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Fw: State of the Art: Synaesthesia
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EDNOTE. I have suggested elsewhere that synaesthesia played a part in VN's
creative process. I would also note that the current _Scientific American_
has an excellent article on synaesthesia in which it is suggested that the
rare psychological quick layed a role in the development of meaphore and
language itself.
----- Original Message -----
From: "Nick Grundy" <nick@bsad.org>
> ---------------- Message requiring your approval (337
lines) ------------------
> ----------
> Lovingly typed in from this month's "Psychology".
>
> Interesting section about halfway through, describing where synaesthetes
> have described colour vision appearing - is VN's experience known? To
> anyone looking to skim it, I'd say the paragraphs under the heading "In
the
> brain of a synaesthete" are most interesting, particularly the one on how
> it appears to take place in the part of the brain used in non-synaesthetes
> to comprehend colour patterns. The confusion over whether it operates as
> part of perception, memory, or imagination is also perhaps pertinent, as
> might be the "unanswered question" over whether it is related in some way
> to metaphor in language?
> --------
> What colour is the letter A? What does the number 1 taste of? Does
> listening to music, speaking or eating food produce colours, shapes or
> textures?
>
> For most people, questions such as these will either yield a look of
> bewilderment or an emphatic 'No!' However, when I have posed this
question
> at University College London, as many as 1 per cent are certain that they
> experience something like this. These students may well have synaesthesia.
>
> Synaesthesia is often described as a joining of the senses (Cytowic,
> 1989). Sensations in one modality (e.g. hearing) produce sensations in
> another modality (e.g. colour) as well as in its own. This standard
> description, however, is a simplification, because synaesthetic
experiences
> are often driven by symbolic rather than sensory representations, such as
> letters, numbers, and words. Synaesthesia is also often experienced in the
> absence of external sensory input, such as thinking in colour when doing
> mental arithmetic.
>
> Synaesthesia has been a topic of interest to psychologists ever since
> psychoogy emerged as a discipline in its own right in the late 19th
century
> (e.g. Galton, 1883/1997). It is an intriguing phenomenon because it
> challenges the tacit assumption that other people's perceptual experiences
> of the world are the same as out own.
>
> Philosophers may lose sleep over whether my experience of green is the
same
> as your experience of green, but people on the street do not. This is
> because we can use language as a common currency to agree upon our
> experiences. But what are we to make of someone claiming that the letter A
> is red, when most of us do not experience this at all?
>
> Well, one solution to the problem is to dismiss subjective reports as
> having no place in science or psychology. The behaviourist movement did
> just this, and the number of publications devoted to synaesthesia
plummeted
> in the mid-20th century as a direct result (Harrison, 2001). But times
have
> changed, and understanding how the brain creates our conscious experience
> of the world is a hot topic. Synaesthesia research is enjoying its
> renaissance. But can we really be sure that these subjective reports are
> for real, and what is synaesthesia going to reveal to us about the
workings
> of our own minds?
>
> IN THE MIND OF A SYNAESTHETE
> What is it like to have synaesthesia? The synaesthete Pat Duffy puts it
> this way:
>
> Other people don't see what we see and they're not convinced that we see
it
> ourselves. But what each of us sees is the reality we know. I am at no
more
> liberty to change the white colour of the letter O than I am to change its
> circular shape; for me, the one is a smuch an attribute of the letter as
> the other. (Duffy, 2001, p.4)
>
> The coloured letters on these pages accord to Pat's synaesthetic
alphabet.
> Every synaesthete has their own selection of colours, and often different
> types of trigger. Carol Steen is a synaesthetic artist and describes her
> experience thus:
>
> There have been times when I have had one sensation such as toothache and
> observed the color of the pain, its taste and smell. All these
synaesthetic
> perceptions are aspects of one overall experience. I perceive them as
> related in the same way that windows, a door and front steps combine to
> become the image of a house. (Steen, 2001, p.205)
>
> Carol uses her synaesthetic experiences as inspiration for her artwork.
> 'Vision' [picture present in magazine] shows the colour images that were
> evoked during an acupuncture session. Her desciprtions imply a richness of
> colours, movement and texture:
>
> Lying there, I watched the black background become pierced by a bright red
> colour that began to form in the middle of the rich velvet blackness. The
> red began as a small dot of color and grew quite large rather quickly,
> chasing much of the blackness away. I saw green shapes appear in the midst
> of the red color and move around the red and black fields. (Steen, 2001,
p.205)
>
> As a synaesthetic artist, Carol is in good company. Other famous figures
> with synaesthesia include the painters Wassily Kandinsky and David
Hockney,
> the composer Olivier Messian, and the writer Vladimir Nabokov (Harrison,
> 2001). Kandinsky certainly tried to create a synaesthetic dimension to
> [sic] his work. For example, he wanted his canvases to evoke sounds.
