Category: synaesthesia

When orgasm triggers a light show – The first ever study of synaesthetic sex

For people with synaesthesia, stimulation of one sense – or in some cases just thinking of a particular concept – triggers another kind of sensory experience. The most common form of the condition is for letters to trigger colour perceptions, but there are some truly strange variants, such as people for whom various swimming strokes trigger colours, and others who experience emotional sensations at the touch of different fabrics.

Although there are first-hand accounts in sex research that sound a lot like synaesthesia (e.g. a woman interviewed for a 1970 paper said that orgasm was accompanied by “fuzzy blackness with red and white muted bursts”), before now psychology has failed to investigate the possibility that, for some people, sexual feelings might be the trigger for synaesthetic sensations, and to ask what the implications are for their sex lives.

For a new study, a team led by Janina Nielsen surveyed 19 synaesthetes (2 men) who claimed to have sexual forms of the condition. Their answers were compared to 36 age-matched controls. The researchers also interviewed seven of the sexual synaesthetes. The average age of the participants was mid to late thirties.

The sexual synaesthetes described different perceptual sensations for different stages of sexual activity from arousal to climax. Initial fantasy and desire triggered the colour orange for one woman. As excitement built for another participant, this went together with colours of increasing intensity. With excitement plateauing, one person described fog transformed into a wall. Orgasm was then described as the wall bursting, “ringlike structures … in bluish-violet tones.” The final so-called resolution phase was accompanied for another participant with pink and yellow.

There’s no objective way of verifying the truth of these descriptions – perhaps the synaesthetic participants were being poetic rather than literal. However, many of them experience more common forms of synaesthesia (e.g. letters to colours), which showed consistency over time when tested – usually taken as mark of authenticity.

The survey results showed that the sexual synaesthetes scored higher than control participants for sexual desire and for altered states of consciousness during sex, including “oceanic boundlessness” (feelings of derealisation and ecstasy) and “visionary restructuaralisation” (hallucinations). Surprisingly perhaps, the synaesthetes also reported less sexual satisfaction than the controls. Their interview answers suggested this is because their synaesthetic experiences enrich their own sexual sensations but leave them feeling disconnected from their partner. It’s all very well if sex triggers your own personal light show, but if you can’t share it, well … it must be kind of isolating.

Nielsen and her team said these results should be treated with caution. This is “a pilot project” they said, “providing clues for further investigation.”


Nielsen J, Kruger TH, Hartmann U, Passie T, Fehr T, and Zedler M (2013). Synaesthesia and sexuality: the influence of synaesthetic perceptions on sexual experience. Frontiers in psychology, 4 PMID: 24137152

Further reading
From The Psychologist magazine: Barry R. Komisaruk, Carlos Beyer and Beverly Whipple view the subject of orgasms as an experience that is an integration of body, nervous system and the mind.

More on synaesthesia from the Digest archive.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

What colour is your breast-stroke? Or why synaesthesia is more about ideas than crossed-senses

People with synaesthesia experience odd sensations that make it seem as though their neural wires are crossed. A certain word might always come served with the same particular taste, or a letter or numeral might reliably evoke the same particular colour. But an emerging view among experts is that synaesthesia is grounded in concepts, not crossed senses. By this account, it’s certain ideas, regardless of which sense perceives them, that trigger a particular concurrent experience. The latest evidence for this comes from Danko Nikolic and his colleagues at the Max-Planck Institute for Brain Research. They’ve documented two synaesthetes, HT and UJ, who experience different swimming strokes, whether performing them, watching them or merely thinking about them, as always being a certain colour.

HT and UJ, both now aged 24, began swimming competitively at an early age and the sport continues to be an important part of their lives. The first test that Nikolic’s team performed was to present the pair with four black and white close-up photos of different swimming strokes and have them say which colour the strokes triggered using a book of 5500 colour shades. This was repeated four weeks later for HT and three weeks later for UJ. Three non-synaesthete control participants, all swimmers, were recruited for comparison. They similarly reported which colours the photos made them think of and they repeated the exercise after just a two-week gap.

