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This article supplements our earlier paper on synaesthesia published in JCS (Ramachandran & Hubbard, 2001a). We discuss the phenomenology of synaesthesia in greater detail, raise several new questions that have emerged from recent studies, and suggest some tentative answers to these questions.
V.S. Ramachandran and E.M. Hubbard
The Phenomenology of Synaesthesia
Abstract: This article supplements our earlier paper on synaesthesia published
in JCS (Ramachandran & Hubbard, 2001a). We discuss the phenomenology of
synaesthesia in greater detail, raise several new questions that have emerged
from recent studies, and suggest some tentative answers to these questions.
I: Robustness of Synaesthetic Effects
It was Francis Galton (1880) who first reported the condition called
synaesthesia. He noticed that a certain number of people in the general popula-
tion, who are otherwise completely normal, seemed to have a certain peculiarity:
they experience sensations in multiple modalities in response to stimulation of
one modality. For example, musical notes might evoke distinct colours; F#might
be red and C#blue. Or the printed number 5 always ‘looks’ green, whereas 2
looks red.
Recent evidence suggest that synaesthesia is a genuine sensory phenomenon,
not a high-level memory association (Ramachandran & Hubbard, 2001a,b). This
raises several new questions regarding the robustness of the colours evoked by
specific graphemes. Do physical changes in the number affect the perceived col-
our? And, to what extent are the grapheme–colour correspondences universal,
i.e., seen in a majority of synaesthetes?
(a) Does it matter whether the letters are upper or lower case?
We usually find that upper and lower case letters evoke the same colours,
although the lower case letters were usually less saturated, or were ‘shiny’ or
‘patchy’ compared to the upper case letter, perhaps because upper case is learnt
earlier. There are exceptions to this. For example, in ‘Sarah’ most letters fol-
lowed the rule, but E had completely different colours for upper and lower case
(‘E’ was green, while ‘e’ was red).
(b) Does the font of the number or letter affect the colours?
Prototypical fonts like Times Roman or Arial normally give the most vivid col-
our for that letter, but on occasion a ‘weird’ font like Gothic actually evokes a
stronger colour. We suggest that such fonts might serve as ‘hyper-normal’stimuli
Journal of Consciousness Studies,10, No. 8, 2003, pp. 49–57
Correspondence: Center Brain and Cognition, University of California, San Diego, 9500 Gilman
Drive, La Jolla, CA 92093-0109, USA. Email:
that evoke even larger responses from the grapheme neurons than a more
‘prototypical’ font might. This would be an example of the peak-shift effect,
which causes seagull chicks actually to prefer pecking at a long stick with three
stripes to pecking at a real beak (see Ramachandran & Hirstein, 1999).
(c) What if the number is presented in the ‘wrong’ colour?
This produces a slight delay in naming the colour; the induced colour delays the
ability to report the real colour. This effect — Stroop interference — shows that
the colour associations are automatic (Dixon et al., 2000; Mattingley et al.,
2001), but it does not necessarily show that it is sensory or perceptual (Ramachandran
& Hubbard, 2001a,b). We have noticed that it also often produces a strong visceral
discomfort like ‘nails scratching a blackboard’. Perhaps the ‘hyperconnectivity’
genes cause an excess of connections between sensory and limbic structures like
the amygdala, so that even a trifling discord produces a disproportionately large
abhorrence (see Cytowic, 1989/2002; Ramachandran & Hubbard, 2001a). We
are testing this theory by monitoring galvanic skin response (GSR), which
indexes emotional arousal.
(d) Does a given number evoke the same colour across different synaesthetes?
Synaesthetic colour associations remain stable in any given synaesthete, even
when tested over intervals of up to one year (Baron-Cohen et al., 1993). But does
the same grapheme tend to evoke the same colour across different synaesthetes?
The answer is no. One synaesthete might see A as red, another might see it as
green (Day, 2001). But the associations are not random either. There is a higher
chance that A will be red than that it will be (say) blue or yellow. Although such
trends have been noticed before no explanation was offered. We suggest that it
may reflect the manner in which phonemes (in higher synaesthetes — see below)
are mapped near the TPO junction in a systematic topographic manner, which in
turn would make certain types of cross-activation more likely than others (e.g.
front vowels might activate long wavelengths). Similarly, graphemes might be
mapped in ‘form space’ in the fusiform in such a way that certain colour corre-
spondences with colour neurons in V4 are more likely than others.
A systematic search for such correlations has yet to be attempted and the few
already undertaken have yielded ambiguous results (Day, 2001; Shanon, 1982).
An analogy with the periodic table of elements might be appropriate. Initial
attempts to classify elements produced a certain non-random clustering of prop-
erties (e.g. the alkaline metals vs the halogens) but no rhyme or reason could be
discerned until Mendeleev noticed that when arranged according to atomic
weights, the properties tended to repeat. When discrepancies emerged
Mendeleev actually insisted that the empirical data on atomic weights was
wrong, and later research has vindicated his view. Indeed he was even able to
predict the existence — and properties — of missing elements. We believe it is
only a matter of time before analogous correlations and patterns emerge for the
rules of cross-activation in synaesthesia. For instance, it may not initially be
obvious why the arbitrary vowel sequence AEIOU should map in a non-arbitrary
manner to a certain sequence of colours (and we have seen some hints of this
happening). But the point is that the sequence AEIOU may not be arbitrary (see
also Marks, 1975). It may reflect progressively anterior mouth and tongue articula-
tions which in turn might be mapped in a topographically organized phoneme
II: Synaesthesia Is a Sensory Phenomenon
Work in our laboratory has shown that synaesthesia is a genuine sensory phe-
nomenon (Ramachandran & Hubbard, 2001a,b). The subject is not just ‘imagin-
ing the colour’, nor is the effect simply a memory association (e.g. from having
played with coloured refrigerator magnets in childhood). For example, if several
2s are scattered among a matrix of randomly placed 5s, the global shape formed
by the embedded 2s is very hard to discern; normal subjects take several seconds
to find the shape because the 2s and 5s are composed of the same features three
horizontal lines and 2 vertical lines. But if a grapheme–colour synaesthete looks
at it he instantly — or very quickly — sees the global shape as a red triangle or
square against a background of green 2s (Ramachandran & Hubbard, 2001a).