>
> In order to appreciate the diversity of synaesthetic experience, consider
> the answers given to the question 'Where are your synaesthetic
> colours?' Some synaesthetes 'project' their colours onto the stimulus
> itself. Thus, the synaesthetic colours appear in the same location and
> have the same shape as the actual typeface of the letter or word being
> attended to, although they can still report the 'true' colour of the text
> (Ramachandran & Hubbard, 2001). However, most synaesthetes do not report
> seeing their synaesthetic colours in the normal visual field but on an
> inner screen. Consider the following three descriptions in response to the
> question above. Case AD: 'On different "screens", mainly on the inside of
> my forehead.' Case JG: 'They permeate the centre of my brai - a warm
> feeling about 5-8 cm square.' Case KA: '[Coloured] words scroll in from
> right to left, and fade to black at centre screen. They seem to be behind
> my right eye and do not interfere with vision.' The colours occur
> automatically, cannot be suppressed, and pervade almost every aspect of
> mental life. Synaesthetes cannot imagine life without them.
>
> It is not clear why colour is the most common synaesthetic experience, but
> it is (Day, 2002). If it is not triggered by words and letters then it can
> be triggered by music, taste, smells, pains and emotions. Even though it
is
> rarer, synaesthesia can nevertheless be found in every other sensory
> modality. For the last year I have been working with a man, JIW, who
> experiences tastes whenever he hears, reads, speaks or thinks about words
> (Ward & Simner, 2002). The tastes have a subjective location on his tongue
> and in his mouth. The experiences are rich in texture and can even have
> thermal proerties. For example, the word safety tastes of lightly buttered
> toast, and jail is hard, cold bacon. The tastes elicited by particular
> words do not change over time, although the range of tastes exhibited do
to
> some extent reflect his dietary habits. For example, the taste of fish is
> absent from both his synaesthesia and his diet. For JIW, the presence of
> certain tastes can distract him from the content of a conversation, and he
> has to coin nicknames for acquiantances with disagreeably tasting names!
>
> IN THE BRAIN OF A SYNAESTHETE
> What makes some people synaesthetic but not most other people? The answer
> to this question almost certainly lies in the development of the brain
> under the guiding influence of our genes. Synaesthesia runs in families,
> and it may be linked to the X-chromosome (Bailey & Johnson, 1997). It is
> more common in women, and there are no known cases of it being inherited
> from father to son. Intriguingly, the sensory modality that is affected by
> synaesthesia does not seem to be strongly inherited. For example, the
> taste-synaesthetes whom I have studied typically have relatives who
> experience colours or have other types of synaesthesia, and many
> synaesthetes have more than one type. This implies that the hypothetical
> 'synaesthesia gene' may code for something quite general (e.g. degree of
> neural connectivity) rather than an exact phenotype.
>
> The familial segregation of synaesthesia provides some indication that it
> is a geunine phenomenon with a biological origin. It is unclear why
> familial segregation would occur if, say, these people were simply
> remembering coloured alphabet fridge magnets. Empirical studies of
> synaesthetes confirm that synaesthesia is both automatic and perceptual in
> nature. Modern research in the UK was kick-started by a notice placed in
> the Bulletin of the British Psychological Societyin the mid-1980s by a
> synaesthetic artist who was willing to be a research guinea pig. The
> gauntlet was picked up by Simon Baron-Cohen, who took the view that the
> existence of synaesthesia is an empirical question rather than a matter of
> personal opinion. He noted that in this synaesthete, as in others, the
> same stimulus tends to elicit the same percept over time (Baron-Cohen et
> al., 1987). This has been used as a 'test of genuiness' in its own right,
> because one can show that synaesthetes outperform non-synaesthetes who are
> asked to generate colour associations under memory and imagery
> conditions. One can also use the fact that they are consistent to
> construct "Stroop-like" experiments. If a synaesthete experiences the
> letter A as red, then they will be slower at naming the ink colour when it
> is incongruent with their synaesthesia (e.g. when A is printed in green
> ink) than when it is congruent (when A is printed in red ink). In this
> instance their synaesthesia is irrelevant to the task, so the fact that it
> interferes provides strong evidence that it is automatically strong rather
> than strategically elicited (e.g. Mattingley et al., 2001). But the Stroop
> effect does not proves that the phenomenon is perceptual in nature,
because
> it could arise from response competition at an output level.
