When:
- Black
printed letters or numbers have colour, or a personality, or
- music
is seen in color, or
- days, weeeks or months of the year appear in shapes like
squares, circles and ovals, or
- sounds or words have a taste, or
- tastes have shapes, or
- faces have an aura, or
- sounds have smells or temperature
then synesthesia
appears to be involved. (in fact about half the people experiencing synesthesia have more than one form of
it)
Types of Synesthesia
Most defintions of synesthesia refer to cross
modal sensory experiences. That is experiences where a percept in one sense initiates or co-occurs with a percept in another
sense. This in itself is not uncommon. Scientists are starting to learn that the brain integrates sensory information all
the time. Perhpas the way we see synesthesia will change over time as we understand it more and people discuss it more readily.
Some artists and musicians would argue that we all have some synesthesia (ability to join the senses) but that some people
do it more readily and more permanently than others. Here are some types of synesthesia that have been reported.
One example of this is when you listen to music and you see visual images like colours or shapes. This form of
coloured hearing is called Chromesthesia.
There are however a number of synesthesia types where the percept initiates another class of percept in the same
sense. One example of this is when you see black printed letters or numbers as having a color associated with them. This is
referred to as grapheme / number to color synesthesia.
We are going to look at a few of the different types below.
The
most common form of synesthesia (at least the one most widely studied) is grapheme / number to color. Graphemes (letters of the alphabet) or numbers visually presented in black typeface can initiate
the experience of colour. The synesthetes who experience this often report that the color is superimposed on the letter
in the external environment but many also report seeing the colour in the minds eye. Exactly how these reports
are different is dificult to determine from a scientific and research point of view, but one thing seems likely - these experiences
are perceptually real and not imagined. That is, the synesthetes color experience may utilise similar pathways in the brain
as normal color vision.
There are a number of other types
of synestheisa as well. Ordinal Personification for
example. This is where a number elicits a personality. For example 3 is a young boy eating
ice cream and 8 is his sister.
'Time' to 'Space' correlations
are also reported. Here time units - like days or weeks - are spatially linked to form shapes in external space. Each
person experiences this differently so the shapes can vary from person to person. One research report (Smilek, et al, 2006) reports a subject who sees May as a blue area located on the right area
of her body about an arms length away. Emotion to Color synesthesia
has been reported for individuals who experience colors after thinking about emotional words and
peoples names..
Another common form of
synesthesia is music to color. Many reports of it include
seeing colors from music generated from simple tones or complex musical froms such as songs or instrumental pieces. Some report
that different artists or musical instruments have a particular color associated with them.
Sound to taste synesthesia has also been reported.
(Beeli et al, 2005) In this type of synesthesia a person exeriences a taste sensation when a
partcular tone or sound is presented. Sean Day's website lists a large variety of synesthesia by type and reports the incidence of
each one. It is interesting to see that about half the respondents have more that one type of synesthesia.