This shows two things: First, that the phenomenon is genuine, for if it were not,
how could they be performing the task better than non-synaesthetes? Second, it
shows that synaesthesia is a sensory phenomenon; the induced colour can lead to
pop-out and segregation and only perceptual features processed early in visual
processing can lead to segregation (Beck, 1966; Treisman, 1982).
We proposed that number–colour synaesthesia is caused by cross-activation
between the ‘number grapheme area’ in the fusiform gyrus and the colour area
V4 that is also in the fusiform. The elegant fMR brain imaging work of Jeffrey
Gray and his colleagues (Nunn et al., 2002) and preliminary imaging results
from our group (Hubbard et al., 2003; in prep) are also consistent with this
‘cross-activation theory’. Although the vague notion that synaesthesia is the
result of ‘cross-wiring’ in the brain is probably as old as the phenomenon itself,
only in recent years has the idea been formulated in terms of precise anatomical
structures so that it can be tested experimentally.
One of the objections to cross-activation as the correct explanation is the fact
that synaesthesia is often directional. For instance numbers are seen coloured but
presenting colours doesn’t seem to evoke letters or numbers. This may have
something to do with the manner in which certain sensory dimensions like colour
are represented in brain maps, as opposed to the way in which numbers are
mapped. This difference might confer an inherent bias toward unidirectional
activation. For example, when a number evokes a colour then there is something
in the visual image — namely the number — to which the colour can be ascribed.
On the other hand, were a colour to evoke a number, where would the number be
seen and how big would it be? It would have to be ‘free floating’and that may not
be possible. We also think of metaphors as arbitrary but in fact they are not
(Lakoff & Johnson, 1980). We suggest that the nonarbitrariness both of
synaesthesia and of metaphor (and their directionality) arise because of con-
straints imposed by evolution and by neural hardware (Ramachandran &
Hubbard, 2001a). For example, you say ‘loud shirt’ but you rarely say ‘red
sound’; you say ‘sharp taste’ but rarely ‘bitter touch’.
In some bilingual synaesthetes (e.g., Chinese–English) one language alone
had coloured graphemes whereas the other did not. One bilingual synaesthete
even told us that graphemes in her first language were coloured but not second
language graphemes, suggesting selective cross-activation between colour and
one language alone. This is consistent with lesion data showing preservation of
one language with impairments in a second suggesting that the two languages
may be mapped in separate brain regions.
III: Synaesthesia and Metaphor
Although synaesthesia has been known for more than a century it was often
treated as bogus; the subjects were thought to be either faking it, on drugs, or just
plain crazy. Or it was suggested that they were just being ‘metaphorical’as when
you and I say ‘loud shirt’ or ‘warm hue’. Today, when the reality of synaesthesia
is accepted, we can explore positively the phenomenon’s physiological connec-
tion with sense-related metaphorical associations, and ask whether normal peo-
ple also experience synaesthesia. We all speak of certain smells — like nail
polish — being sweet, even though we have never tasted them. This might
involve close neural links and cross-activations between smell and taste, which
can be thought of as a form of synaesthesia that exists in all our brains. This
would not only make sense functionally — e.g. fruits are sweet and also smell
‘sweet’ like acetone — but also structurally: the brain pathways for smell and
taste are closely intermingled and project to the same parts of the frontal cortex.
Then consider the fact that even as infants we scrunch up our noses and raise
our hand when we encounter disgusting smells and tastes. Why is it that in all
cultures we use the same word and make the same facial expression for a person
who is morally disgusting? Why the same word as for taste? Why not say the
immoral person is ‘painful’? We suggest that once again this is because of evolu-
tionary and anatomical constraints. In lower vertebrates certain regions of the
frontal lobes have maps for smell and taste, but as mammals became more social
the same maps were usurped for social functions such as territorial marking,
aggression and sexuality, eventually culminating in mapping a whole new social
dimension: morality. Hence the interchangeable words and facial expressions for
both olfactory/gustatory disgust and moral disgust (Ramachandran and Hub-
bard, 2001a).
There may be neurological disorders that disturb metaphor and synaesthesia.
This has not been studied in detail but we have seen disturbances in the Bouba/
Kiki effect (Ramachandran & Hubbard, 2001a) as well as with proverbs in
patients with angular gyrus lesions. It would be interesting to see whether they
have deficits in other types of synaesthetic metaphor, e.g. ‘sharp cheese’or ‘loud
shirt’. There are also hints that patients with right hemisphere lesions show prob-
lems with metaphor. It is possible that their deficits are mainly with spatial meta-
phors, such as ‘He stepped down as director’.
Schizophrenics have problems with metaphors, often interpreting them literally.
(When asked what does ‘A stitch in time saves nine’ mean, they might say, ‘It’s
important to add several stitches before the hole becomes too large’.) They also
have difficulty with abstraction, yet ironically they are very good at making puns,
often doing so without intending to be funny. (E.g. when asked ‘What does a man
have in common with an elephant?’ instead of saying, ‘They are both alive’ or
‘they are both mammals’they say, ‘They can both carry a trunk’.) Both metaphors
and puns involve revealing hidden similarities, so why are schizophrenics bad at
one and good at the other? It may be because puns are in some ways the opposite of
metaphors; a metaphor reveals a deep similarity whereas a pun is a superficial sim-
ilarity masquerading a deep one, hence its comic appeal.
If we are to understand the neural basis of abstract thought and metaphor we
need to study the manner in which they break down — piecemeal — in neurol-
ogy and psychiatry; no progress can be made by lumping them all together
under ‘dementia’ which is the current practice. There is also scope for studying
the opposite trend, where enhanced mental performance is found, for instance in
memory. Luria (1968) described the case of S, a famous mnemonist, who seemed
to have unlimited memory due to his five-fold synaesthesia (that is, all five
senses were linked in him). Some of our ‘lower synaesthetes’ have told us they
learnt to type faster than their peers because all the keys on typewriter key pad
were colour coded, making them easier to remember (see also Smilek et al., 2002).