>
> A recent functional imaging study by Nunn et al. (2002) has provided
strong
> evidence that synaesthesia is perceptual rather than a purely memory
> phenomenon. In their group of synaesthetes, words but not tones evoke
> colour sensations. Brain activity was indeed engendered in the left
> hemisphere colour region (area V4) when listening to words but not tones.
> The left hemisphere lateralisation may reflect the fact that language
> appears to be the inducing stimulus in this group. No such activity was
> found in a non-synaesthetic control group, even when they were trained to
> learn word-colour associations and engaged in colour imagery at retrieval.
> However, when the control group were asked to view coloured patterns, this
> region was activated. Thus, synaesthetic colour perception appears to tap
> the same neural circuitry that, in non-synaesthetic individuals, is used
to
> process colour derived from external visual input. This provides
objective
> support for the synaesthetes' claims that the phenomenon feels more like
> perception than imagination or memory.
>
> ARE WE ALL SYNAESTHETES?
> Most researchers believe that studying synaesthesia could tell us
something
> about the brain and cognition more generally. It is well accepted that
each
> and every one of us engages in cross-modal perception and integration. For
> example, there are neurons in our brain that respond to sensory attributes
> from different modalities - such as colour, taste, and smell. At a
> behavioural level, a series of experiments has shown that when
> non-synaesthetic individuals are asked to make cross-modal matches between
> pitch and colour, then the higher the pitch the lighter the colour (Marks,
> 1982). Interestingly, the same trend is found for synaesthetes who have an
> actual conscious experience of colour in response to music and sounds
> (Marks, 1975). So is synaesthesia just a simple extension of these normal
> cross-modal processes? Possibly, but the final explanation of synaesthesia
> is likely to be more complex, for reasons outlined below.
>
> It is widely acknowledged that synaesthesia can exist in acquired forms,
> and this could be taken as providing supportive evidence for the notion
> that synaesthesia itself reflects an exaggeration of sensory mechanisms
> that we all, to some degree, possess. Certain hallucinogenic drugs, such
as
> mescalin, LSD and psilocybin (from 'magic' mushrooms) can produce
transient
> forms of synaesthesia. Albert Hoffman was the first person to note the
> psychoactive properties of LSD when he accidentally ingested or inhaled
the
> drug. His lab notes from 19 April 1943 clearly describe synaesthesia:
>
> It was particularly striking how acoustic perceptions such as the noise of
> a passing auto, the noise of water gushing from a faucet or the spoken
> word, were transformed into optical illusions. (Hollister, 1968, p.34)
>
> Given that the effects of the drug occus quickly and last a period of
> hours, it is reasonable to assume that they are stimulating existing
> pathways in the brain. The other way of acquiring synaesthesia is through
> sensory deafferentation, such as that arising from progressive blindness
> due to retinal or optic nerve atrophy (e.g. Armel & Ramachandran, 1999).
> These patients may experience colours in response to touch and sounds, as
> well as experiencing spontaneous visual hallucinations (the Charles Bonnet
> syndrome).
>
> The very existence of acquired synaesthesia implies that we all have the
> potential to be synaesthetes in one form or another. However, opinion is
> still divided over whether these acquired forms have any bearing on our
> interpretation and understanding of developmental forms (e.g.
Grossenbacher
> & Lovelace, 2001).
>
> Significant differences between acquired and developmental types of
> synaesthesia certainly do exist. Acquired synaesthesia is most commonly
> triggered by 'simple' sensory stimuli (e.g. pure tones) whilst in
> developmental synaesthesia the eliciting stimulus is often learned
> linguistic material such as letters, numerals, and words. There is no
> evidence to suggest that people can acquire a coloured alphabet such as
Pat
> Duffy's through taking drugs or going blind.
>
> In my opinion, the key difference between acquired and developmental
> synaesthesia may simply lie in the age of onset rather than in the
> underlying mechanisms. In the developmental form the mechanisms which
give
> rise to the synaesthesia are in place before the onset of language
> acquisition, and when the brain itself is immature and malleable. The type
> of synaesthesia exhibited could evolve from the more basic cross-modal
type
> (e.g. pitch-brightness) to those involving speech sounds and eventually
> letters, over a period of time and as a result of experience. There would
> be little, if any, scope for this to occur in the acquired forms, which
> typically occur after language and literacy acquisition and often have
> transient effects. The more basic cross-modal forms may only be found in
> these cases.
