthetic experiences with the influence of drugs, strokes, seizures, or other cognitive stimulating or inhibiting actions.

For example, some people can taste color or see sound. There are some amazing explanations and different stories given by people who have this ability. Them describing it the best they can sounds phenomenal.  A gift many would like to have. Those who do have it have also talked about how tiring it can be as well as helpful. I would think that one would get a bit of a headache especially in a high sensory area like the city where there is so much commotion. As for being helpful, imagine being able to tell a word is not spelled right because it literally does not look right or being able to listen to the music and you see what the sounds create and sell your artwork?

Ideasthesia is different and yet the same from synesthesia by one difference. Ideasthesia is caused with a somatic sensory connection rather than just the senses. Basically, if we were to have a conversation about something I would be visualizing it in my mind. It then causes me to feel that sensation without actually feeling it. One example used on wiki was swimming. If we were to talk about swimming I might feel wet.

The two subjects are very similar so although they are both very different, I will be referring it to any blending of the senses because of the many categories in synesthesia that can be ideasthesia also.

There appears to be specific kinds of synesthesia. Each one called by which senses they combine

Grapheme which is a color synesthesia.
Spatial sequence synesthesia
Sound related to colors
Number form synesthesia
Personification
Lexical-gustatory synesthesia which is taste and words/letters.

Official Foundations:
American Synesthesia Association
Australian Synesthete Community
UK Synaesthesia Association
Belguin Synesthesia Association
Russian Synesthesia Community Site
Synaisthesis
Synaesthesia

Intriguing People and Media
http://www.ted.com/talks/neil_harbisson_i_listen_to_color.html
http://en.wikipedia.org/wiki/The_Yellow_Sound

Other interesting sites
http://www.mind-expanding-techniques.net/synesthesia.html
History of Synesthesia (Wiki)