IV: Synaesthesia and the Riddle of Qualia
We offer an empirical solution to the question that has long puzzled philoso-
phers: How does the activity of neurons in the sensory (and other areas) in the
brain give rise to the subjective quality — the ‘qualia’ of sensations like red or
green or pain? The neurons in V4 (and other colour centres) are not that different
physically from (say) the neurons in auditory cortex concerned with hearing, so
why does their activity feel so utterly different?
One tool for probing this question is the ‘martian colour effect’, an unusual
tinting of colours evoked synaesthetically, which is most obvious and pro-
nounced in a colour-blind synaesthete we have tested (Ramachandran & Hub-
bard, 2001b), but occurs in ‘regular’ synaesthetes as well. We attribute this
colour distortion to the fact that the colours evoked by cross-activation in the
fusiform ‘bypass’ earlier stages of colour processing, and therefore may confer
an unusual (‘martian’) tint to the colours evoked. This is an important finding,
for it suggests that the qualia label — the subjective experience of the colour sen-
sation — depends not merely on the final stages of processing but on the total
pattern of neural activity, including the earlier stages.
Further support for the view that synaesthetic colours are evoked early in
visual processing and are genuinely sensory comes from four additional studies
we have done.
First, if the contrast of the number is lowered the colour becomes less vivid
and at low contrast (< approximately 10%) the colour vanishes even though the
number is clearly visible. In our first synaesthete, JC, the saturation of induced
colour decreased monotonically with contrast, and he reported that he did not
experience any colours below about 8% to 9% contrast even when the number
was still clearly visible (Hubbard & Ramachandran, 2002). Further, in 2002, we
also informally explored the question of whether it is the physical contrast or per-
ceived contrast that determines the saturation of the synaesthetic colour. In subject
JC, when we moved a page from a poorly illuminated room to bright sunlight, he
reported that the saturation seemed to change very little, if at all, despite several
orders of magnitude change in contrast. This implies that it is the perceived con-
trast that is important. Yet this cannot be the whole story. In our second test, we
showed JC a grey number that was printed on each of the two sides of a roof made
of a shaped, folded white card (the Mach card illusion). The card was illuminated
from one side, so the other side was in shadow. Even though the perceived con-
trast was the same on both sides, the colour saturation looked grossly different to
our subject. Conversely, if theMach card was mentally reversed in depth to change
perceived contrast, the vividness of colours remained constant. This implies some
degree of dependence on the physical rather than perceived contrast.
Second, the colour also vanished if two numbers (say 2 and 5) were alternated
in time at 4 to 5 Hz (Ramachandran & Hubbard, 2001b), even though the alterna-
tion of the numbers themselves was clearly visible at much higher rates (e.g., 15
Hz). Such a high-level of sensitivity to the elementary physical parameters defin-
ing the grapheme also supports our view that the effect is indeed sensory.
Third, we also wondered about spatial interactions; that is, what happens if
you have two graphemes close to each other, as in a double-digit number like 25?
The answer is she sees the corresponding two colours: there is no special colour
for the higher number and nor do the colours mix. But if the numbers were too
close spatially, the colours cancelled or neutralized each other , even though they
could be clearly resolved. Nevertheless, a number rendered unidentifiable by
two flanking numbers (a situation known as ‘crowding’) can still evoke
synaesthetic colours under certain conditions (Hubbard & Ramachandran, 2001;
Ramachandran & Hubbard, 2001a). Conversely if the two different letters or
numbers evoked the same colour then they enhanced each other.
Fourth, the synaesthetically induced colours can provide an input to apparent
motion, even though their inducing elements are uncorrelated across frames
(Ramachandran & Hubbard, 2002). We presented two alternating frames. In Frame
1, a matrix of randomly placed 2s and had a cluster of 5s embedded within it. In
Frame 2, an uncorrelated matrix of 2s was presented, and the cluster of 5s was dis-
placed by 4 degrees. Controls saw random incoherent motion, while JC reported
seeing apparent motion of the 5s based on the synesthetically induced colours.
These remarks appear to hold only for a subset of synaesthetes whom we call
‘lower synaesthetes’. We later came across synaesthetes in whom even days of
the week and months of the year evoked colours. In some of these it’s the first let-
ter of the day (e.g. T for Tuesday) that determines the colour of the day but in oth-
ers we suggest it’s the concept of ordinality or position in a numerical sequence
that determines the induced colour. It is not known where such sequences are
represented but the angular gyrus (especially the left one) is a good candidate
since damage to it results in dyscalculia. We suggested, therefore, that there may
be a subset of synaesthetes — whom we call ‘higher synaesthetes’ — in whom
the cross activation occurs between ‘higher colour areas’ near the TPO junction
and representation of ordinality in the angular gyrus. These are to be contrasted
with lower synaesthetes in whom the cross activation is in the fusiform and
evoked by visual form of the grapheme alone. At present the terminology is no
more than a temporary shorthand, and it remains to be seen if there is a clear dis-
tinction between ‘higher’ and ‘lower’ synaesthetes. The distribution might be
bimodal or they may just represent different points on a continuum. What is clear
is that even among number–colour synaesthetes there are at least two types,
probably more depending on what genes are expressed at what stage anatomi-
cally in the number/colour processing hierarchy.
The visual representation of graphemes in the fusiform must be relayed to
higher phoneme areas in order to evoke the corresponding sounds. So another
form of higher synaesthesia would involve the evoking of colours not by numeri-
cal sequence but by the phoneme corresponding to the grapheme. In such indi-
viduals the entire word often gets tinged with the colour of its first letter. Such
observations imply that synaesthesia could also be used as a probe for understand-
ing the manner in which visual graphemes interact with auditory phonemes in the
representation of syllables and words in the brain, a topic that has traditionally
been studied only by linguists. Again, there may be differences between higher
and lower synaesthetes, with only the latter showing these effects.
We presented the sentence ‘Finished files are the result of years of scientific
study combined with the experience of years’ to one of our higher synaesthetes
and asked her to count the number of ‘f’s in it. Normal, non-synaesthetes usually
detect only three: they are ‘blind’ to the ‘f’s in the three ‘of’s because it is a high
frequency word, and is not processed as a string of letters. Likewise our
synaesthete said that she initially saw only three ‘red graphemes’ in the sentence,
but on careful scrutiny saw all six ‘f’s tinged red. Again this observation suggests
that the overall phonetic context within which the letter is embedded can influ-
ence the nature and extent of cross-activation. We usually think of vision as a
one-way hierarchy or bucket brigade, but such contextual effects must be based
on ‘top down’ influences from the hearing centres feeding back into the visual
grapheme center in the fusiform.