>
> There are very few known facts about how synaesthesia develops. But given
> that it tends to run in families, it could be possible to find and stufy
> candidate synaesthetes from an early age, despite the relative rarity of
> the phenomenon. Researchers are, however, finding good evidence to suggest
> that synaesthesia can be influenced by language, context, and the
> environment. Researchers at the University of Waterloo, Ontario, have
shown
> the the colour of an ambiguous grapheme [S / 5 symbol appears in text,
> hereafter denoted by an underscore in this type-up] depends upon
linguistic
> context. When flanked by numerals (e.g. 34_67) then the grapheme takes on
> the colour appropriate for the number 5, but when flanked by letters (e.g.
> MU_IC) it takes on the colour appropriate for the letter S (Myles et al,
in
> press).
>
> My own research with people who experience synaesthetic tastes suggests
> that language can even shape the relationship between the word triggering
> the synaesthesia and the resultant taste (Ward & Simner, 2002). Bizarrely,
> there are often phonetic relationships between the triggering word and the
> name that is used to describe the taste that is elicited. For example,
> cinema may taste of cinnamon rolls, and Chicago may taste of avocado. We
> have observed this in five differnet cases that we are in touch with, and
> have also found similar reports in the early synaesthesia literature
almost
> a hundred years ago (e.g. Ferrari, 1907). The results suggest that
> vocabulary knowledge of food can be used to shape the synaesthetic
> associations. Given that one's vocabulary knowledge and one's diet are
tied
> to experience (the culture one is born into), it suggests a rold of
> environmental influences in synaesthesia that may hitherto have been
> underestimated. Synaesthesia, like so many other psychological phenomena,
> is likely to be an outcome of both nature and nurture.
>
> WHAT IS SYNAESTHESIA RESEARCH GOING TO TELL US?
> State-of-the-art research has shown, beyond reasonable doubt, that
> synaesthesia is a genuine phenomenon in search of an explanation. Previous
> reports of synaesthesia, even by distinguished people such as Galton
> (1883.1997) and Luria (1968) have been subject to scepticism because they
> rely on little more than case descriptions. Establishing that synaesthesia
> is real may seem like a modest achievement, but without it there is no
> foundation for further serious research in this field. It is also of
> fundamental importance to synaesthetes themselves, all of whom are likely
> to have received ridicule and disbelief at some point in their lives.
>
> Now that most psychologists are believers, the hard work is yet to be
done,
> with many unanswered questions remaining (see box opposite), However,
> synaesthesia research is starting to yield some answers to important
> questions in psychology. It is enabling us to disentangle the experiential
> aspects of perception from the more basic sensory mechanisms that normally
> trigger them. Research into synaesthesia has the potential to link
> different levels of explanation from gene to neuron to cognition. It may
> even tell us something about how we, as humans, have evolved language and
> abstract thought that is not normally tied down by our concrete
experiences
> of the world.
>
> [Unanswered questions box] - Why is colour the most common synaesthetic
> experience? - Why do some people experience synaesthetic colours
externally
> in space, but others see them as internal? - Can you have a synaesthetic
> experience wihtout being aware of the stimulus that is triggering it? - In
> what circumstances is synaesthesia an aid or a hindrance? - Can a single
> explanation account for the diversity of synaesthetic phenomena? - How
does
> the putative synaesthesia gene(s) exert influence on the brain? - Do
> metaphors in language have anything to do with synaesthesia? - How does
the
> pattern of synaesthesia change early on in life as a result of
> environmental factors? Dr. Jamie Ward is in the Department of Psychology,
> University College London
>
> ------------
> Typist's note: the Stroop experiments referred to in the article are based
> around a piece of work which showed that printing words which are the
names
> of colours (red, green, blue, yellow) in the wrong colours (i.e. red in
> green lettering, etc.) both slows down ability to name the colour in which
> the word is printed and increases errors. It's used as a classic example
> of interference, and generated some (even?) more interesting follow-up
> pieces of work which demonstrated a link between speed of response and the
> relative meaningfulness (semantic power) of the words. Categories used
> were nonsense syllables ("hjh"), rare words ("eft"), common words
("take"),
> Colour related meanings ("grass"), Colour-names (distant) ("purple"), and
> colour-names (close) ("red"). Most single-step comparisons were
> significant, and all double-step or more comparisons were significant
> beyond the 0.1% level. I take the point in that paragraph to be that
> synaesthesia could be experienced at the same time as visual stimuli -
i.e.
> it is part of the process of perception in the brain and is created either
> on the same mental screen on which we construct the visual field, or that
> it could be experienced when someone is asked to describe what they see,
> i.e. it is a response to activity in the visual field and so happens as a
> result of visual processing rather than concurrently with it.