The clear finding was that the difference from the first test to the second test in the precise colours chosen for each stroke by the synaesthetes was eight times smaller than the test-retest difference shown by the controls, thus supporting the synaesthetes’ claim that different strokes always provoke the same colours.

Next the researchers administered a version of the Stroop test: the synaesthetes and controls were presented with the same swimming stroke photos as before, but this time they were shown with different coloured tones, for example in blue or yellow. The participants’ task was to name the colour. If certain swimming strokes really do evoke particular colours for the synaesthetes then their colour naming ought to have been affected by the precise stroke/colour pairing on any given trial, such that you’d expect them to be quicker if the photo’s colour matched the colour evoked by the stroke shown in the image. That’s exactly what was found – UJ, for example, was 101ms slower when naming incongruent colours versus congruent ones. No such effect was observed for two control participants.

According to the classic view of synaesthesia as cross-wiring between senses, you’d think that swimming-style synaesthesia would require the act of swimming (via proprioception) to evoke a concurrent experience, but this study suggested it was enough to merely activate the concept of the different swim strokes by looking at pictures. This is consonant with past research showing, for example, that letter/number-colour synaesthesia can be triggered merely by imagining the necessary letter or number. Other research has documented synaeshetic experiences devoid of any particular sensory element, including so-called time-unit-space synaesthesia, in which units of time are experienced as existing in particular locations relative to the body.

“Hence, the original name of the presently investigated phenomenon syn + aesthesia (Greek for union of senses) may turn out to be misleading in respect of its true nature,” the researchers said. “The term ideaesthesia (Greek for sensing concepts) may describe the phenomenon much more accurately.” For more detailed discussion of how, when and why synaesthetic triggers and their concurrent experiences are acquired, it’s worth checking out the full-text of the article.

ResearchBlogging.orgNikolić, D., Jürgens, U., Rothen, N., Meier, B., and Mroczko, A. (2011). Swimming-style synesthesia. Cortex, 47 (7), 874-879 DOI: 10.1016/j.cortex.2011.02.008

This post was written by Christian Jarrett for the BPS Research Digest.

Why psychologists study synaesthesia

Finn Toner provides the latest in our ongoing series of guest features for students. Finn is currently reading an MSc in Mental Health Studies at the Institute of Psychiatry; he blogs at Musings.

Synaesthesia is a condition in which the stimulation of one sense consistently gives rise to an automatic experience in a different sensory modality. These ‘sensory blendings’ are experienced by only a minority of the population, but there have been many famous synaesthetes, especially within the art and music world; for example, Thom Yorke from the band Radiohead apparently ‘sees’ certain musical sounds as colours. The condition is not only interesting in its own right, but several recent findings demonstrate that the study of synaesthesia has the potential to inform our ideas about normal cognition.

It has recently been demonstrated that synaesthetes have unusual neuronal wiring. Using an imaging technique called diffusion tensor imaging, Romke Rouw and Steven Scholte demonstrated that grapheme-colour synaesthetes (graphemes are letters or numbers) have more neuronal connections between a variety of brain areas traditionally associated with visual perception, such as the temporal cortex and fusiform gyrus. This suggests that synaesthesia might result from this abnormal cross-wiring.

However, it has also recently been demonstrated that a transient grapheme-colour synaesthetic experience can be induced in non-synaesthetes, who presumably lack such additional neural connections [pdf]. Using a hypnotic suggestion technique, which is thought to influence the level of neural inhibition, Roi Cohen Kadosh and colleagues reported that the perceptual experience of control participants matched those of congenital synaesthetes. This suggests that synaesthesia might result from the disinhibition of a normal perceptual process; a likely candidate mechanism in this case is disinhibition of feedback, whereby grapheme-induced activation of a polysensory neuron could result in sensory ‘leakage’ back along the colour perception pathway, and result in the sensation of coloured graphemes. Indeed, such a process could foreseeably happen in a brain area such as the superior temporal sulcus, which is considered an important multi-sensory nexus.

These apparently contradictory findings provide support for the respective traditional theories of synaesthesia – wiring vs. disinhibition – the debate between which has yet to be resolved. However, findings like these also act to emphasise both that we should consider the brain as a functionally interactive and parallel network, and that the resulting neural processes can act in both a bottom-up and top-down fashion. This interactionist perspective on cognition is in stark contrast to the initial Input–Process–Output models proposed at the start of the cognitive revolution.