The reverse side of the coin from being ‘blind’ to a character is to imagine a
number or letter that is not physically presented. Many synaesthetes reported
that when they visualised a number in front of them it was, surprisingly, more
strongly coloured than when they looked at a real number. We suggest this is
because when you imagine something visually there is activation of the same
brain areas — such as the grapheme area in the fusiform — that are driven by
actual physical colours, but without the real black (or white) number coming in
from the retina and competing with the colour experience, this imagined number
actually evokes a stronger experience of the corresponding colour. It should
eventually be possible to test such conjectures using brain imaging.
One prediction we made (Ramachandran & Hubbard, 2001a) from this
scheme is that the psychophysical properties of the colour evoked (e.g. ‘segrega-
tion and pop out’ sensitivity to contrast and flicker, etc) should be different for
lower and higher synaesthetes, a prediction that has now been borne out (Hub-
bard & Ramachandran, 2002; Hubbard et al., 2003). Several additional tests
remain to be done to see how clear the distinction is. For instance, we have pre-
liminary evidence from our Mach card experiment that it is the physical rather
than phenomenal (i.e. post lightness constancy) contrast that drives the
synaesthetic colour, but would this also hold for higher synaesthetes?
V: Synaesthesia Come of Age
For any new phenomenon — a Kuhnian ‘anomaly’ to grab people’s attention —
three different criteria must be fulfilled. First, the phenomenon must be real and
reliably repeatable. Second, there must be a candidate mechanism to explain the
effect in terms of known laws. And third, it must have broad implications beyond a
narrow confines of one speciality. Thus, telepathy fulfills criterion three (vast
implications if true) but not one or two, so it does not get taken seriously. Bacterial
transformation — the transmutation of one species of bacterium A into another
species B — by merely culturing the chemical extract of B with A satisfied crite-
rion one (it was reliably repeated and published in a famous journal) and criterion
three (it challenged the basic law of biology that species are immutable and stable)
yet it was ignored because it was discovered in the pre DNA era so no one could
even conceive of a mechanism that could explain it. Similarly, continental drift
satisfied criterion one — many observations pointed to it (like the distribution of
fossils, the ‘fit’ between continent outlines, etc.) and criterion three — it was
obviously important — but it was rejected because, again, there was no mecha-
nism that could account for it, that is until plate tectonics was discovered.
The problem with synaesthesia was that until recently none of these three cri-
teria were fulfilled. Consequently synaesthesia has long been ignored by ‘main-
stream’ neuroscience and psychology. Without unambiguous tests like our ‘pop
out’ test — segregation of 2s from 5s — it was hard to be sure that they really
were actually seeing the colour, so it was not clear if the phenomenon was real.
Second, no candidate mechanism was proposed except in very vague terms (such
as ‘mixing up senses’ in some primitive brain region, an idea that was too vague
to be testable). The idea we proposed — that in number colour synaesthesia there
is cross-activation specifically in the fusiform gyrus (in lower synaesthetes) and
TPO junction/angular gyrus (in higher synaesthetes) has the advantage that it can
be tested with brain imaging (see, e.g., Hubbard et al., 2003; Nunn et al., 2002).
And third, we have tried to show that synaesthesia is no mere quirk in some peo-
ple’s brains; it has broad implications and may give us an experimental handle on
elusive phenomena like metaphor, abstract thinking and the evolution of language.
It would be wrong, of course, to suggest that synaesthesia is now fully under-
stood. One very common type of synaesthesia, originally noted by Francis
Galton but still very little studied, involves what is called the ‘number line’,
which runs in families. If asked to visualize numbers the subject finds that they
are arranged in a continuous line extending from one point in the visual field to
another remote point — say from the top left corner to bottom right. The line
does not have to be straight — it is sometimes curved or convoluted or even dou-
bles back on itself. In one of our subjects the number line is centred around
‘world centred’ coordinates — he can wander around the 3-D landscape of num-
bers and ‘inspect’ the numbers from novel noncanonical vantage points. Usually
the earlier numbers are more crowded together on the line and often they are also
coloured. Such individuals also often have ‘calendar lines’ depicting months of
the year or days of the week sequentially, phenomena that we plan to investigate
using brain imaging studies and by temporary ‘lesions’ in the brains of volun-
teers produced by magnetic stimulation.
Baron-Cohen, S., Harrison, J., Goldstein, L.H., Wyke, M. (1993), ‘Coloured speech perception: Is
synaesthesia what happens when modularity breaks down?’, Perception,22 (4), pp. 419–26.
Beck, J. (1966), ‘Effect of orientation and of shape similarity on perceptual grouping’, Perception and
Psychophysics,1, pp. 300–2.
Cytowic, R.E. (1989/2002), Synesthesia: A Union of the Senses (2nd ed. New York: Springer-Verlag).
Day, Sean A. (2001), ‘Trends in synaesthetically coloured graphemes and phonemes’,
Dixon, M.J., Smilek, D., Cudahy, C. & Merikle, P.M. (2000), ‘Five plus two equals yellow’, Nature,406
(6794), p. 365.
Galton, F. (1880), ‘Visualised numerals’, Nature,22, pp. 494–5.
Hubbard, E.M. & Ramachandran, V.S. (2001), ‘Synesthesia, blindsight, crowding and qualia’, Society
for Neuroscience Abstracts,27, 681.11.
Hubbard, E.M. & Ramachandran, V.S. (2002), ‘Different types of synesthesia may depend on different
brain loci’, Society for Neuroscience Abstracts,28, 220.2.
Hubbard, E.M., Ramachandran, V.S. & Boynton, G.M. (2003), ‘Cortical cross-activation as the locus of
grapheme-color synesthesia’, 3rd Annual Meeting of the Vision Sciences Society, Sarasota, FL.
Hubbard, E. M., Ramachandran, V.S. & Boynton, G.M. (in prep), ‘Synesthetic colors activate color
selective visual areas (V4/V8/hV4)’, ms in preparation.