>
creative process. I would also note that the current _Scientific American_
has an excellent article on synaesthesia in which it is suggested that the
rare psychological quick layed a role in the development of meaphore and
language itself.
----- Original Message -----
From: "Nick Grundy" <nick@bsad.org>
> ---------------- Message requiring your approval (337
lines) ------------------
> ----------
> Lovingly typed in from this month's "Psychology".
>
> Interesting section about halfway through, describing where synaesthetes
> have described colour vision appearing - is VN's experience known? To
> anyone looking to skim it, I'd say the paragraphs under the heading "In
the
> brain of a synaesthete" are most interesting, particularly the one on how
> it appears to take place in the part of the brain used in non-synaesthetes
> to comprehend colour patterns. The confusion over whether it operates as
> part of perception, memory, or imagination is also perhaps pertinent, as
> might be the "unanswered question" over whether it is related in some way
> to metaphor in language?
> --------
> What colour is the letter A? What does the number 1 taste of? Does
> listening to music, speaking or eating food produce colours, shapes or
> textures?
>
> For most people, questions such as these will either yield a look of
> bewilderment or an emphatic 'No!' However, when I have posed this
question
> at University College London, as many as 1 per cent are certain that they
> experience something like this. These students may well have synaesthesia.
>
> Synaesthesia is often described as a joining of the senses (Cytowic,
> 1989). Sensations in one modality (e.g. hearing) produce sensations in
> another modality (e.g. colour) as well as in its own. This standard
> description, however, is a simplification, because synaesthetic
experiences
> are often driven by symbolic rather than sensory representations, such as
> letters, numbers, and words. Synaesthesia is also often experienced in the
> absence of external sensory input, such as thinking in colour when doing
> mental arithmetic.
>
> Synaesthesia has been a topic of interest to psychologists ever since
> psychoogy emerged as a discipline in its own right in the late 19th
century
> (e.g. Galton, 1883/1997). It is an intriguing phenomenon because it
> challenges the tacit assumption that other people's perceptual experiences
> of the world are the same as out own.
>
> Philosophers may lose sleep over whether my experience of green is the
same
> as your experience of green, but people on the street do not. This is
> because we can use language as a common currency to agree upon our
> experiences. But what are we to make of someone claiming that the letter A
> is red, when most of us do not experience this at all?
>
> Well, one solution to the problem is to dismiss subjective reports as
> having no place in science or psychology. The behaviourist movement did
> just this, and the number of publications devoted to synaesthesia
plummeted
> in the mid-20th century as a direct result (Harrison, 2001). But times
have
> changed, and understanding how the brain creates our conscious experience
> of the world is a hot topic. Synaesthesia research is enjoying its
> renaissance. But can we really be sure that these subjective reports are
> for real, and what is synaesthesia going to reveal to us about the
workings
> of our own minds?
>
> IN THE MIND OF A SYNAESTHETE
> What is it like to have synaesthesia? The synaesthete Pat Duffy puts it
> this way:
>
> Other people don't see what we see and they're not convinced that we see
it
> ourselves. But what each of us sees is the reality we know. I am at no
more
> liberty to change the white colour of the letter O than I am to change its
> circular shape; for me, the one is a smuch an attribute of the letter as
> the other. (Duffy, 2001, p.4)
>
> The coloured letters on these pages accord to Pat's synaesthetic
alphabet.
> Every synaesthete has their own selection of colours, and often different
> types of trigger. Carol Steen is a synaesthetic artist and describes her
> experience thus:
>
> There have been times when I have had one sensation such as toothache and
> observed the color of the pain, its taste and smell. All these
synaesthetic
> perceptions are aspects of one overall experience. I perceive them as
> related in the same way that windows, a door and front steps combine to
> become the image of a house. (Steen, 2001, p.205)
>
> Carol uses her synaesthetic experiences as inspiration for her artwork.
> 'Vision' [picture present in magazine] shows the colour images that were
> evoked during an acupuncture session. Her desciprtions imply a richness of
> colours, movement and texture:
>
> Lying there, I watched the black background become pierced by a bright red
> colour that began to form in the middle of the rich velvet blackness. The
> red began as a small dot of color and grew quite large rather quickly,
> chasing much of the blackness away. I saw green shapes appear in the midst
> of the red color and move around the red and black fields. (Steen, 2001,
p.205)
>
> As a synaesthetic artist, Carol is in good company. Other famous figures
> with synaesthesia include the painters Wassily Kandinsky and David
Hockney,
> the composer Olivier Messian, and the writer Vladimir Nabokov (Harrison,
> 2001). Kandinsky certainly tried to create a synaesthetic dimension to
> [sic] his work. For example, he wanted his canvases to evoke sounds.
>
> In order to appreciate the diversity of synaesthetic experience, consider
> the answers given to the question 'Where are your synaesthetic
> colours?' Some synaesthetes 'project' their colours onto the stimulus
> itself. Thus, the synaesthetic colours appear in the same location and
> have the same shape as the actual typeface of the letter or word being
> attended to, although they can still report the 'true' colour of the text
> (Ramachandran & Hubbard, 2001). However, most synaesthetes do not report
> seeing their synaesthetic colours in the normal visual field but on an
> inner screen. Consider the following three descriptions in response to the
> question above. Case AD: 'On different "screens", mainly on the inside of
> my forehead.' Case JG: 'They permeate the centre of my brai - a warm
> feeling about 5-8 cm square.' Case KA: '[Coloured] words scroll in from
> right to left, and fade to black at centre screen. They seem to be behind
> my right eye and do not interfere with vision.' The colours occur
> automatically, cannot be suppressed, and pervade almost every aspect of
> mental life. Synaesthetes cannot imagine life without them.
>
> It is not clear why colour is the most common synaesthetic experience, but
> it is (Day, 2002). If it is not triggered by words and letters then it can
> be triggered by music, taste, smells, pains and emotions. Even though it
is
> rarer, synaesthesia can nevertheless be found in every other sensory
> modality. For the last year I have been working with a man, JIW, who
> experiences tastes whenever he hears, reads, speaks or thinks about words
> (Ward & Simner, 2002). The tastes have a subjective location on his tongue
> and in his mouth. The experiences are rich in texture and can even have
> thermal proerties. For example, the word safety tastes of lightly buttered
> toast, and jail is hard, cold bacon. The tastes elicited by particular
> words do not change over time, although the range of tastes exhibited do
to
> some extent reflect his dietary habits. For example, the taste of fish is
> absent from both his synaesthesia and his diet. For JIW, the presence of
> certain tastes can distract him from the content of a conversation, and he
> has to coin nicknames for acquiantances with disagreeably tasting names!
>
> IN THE BRAIN OF A SYNAESTHETE
> What makes some people synaesthetic but not most other people? The answer
> to this question almost certainly lies in the development of the brain
> under the guiding influence of our genes. Synaesthesia runs in families,
> and it may be linked to the X-chromosome (Bailey & Johnson, 1997). It is
> more common in women, and there are no known cases of it being inherited
> from father to son. Intriguingly, the sensory modality that is affected by
> synaesthesia does not seem to be strongly inherited. For example, the
> taste-synaesthetes whom I have studied typically have relatives who
> experience colours or have other types of synaesthesia, and many
> synaesthetes have more than one type. This implies that the hypothetical
> 'synaesthesia gene' may code for something quite general (e.g. degree of
> neural connectivity) rather than an exact phenotype.
>
> The familial segregation of synaesthesia provides some indication that it
> is a geunine phenomenon with a biological origin. It is unclear why
> familial segregation would occur if, say, these people were simply
> remembering coloured alphabet fridge magnets. Empirical studies of
> synaesthetes confirm that synaesthesia is both automatic and perceptual in
> nature. Modern research in the UK was kick-started by a notice placed in
> the Bulletin of the British Psychological Societyin the mid-1980s by a
> synaesthetic artist who was willing to be a research guinea pig. The
> gauntlet was picked up by Simon Baron-Cohen, who took the view that the
> existence of synaesthesia is an empirical question rather than a matter of
> personal opinion. He noted that in this synaesthete, as in others, the
> same stimulus tends to elicit the same percept over time (Baron-Cohen et
> al., 1987). This has been used as a 'test of genuiness' in its own right,
> because one can show that synaesthetes outperform non-synaesthetes who are
> asked to generate colour associations under memory and imagery
> conditions. One can also use the fact that they are consistent to
> construct "Stroop-like" experiments. If a synaesthete experiences the
> letter A as red, then they will be slower at naming the ink colour when it
> is incongruent with their synaesthesia (e.g. when A is printed in green
> ink) than when it is congruent (when A is printed in red ink). In this
> instance their synaesthesia is irrelevant to the task, so the fact that it
> interferes provides strong evidence that it is automatically strong rather
> than strategically elicited (e.g. Mattingley et al., 2001). But the Stroop
> effect does not proves that the phenomenon is perceptual in nature,
because
> it could arise from response competition at an output level.