Lakoff, G. and Johnson, M.H. (1980), Metaphors We Live By (Chicago: University of Chicago Press).
Luria, A.R. (1968), The Mind of a Mnemonist (New York: Basic Books).
Marks, L. E. (1975). ‘On colored–hearing synesthesia: Cross-modal translations of sensory dimensions’,
Psychological Bulletin,82, pp. 303–31.
Mattingley, J.B., Rich, A.N., Yelland, G. and Bradshaw, J.L. (2001), ‘Unconscious priming eliminates
automatic binding of colour and alphanumeric form in synaesthesia’, Nature,410, pp. 580–2.
Nunn, J.A., Gregory, L.J., Brammer, M., Williams, S.C.R., Parslow, D.M., Morgan, M.J., Morris, R.G.,
Bullmore, E.T., Baron-Cohen, S., Gray, J.A. (2002), ‘Functional magnetic resonance imaging of
synaesthesia: Activation of V4/V8 by spoken words’, Nature Neuroscience.5(4), pp. 371–5.
Ramachandran, V.S. and Hirstein, W. (1999), ‘The science of art: A neurological theory of aesthetic
experience’, Journal of Consciousness Studies,6(6–7), pp. 15–51.
Ramachandran, V.S. and Hubbard, E.M. (2001a), ‘Synaesthesia: A window into perception, thought and
language’, Journal of Consciousness Studies,8(12), pp. 3–34.
Ramachandran, V.S. and Hubbard, E.M. (2001b), ‘Psychophysical investigations into the neural basis of
synaesthesia’, Proceedings of the Royal Society of London, B,268, pp. 979–83.
Ramachandran, V.S. and Hubbard, E.M. (2002). ‘Synesthetic colors support symmetry perception,
apparent motion and ambiguous crowding’, Abstracts of the Psychonomic Society,7,p.79.
Shanon, B. (1982), ‘Colour associates to semantic linear orders’, Psychological Research,44, pp. 75–83.
Smilek, D., Dixon, M. J., Cudahy, C., & Merikle, P. M. (2002), ‘Synesthetic color experiences influence
memory.’, Psychological Science,13, pp.548–52.
Treisman, A. (1982), ‘Perceptual grouping and attention in visual search for features and for objects’,
Journal of Experimental Psychology: Human Perception and Performance,8(2), pp. 194–214.
Paper received April 2003
... Other, structural neuroimaging studies, have found evidence of differences in the connections between brain regions in people with synesthesia, suggesting a hard-wired organizational predisposition is necessary for the condition to emerge [12]. Interestingly, Ramachandran and Hubbard [13][14][15] have proven without doubt that synesthesia is indeed a perceptual effect and not a cognitive or memory driven experience, as was once thought. ...
... Interestingly, Ramachandran and Hubbard have also shown that "associations DOI: /10.5772/intechopen.110777 between shapes and sounds are absent in individuals with damage to the angular gyros, suggesting that this is a robust neuropsychological phenomenon" [13][14][15]. ...
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‘Visual Music’ has a long history, much longer than most people realize. Over time, several eminent scientists, musicians, and artists have tried to establish correspondences between sound and vision. Some of these efforts were based on scientific principles, some on genuine synesthetic experiences, while others were more obviously creative aesthetic choices. With the resurgence of interest in this field, the argument presented here is that now is the time to re-evaluate this canon of knowledge, to identify more clearly, and expand the core concepts at its center. A selection of works, by pioneering film makers from the twentieth century, are examined from a semiotically informed perspective, to reevaluate some of the history of Visual Music alongside new ideas from the adjacent fields of science, psychology, and neuroscience. To this end a range of principles/parameters are outlined that arguably constitute the fundamentals of all creative approaches that translate between sound and vision going forward.
... Elle donne un aperçu des codes primaires que le cerveau utilise pour se représenter des concepts ou des stimuli sensoriels (les chiffres, le temps, la musique, les gens, etc.), illustre la diversité dans laquelle un stimulus peut être perçu et conçu et peut nous informer sur la relation entre une activité cérébrale et l'expérience subjective qui en découle (Ramachandran et Hubbard, 2003b). Les expériences synesthésiques sont des instruments permettant d'investiguer à la fois des mécanismes perceptuels et des expériences émotionnelles. ...
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La synesthésie est une condition neurologique dans laquelle une stimulation sensorielle ou cognitive dans une modalité spécifique engendre de façon automatique et involontaire une autre expérience perceptuelle inhabituelle. La synesthésie influencerait le développement de certaines habiletés cognitives, notamment sur le plan mnésique. Par ailleurs, une hypothèse intuitive populaire au sein de la communauté scientifique stipule que ces expériences sensorielles atypiques facilitent la créativité. En effet, comme elles dotent d’un répertoire perceptuel original, il est concevable qu’elles puissent mener à une aptitude à faire des associations non conventionnelles entre diverses catégories d’éléments. Par conséquent, cette recherche qualitative vise à mieux comprendre les influences des expériences synesthésiques sur la créativité, du point de vue de ceux qui vivent ces expériences. Dans le but de mieux comprendre la phénoménologie de la synesthésie en créativité, les questions de notre recherche se résument ainsi : Quel sens peut avoir l’expérience de la synesthésie en créativité et quelles répercussions a-t-elle sur la créativité? Nous sommes intéressés à comprendre comment la synesthésie peut être perçue, avoir de l’influence et être utilisée lors d’un processus créatif. À notre connaissance, il s’agit de la première étude à explorer la phénoménologie de la synesthésie tant auprès de plusieurs individus qu’au sein de plusieurs formes de synesthésie, à l’égard d’une caractéristique soi-disant centrale à cette condition, soit la créativité. Dans le cadre de cette recherche, 17 personnes avec diverses synesthésies, âgées de 21 ans à 72 ans, ont été rencontrées afin de partager leurs expériences lors d’entretiens individuels semi-dirigés. Ces entrevues ont été retranscrites et analysées d’après la méthode phénoménologique de recherche en psychologie. Au final, la structure fondamentale du phénomène étudié qui émerge de nos analyses comprend les 10 thèmes suivant en ce qui a trait au sens donné à l’expérience de la synesthésie sur le plan