>
> A recent functional imaging study by Nunn et al. (2002) has provided
strong
> evidence that synaesthesia is perceptual rather than a purely memory
> phenomenon. In their group of synaesthetes, words but not tones evoke
> colour sensations. Brain activity was indeed engendered in the left
> hemisphere colour region (area V4) when listening to words but not tones.
> The left hemisphere lateralisation may reflect the fact that language
> appears to be the inducing stimulus in this group. No such activity was
> found in a non-synaesthetic control group, even when they were trained to
> learn word-colour associations and engaged in colour imagery at retrieval.
> However, when the control group were asked to view coloured patterns, this
> region was activated. Thus, synaesthetic colour perception appears to tap
> the same neural circuitry that, in non-synaesthetic individuals, is used
to
> process colour derived from external visual input. This provides
objective
> support for the synaesthetes' claims that the phenomenon feels more like
> perception than imagination or memory.
>
> ARE WE ALL SYNAESTHETES?
> Most researchers believe that studying synaesthesia could tell us
something
> about the brain and cognition more generally. It is well accepted that
each
> and every one of us engages in cross-modal perception and integration. For
> example, there are neurons in our brain that respond to sensory attributes
> from different modalities - such as colour, taste, and smell. At a
> behavioural level, a series of experiments has shown that when
> non-synaesthetic individuals are asked to make cross-modal matches between
> pitch and colour, then the higher the pitch the lighter the colour (Marks,
> 1982). Interestingly, the same trend is found for synaesthetes who have an
> actual conscious experience of colour in response to music and sounds
> (Marks, 1975). So is synaesthesia just a simple extension of these normal
> cross-modal processes? Possibly, but the final explanation of synaesthesia
> is likely to be more complex, for reasons outlined below.
>
> It is widely acknowledged that synaesthesia can exist in acquired forms,
> and this could be taken as providing supportive evidence for the notion
> that synaesthesia itself reflects an exaggeration of sensory mechanisms
> that we all, to some degree, possess. Certain hallucinogenic drugs, such
as
> mescalin, LSD and psilocybin (from 'magic' mushrooms) can produce
transient
> forms of synaesthesia. Albert Hoffman was the first person to note the
> psychoactive properties of LSD when he accidentally ingested or inhaled
the
> drug. His lab notes from 19 April 1943 clearly describe synaesthesia:
>
> It was particularly striking how acoustic perceptions such as the noise of
> a passing auto, the noise of water gushing from a faucet or the spoken
> word, were transformed into optical illusions. (Hollister, 1968, p.34)
>
> Given that the effects of the drug occus quickly and last a period of
> hours, it is reasonable to assume that they are stimulating existing
> pathways in the brain. The other way of acquiring synaesthesia is through
> sensory deafferentation, such as that arising from progressive blindness
> due to retinal or optic nerve atrophy (e.g. Armel & Ramachandran, 1999).
> These patients may experience colours in response to touch and sounds, as
> well as experiencing spontaneous visual hallucinations (the Charles Bonnet
> syndrome).
>
> The very existence of acquired synaesthesia implies that we all have the
> potential to be synaesthetes in one form or another. However, opinion is
> still divided over whether these acquired forms have any bearing on our
> interpretation and understanding of developmental forms (e.g.
Grossenbacher
> & Lovelace, 2001).
>
> Significant differences between acquired and developmental types of
> synaesthesia certainly do exist. Acquired synaesthesia is most commonly
> triggered by 'simple' sensory stimuli (e.g. pure tones) whilst in
> developmental synaesthesia the eliciting stimulus is often learned
> linguistic material such as letters, numerals, and words. There is no
> evidence to suggest that people can acquire a coloured alphabet such as
Pat
> Duffy's through taking drugs or going blind.
>
> In my opinion, the key difference between acquired and developmental
> synaesthesia may simply lie in the age of onset rather than in the
> underlying mechanisms. In the developmental form the mechanisms which
give
> rise to the synaesthesia are in place before the onset of language
> acquisition, and when the brain itself is immature and malleable. The type
> of synaesthesia exhibited could evolve from the more basic cross-modal
type
> (e.g. pitch-brightness) to those involving speech sounds and eventually
> letters, over a period of time and as a result of experience. There would
> be little, if any, scope for this to occur in the acquired forms, which
> typically occur after language and literacy acquisition and often have
> transient effects. The more basic cross-modal forms may only be found in
> these cases.
>
> There are very few known facts about how synaesthesia develops. But given
> that it tends to run in families, it could be possible to find and stufy
> candidate synaesthetes from an early age, despite the relative rarity of
> the phenomenon. Researchers are, however, finding good evidence to suggest
> that synaesthesia can be influenced by language, context, and the
> environment. Researchers at the University of Waterloo, Ontario, have
shown
> the the colour of an ambiguous grapheme [S / 5 symbol appears in text,
> hereafter denoted by an underscore in this type-up] depends upon
linguistic
> context. When flanked by numerals (e.g. 34_67) then the grapheme takes on
> the colour appropriate for the number 5, but when flanked by letters (e.g.
> MU_IC) it takes on the colour appropriate for the letter S (Myles et al,
in
> press).
>
> My own research with people who experience synaesthetic tastes suggests
> that language can even shape the relationship between the word triggering
> the synaesthesia and the resultant taste (Ward & Simner, 2002). Bizarrely,
> there are often phonetic relationships between the triggering word and the
> name that is used to describe the taste that is elicited. For example,
> cinema may taste of cinnamon rolls, and Chicago may taste of avocado. We
> have observed this in five differnet cases that we are in touch with, and
> have also found similar reports in the early synaesthesia literature
almost
> a hundred years ago (e.g. Ferrari, 1907). The results suggest that
> vocabulary knowledge of food can be used to shape the synaesthetic
> associations. Given that one's vocabulary knowledge and one's diet are
tied
> to experience (the culture one is born into), it suggests a rold of
> environmental influences in synaesthesia that may hitherto have been
> underestimated. Synaesthesia, like so many other psychological phenomena,
> is likely to be an outcome of both nature and nurture.
>
> WHAT IS SYNAESTHESIA RESEARCH GOING TO TELL US?
> State-of-the-art research has shown, beyond reasonable doubt, that
> synaesthesia is a genuine phenomenon in search of an explanation. Previous
> reports of synaesthesia, even by distinguished people such as Galton
> (1883.1997) and Luria (1968) have been subject to scepticism because they
> rely on little more than case descriptions. Establishing that synaesthesia
> is real may seem like a modest achievement, but without it there is no
> foundation for further serious research in this field. It is also of
> fundamental importance to synaesthetes themselves, all of whom are likely
> to have received ridicule and disbelief at some point in their lives.
>
> Now that most psychologists are believers, the hard work is yet to be
done,
> with many unanswered questions remaining (see box opposite), However,
> synaesthesia research is starting to yield some answers to important
> questions in psychology. It is enabling us to disentangle the experiential
> aspects of perception from the more basic sensory mechanisms that normally
> trigger them. Research into synaesthesia has the potential to link
> different levels of explanation from gene to neuron to cognition. It may
> even tell us something about how we, as humans, have evolved language and
> abstract thought that is not normally tied down by our concrete
experiences
> of the world.
>
> [Unanswered questions box] - Why is colour the most common synaesthetic
> experience? - Why do some people experience synaesthetic colours
externally
> in space, but others see them as internal? - Can you have a synaesthetic
> experience wihtout being aware of the stimulus that is triggering it? - In
> what circumstances is synaesthesia an aid or a hindrance? - Can a single
> explanation account for the diversity of synaesthetic phenomena? - How
does
> the putative synaesthesia gene(s) exert influence on the brain? - Do
> metaphors in language have anything to do with synaesthesia? - How does
the
> pattern of synaesthesia change early on in life as a result of
> environmental factors? Dr. Jamie Ward is in the Department of Psychology,
> University College London
>
> ------------
> Typist's note: the Stroop experiments referred to in the article are based
> around a piece of work which showed that printing words which are the
names
> of colours (red, green, blue, yellow) in the wrong colours (i.e. red in
> green lettering, etc.) both slows down ability to name the colour in which
> the word is printed and increases errors. It's used as a classic example
> of interference, and generated some (even?) more interesting follow-up
> pieces of work which demonstrated a link between speed of response and the
> relative meaningfulness (semantic power) of the words. Categories used
> were nonsense syllables ("hjh"), rare words ("eft"), common words
("take"),
> Colour related meanings ("grass"), Colour-names (distant) ("purple"), and
> colour-names (close) ("red"). Most single-step comparisons were
> significant, and all double-step or more comparisons were significant
> beyond the 0.1% level. I take the point in that paragraph to be that
> synaesthesia could be experienced at the same time as visual stimuli -
i.e.
> it is part of the process of perception in the brain and is created either
> on the same mental screen on which we construct the visual field, or that
> it could be experienced when someone is asked to describe what they see,
> i.e. it is a response to activity in the visual field and so happens as a
> result of visual processing rather than concurrently with it.
>