de la créativité : 1) L’expérience de la synesthésie oriente, module le processus créatif en fonction des associations synesthésiques afin d’être dans un état particulier et d’accroître le bien-être; 2) L’expérience de la synesthésie constitue un apport sensoriel, perceptuel et émotionnel à la créativité; 3) L’expérience de la synesthésie optimise les fonctions cognitives; 4) L’expérience de la synesthésie alimente la stimulation intellectuelle et la motivation dans un processus créatif; xvi 5) L’expérience de la synesthésie donne un sens à des éléments et à un vécu; 6) L’expérience de la synesthésie est perçue comme un système instinctif qui influence la créativité, une intuition à l’origine d’un processus de décision ou un réflexe consistant à transposer des associations qui sont indépendantes de la cognition; 7) L’expérience de la synesthésie permet de mieux se connaître, de s’identifier, d’exprimer et d’assumer ce qui constitue son individualité; 8) L’expérience de la synesthésie constitue une courroie de communication avec autrui, d’échange avec d’autres réalités; 9) L’expérience de la synesthésie peut ne pas avoir d’influence sur la créativité; les associations synesthésiques peuvent être perçues comme des états de faits qui sont d’utilité pratique et qui n’ont pas de répercussion sur les choix face à des besoins; 10) L’expérience de la synesthésie peut être un frein à la créativité. La présente étude a permis de développer une meilleure compréhension des composantes de la créativité, de faire avancer l’état des connaissances sur les expériences synesthésiques et d’identifier le coeur de leurs influences sur la créativité. Pour la première fois, l’étendue des avantages et des inconvénients des expériences synesthésiques sur la créativité a été exposée. Mener cette étude auprès de synesthètes qui présentent une variété de synesthésies a aussi permis d’identifier des processus sous-jacents à la créativité qui sont communs dans le vaste spectre de la synesthésie et d’amener des pistes d’explications quant aux différences individuelles pouvant émerger. Du coup, divers processus qui peuvent influencer et alimenter la créativité chez tous les individus ont été mis en lumière. Enfin, cette recherche peut apporter un éclairage sur les mécanismes universels d’interactions entre les sens et sur leur usage à certaines fins. De futures études avec de larges échantillons de participants devraient tenter de départager différents attributs de la synesthésie et d’explorer leur contribution respective dans divers aspects de la cognition et des émotions. Les répercussions de l’exploitation d’associations automatiques, synesthésiques ou non, pourraient aussi faire l’objet d’études dans les cadres d’interventions thérapeutiques et pédagogiques. Enfin, la mise sur pied de regroupements de chercheurs en synesthésie et de synesthètes pourrait stimuler le développement et la diffusion des connaissances sur la synesthésie et sur le potentiel humain, démarginaliser cette condition et déconstruire des conceptions erronées, et faire accroître l’épanouissement des individus de la grande communauté synesthète.
... 5 While both of these types of synesthesia describe inducer-concurrent pairs, the distinction is used to highlight the way the concurrent is experienced. For projector synesthetes, concurrents are experienced as projected outward, which has led some researchers to claim that the former is a perceptual (as opposed to a merely cognitive) phenomenon (Ramachandran & Hubbard, 2003; although see Brogaard, 2014). For associator synesthetes, concurrents are experienced internally (in the "mind's eye" as it were) in the way imaginative episodes are experienced (Brogaard, 2014). ...
Objectophilia (also known as objectum-sexuality) involves romantic and sexual attraction to specific objects. Objectophiles often develop deep and enduring emotional, romantic, and sexual relations with specific inanimate (concrete or abstract) objects such as trains, bridges, cars, or words. The determinants of objectophilia are poorly understood. The aim of this paper is to examine the determining factors of objectophilia. We examine four hypotheses about the determinants of objectophilia (pertaining to fetishism, synesthesia, cross-modal mental imagery, and autism) and argue that the most likely determining factors of objectophilia are the social and non-social features of autism. Future studies on the determinants of objectophilia could enhance our understanding and potentially lessen the marginalization experienced by objectophiles.
... 5 While both of these types of synesthesia describe inducer-concurrent pairs, the distinction is used to highlight the way the concurrent is experienced. For projector synesthetes, concurrents are experienced as projected outward, which has led some researchers to claim that the former is a perceptual (as opposed to a merely cognitive) phenomenon (Ramachandran & Hubbard, 2003; although see Brogaard, 2014). For associator synesthetes, concurrents are experienced internally (in the "mind's eye" as it were) in the way imaginative episodes are experienced (Brogaard, 2014). ...
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Objectophilia (also known as objectum-sexuality) involves romantic and sexual attraction to specific objects. Objectophiles often develop deep and enduring emotional, romantic, and sexual relations with specific inanimate (concrete or abstract) objects such as trains, bridges, cars, or words. The determinants of objectophilia are poorly understood. The aim of this paper is to examine the determining factors of objectophilia. We examine four hypotheses about the determinants of objectophilia (pertaining to fetishism, synesthesia, cross-modal mental imagery, and autism) and argue that the most likely determining factors of objectophilia are the social and non-social features of autism. Future studies on the determinants of objectophilia could enhance our understanding and potentially lessen the marginalization experienced by objectophiles.
... Synesthetes may see sounds, smell words, touch tastes, or taste letters, for example (van Leeuwen et al., 2016). When grapheme-color synesthetes see a number or a letter, they see a color at the same time (Figure 4), which is different from just imagining the color or making an association based upon memory (Ramachandran and Hubbard, 2003). ...
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Human perception has long been a critical subject of design thinking. While various studies have stressed the link between thinking and acting, particularly in spatial experience, the term “design thinking” seems to disconnect conceptual thinking from physical expression or process. Spatial perception is multimodal and fundamentally bound to the body that is not a mere receptor of sensory stimuli but an active agent engaged with the perceivable environment. The body apprehends the experience in which one’s kinesthetic engagement and knowledge play an essential role. Although design disciplines have integrated the abstract, metaphoric, and visual aspects of the body and its movement into conceptual thinking, studies have pointed out that design disciplines have emphasized visuality above the other sensory domains and heavily engaged with the perception of visual configurations, relying on the Gestalt principles. Gestalt psychology must be valued for its attention to a whole. However, the theories of design elements and principles over-empathizing such visuality posit the aesthetics of design mainly as visual value and understate other sensorial and perceptual aspects. Although the visual approach may provide a practical means to represent and communicate ideas, a design process heavily driven by visuality can exhibit weaknesses undermining certain aspects of spatial experience despite the complexity. Grounded in Merleau-Ponty’s notion of multisensory perception, this article discusses the relationship between body awareness and spatial perception and its implication for design disciplines concerning built environments. Special attention is given to the concepts of kinesthetic and synesthetic phenomena known as multisensory and cross-sensory, respectively. This discussion integrates the corporeal and spatiotemporal realms of human experience into the discourse of kinesthetic and synesthetic perceptions. Based on the conceptual, theoretical, and precedent analyses, this article proposes three models for design thinking: Synesthetic Translation, Kinesthetic Resonance, and Kinesthetic Engagement. To discuss the concepts rooted in action-based perception and embodied cognition, this study borrows the neurological interpretation of haptic perception, interoception, and proprioception of space. This article suggests how consideration of the kinesthetic or synesthetic body can deepen and challenge the existing models of the perceptual aspects of environmental psychology adopted in design disciplines.
In Nyāya philosophy, a special kind of extraordinary sensory connection is admitted named jñānalakṣaṇā pratyāsatti or jñānalakṣaṇa sannikarṣa. It is held that sometimes our sense-organ can be connected to such an object which is not amenable to the operating sense-organ. In such cases, cognition (jñāna) plays the role of sensory connection and connects the content of itself to the operating sense-organ. The paradigmatic example of jñānalakṣaṇa perception is to ‘see’ fragrant sandal through visual sense from non-smellable distance. This hypothesis of jñānalakṣaṇa has been criticized by the opponents being considered as counterintuitive, mysterious and theoretically overloaded. This paper tries to demystify the notion. It shows that although it seems to be metaphysically mysterious phenomenon at first sight, it is not so at all. The paper explores the psychological process involved in this sensory connection. The hypothesis is shown to have sufficient explanatory power, because the Naiyāyikas have used this hypothesis to explain five different epistemic situations. Hence, this paper argues that it is not a theoretical overload. The opponents counter-argue that all those five cognitive situations can be explained without admitting jñānalakṣaṇa. Moreover, if we admit jñānalakṣaṇa, then a particular kind of inference will become redundant. The paper answers all those objections and defends the hypothesis. The second part of the paper presents an empirical evidence in support of the hypothesis. The arguments leveled against the hypothesis of jñānalakṣaṇa can be contested on the ground that they try to disprove something which is supported on experimental ground. Experiments represent universally acceptable objective facts supported by experience—denying which amounts to anubhavavirodha, which philosophers would want to avoid. Hence, supporting jñānalakṣaṇa on the ground of scientific experiments can be considered as a philosophical stand. Now, there is a clinically recognized and neurophysiologically proved condition, called synaesthesia, where stimulation of a particular sensory modality automatically and involuntarily activates a different sensory modality simultaneously without a direct stimulation of the second modality. As for example, when a sound → colour synaesthete listens to a particular tone such as C-sharp, she visualizes particular colour, such as blue, in her mind’s eye; for a grapheme → colour synaesthete a particular number or alphabet is always tinged with a particular colour. This paper shows that the cognitive process involved in synaesthesia lends support to the hypothesis of jñānalakṣaṇa pratyāsatti. It has been proved through several experiments that it is a genuine perceptual phenomenon and is not a confabulation of memory. There are several alternative theories which explain the phenomenon neurophysiologically. The paper discusses the most popular one: the cross-activation hypothesis. There are two major objections against the project of comparing jñānalakṣaṇa with synaesthesia. First, synaesthesia is a neurological condition present in a few numbers of people whereas jñānalakṣaṇa is claimed to be universal phenomenon. Second, syneasthesia is a sensory experience whereas jñānalakṣaṇa involves application of concepts. The paper answers these questions. Firstly, multimodal processing in the brain is a universal phenomenon; secondly, there is a form of synaesthesia where top-down processing is involved. In those cases, concepts play important role for having synaesthetic experience.
Sensory experiences build our worlds, yet in illustration as a practice and subject we often focus so much on the visual stimuli and materiality around us to inform our image-making. Why have we not focused on mediating our range of senses to form a supercharged version of our image-making tools? We live in a time and world that can often be an assault on the senses. But how are these informed and what purpose do they serve in education to help communicate ideas in illustration practices? How can senses be subverted to rejuvenate creative processes? How do senses inform our identity, our memories, nostalgia and in turn, our creative practices? This article is an attempt to explore these questions through examples in Jhinuk Sarkar’s research and practice as an educator and illustrator.
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Este artigo se trata de uma reflexão interdisciplinar sobre a escuta. A motivação para tal veio de um incômodo crescente com a objetividade presumida com que a escuta costuma ser tratada no âmbito da teoria e análise musical, especialmente no contexto da música eletroacústica, onde a escuta rapidamente se tornou tema de pesquisa. Simultaneamente reconheço que defender o extremo oposto, uma total subjetividade da escuta, não só inviabiliza o estudo da música como experiência compartilhada, como de fato não faz jus à experiência que conheço como música. Partindo deste problema discuto uma série de autores que trataram da escuta ou da percepção, em especial a fenomenologia de Merleau-Ponty, no intuito de construir uma base teórica que permita recolocar a questão da escuta no estudo musical – em especial sobre a delimitação do(s) objeto(s) da escuta: o som, ou a música.
A Flash of Light is an intriguing book that starts at the beginning of time itself and then winds its way through a host of fascinating light related topics including the hues of aliens sunsets, the psychology of colour, and the chemistry of LCD screens. Written as part of a novel experiment, editors Mark Lorch and Andy Miah hatched a plan to collect a critical mass of academics in a room and charged them with writing a popular science book, under the watchful eye of the general public at the Manchester Science Festival. The result is an enlightening look into the science behind colour and light, encompassing biology, chemistry and physics and including simple and fun “try this at home” ideas to illustrate the concepts covered. Drawing on the experience of some of the UK’s best science communicators, this book will appeal to anyone with an interest in science. Its pacey, witty and engaging tone provides illuminating insight into how and why we see the universe the way we do.
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We investigated grapheme--colour synaesthesia and found that: (1) The induced colours led to perceptual grouping and pop-out, (2) a grapheme rendered invisible through `crowding' or lateral masking induced synaesthetic colours --- a form of blindsight --- and (3) peripherally presented graphemes did not induce colours even when they were clearly visible. Taken collectively, these and other experiments prove conclusively that synaesthesia is a genuine perceptual phenomenon, not an effect based on memory associations from childhood or on vague metaphorical speech. We identify different subtypes of number--colour synaesthesia and propose that they are caused by hyperconnectivity between colour and number areas at different stages in processing; lower synaesthetes may have cross-wiring (or cross-activation) within the fusiform gyrus, whereas higher synaesthetes may have cross-activation in the angular gyrus. This hyperconnectivity might be caused by a genetic mutation that causes defective pruning of connections between brain maps. The mutation may further be expressed selectively (due to transcription factors) in the fusiform or angular gyri, and this may explain the existence of different forms of synaesthesia. If expressed very diffusely, there may be extensive cross-wiring between brain regions that represent abstract concepts, which would explain the link between creativity, metaphor and synaesthesia (and the higher incidence of synaesthesia among artists and poets). Also, hyperconnectivity between the sensory cortex and amygdala would explain the heightened aversion synaesthetes experience when seeing numbers printed in the `wrong' colour. Lastly, kindling (induced hyperconnectivity in the temporal lobes of temporal lobe epilepsy [TLE] patients) may explain the purp...
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We present a theory of human artistic experience and the neural mechanisms that mediate it. Any theory of art (or, indeed, any aspect of human nature) has to ideally have three components. (a) The logic of art: whether there are universal rules or principles; (b) The evolutionary rationale: why did these rules evolve and why do they have the form that they do; (c) What is the brain circuitry involved? Our paper begins with a quest for artistic universals and proposes a list of ‘Eight laws of artistic experience’ -- a set of heuristics that artists either consciously or unconsciously deploy to optimally titillate the visual areas of the brain. One of these principles is a psychological phenomenon called the peak shift effect: If a rat is rewarded for discriminating a rectangle from a square, it will respond even more vigorously to a rectangle that is longer and skinnier that the prototype. We suggest that this principle explains not only caricatures, but many other aspects of art. Example: An evocative sketch of a female nude may be one which selectively accentuates those feminine form-attributes that allow one to discriminate it from a male figure; a Boucher, a Van Gogh, or a Monet may be a caricature in ‘colour space’ rather than form space. Even abstract art may employ ‘supernormal’ stimuli to excite form areas in the brain more strongly than natural stimuli. Second, we suggest that grouping is a very basic principle. The different extrastriate visual areas may have evolved specifically to extract correlations in different domains (e.g. form, depth, colour), and discovering and linking multiple features (‘grouping’) into unitary clusters -- objects -- is facilitated and reinforced by direct connections from these areas to limbic structures. In general, when object-like entities are partially discerned at any stage in the visual hierarchy, messages are sent back to earlier stages to alert them to certain locations or features in order to look for additional evidence for the object (and these processes may be facilitated by direct limbic activation). Finally, given constraints on allocation of attentional resources, art is most appealing if it produces heightened activity in a single dimension (e.g. through the peak shift principle or through grouping) rather than redundant activation of multiple modules. This idea may help explain the effectiveness of outline drawings and sketches, the savant syndrome in autists, and the sudden emergence of artistic talent in fronto-temporal dementia. In addition to these three basic principles we propose five others, constituting a total of ‘eight laws of aesthetic experience’(analogous to the Buddha's eightfold path to wisdom).
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Reviews colored-hearing synesthesia, in which sounds induce visual images (photisms). Colored hearing manifests correlations between dimensions of auditory and visual experience. Two general findings are that (a) the brightness of photisms varies with the brightness (density) of the inducing sounds and (b) the size of photisms varies with the size (volume) of the inducing sounds. In colored hearing produced by speech sounds, the induced hues and brightnesses can be related to the formant structures of the vowels. Synesthetes align dimensions on different modalities in ways that are qualitatively similar to the ways that nonsynesthetes align them (e.g., in phonetic symbolism). Synesthesia appears to be a cross-modal manifestation of connotative meaning in a pure sensory form; its inflexibility (compared to language) makes synesthesia less significant in adulthood than in childhood. (31/2 p ref)
A method in which as were asked to partition a pattern into two regions was used to investigate the perceptual grouping produced by changes in the orientation and shape of two-line figures. The results show that the judged similarity of the figures fails to predict the degree to which the figures form distinct perceptual groups. Grouping was most strongly influenced by differences in the orientation of the lines composing the figures. Crossing of lines making up the figures also affected grouping, but was less decisive than line orientation.
This article explores the effects of perceptual grouping on search for targets defined by separate features or by conjunction of features. Treisman and Gelade proposed a feature-integration theory of attention, which claims that in the absence of prior knowledge, the separable features of objects are correctly combined only when focused attention is directed to each item in turn. If items are preattentively grouped, however, attention may be directed to groups rather than to single items whenever no recombination of features within a group could generate an illusory target. This prediction is confirmed: In search for conjunctions, subjects appear to scan serially between groups rather than items. The scanning rate shows little effect of the spatial density of distractors, suggesting that it reflects serial fixations of attention rather than eye movements. Search for features, on the other hand, appears to independent of perceptual grouping, suggesting that features are detected preattentively. A conjunction target can be camouflaged at the preattentive level by placing it at the boundary between two adjacent groups, each of which shares one of its features. This suggests that preattentive grouping creates separate feature maps within each separable dimension rather than one global configuration.
People were asked whether they had strong colour associates (rather than associations) for different linear orders. Eighteen informants responded that they associated colours with numbers, and ten that they associated colours with the days of the week. The colours associated with both linear orders were consistent between subjects and correlated with each other. The order of the associates correlated with the order noted in the anthropological linguistic typology of Berlin and Kay (1969). Together, the patterns noted indicate that the association of colours with linear orders is an orderly cognitive phenomenon. While no causal explanation of the phenomenon is given, some implications are suggested.