Specific unusual cases of synaesthesia can also provide interesting insight into normal cognition. In 2007, Daniel Smilek and colleagues reported the case of participant TE, for whom graphemes are experienced as having individual personalities. In an attentional task, they demonstrated that TE fixates significantly longer on graphemes with a negative personality; this implies that she may have difficulty in disengaging her attention from negative graphemes. This example of how synaesthesia can influence overt attention demonstrates that the boundary between the cognitive processes of perception and attention is blurry, again contradicting traditionalist views of cognition.

A final issue is the degree to which synaesthesia is ‘normal’. Consider the correspondence between smell and taste: most of us experience a blending of these senses to create the experience of flavour. It is currently debatable as to when such perceptual integration is ‘normal’ or when it is ‘synaesthetic’ – perhaps we are all synaesthetes to a certain extent!

How common is synaesthesia among children?

For the first time, psychologists have documented the prevalence of a form of synaesthesia – the condition that leads to a mixing of the senses – in a large sample of children. Over a twelve month period, Julia Simner and colleagues tested 615 children aged six to seven years at 21 UK schools and conservatively estimated that 1.3 per cent of them had grapheme-colour synaesthesia, in which letters and numbers involuntarily trigger the sensation of different colours.

“[This] implicates over 170,000 children age 0–17 in the UK alone, and over 930,000 in the USA,” the researchers said, “and suggests that the average primary school in England and Scotland (n = 168 pupils) contains 2.2 grapheme-colour synaesthetes at any time, while the average-sized US primary school (n = 396 pupils) contains 5.1.” Inevitably, the prevalence for synaesthesia as a whole, considering all the sub-types, would be even higher.

A hall-mark of grapheme-colour synaesthesia is that the colour triggered by a given letter or number is always the same – a fact the researchers exploited to identify the condition in school children.

Indeed, when asked to associate letters with colours, the children identified as synaesthetes showed more consistency over a 12-month-period than the other children did over a ten second period!

The study also showed how synaesthetic associations develop over time. The children with synaesthesia had an average of 10.5 reliable grapheme-colour associations when first tested aged six to seven, compared with 16.9 when tested a year later.

“It is not known whether the developmental pattern shown by our synaesthetes (i.e. 6.4 new coloured graphemes per year) represents a linear acquisition, or whether greater gains are made in later years,” the researchers said, “…our lab is currently tracking the development of this group to follow their transition into adult-like consistency.”

Link to earlier Digest items on synaesthesia.

ResearchBlogging.orgJ. Simner, J. Harrold, H. Creed, L. Monro, L. Foulkes (2008). Early detection of markers for synaesthesia in childhood populations. Brain, 132 (1), 57-64 DOI: 10.1093/brain/awn292

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

A touch emotional

Researchers have documented a new form of synaesthesia – the brain condition that leads people to experience a crossing over of the senses.

While synaesthesia often involves letters or sounds triggering the perception of specific colours, celebrated brain scientist V.S. Ramachandran and his colleague David Brang have identified two young women who experience strong emotions when they feel the touch of certain fabrics or textures.

For 22-year-old AW, for example, the feel of denim provokes a powerful sensation of disgust. The researchers say their discovery provides further support for the idea that synaesthesia is caused by abnormal connections in the brain, rather than being a simple case of associative learning, as others have suggested.

As well as denim triggering disgust, AW also experiences perfect contentment and happiness at the feel of silk, guilt in response to sand paper, embarrassment for wax, and humour at the feel of ridged plastic, to name but a few of her touch-emotion combinations. Meanwhile, 22-year-old HS feels creeped out by contact with a textured glove, disgust at wax and fleece, disappointed by corduroy but calmed by ridged plastic. “Both individuals enjoy the freedom and ease of simply touching a ‘positive’ texture after experiencing a negative emotion” caused by a bad day or a fight, the researchers said.

Curiously, AW experiences different emotions depending on whether she touches a texture with her hands or feet (contact with other body areas triggers little or no emotion). The researchers said this shows that the phenomenon isn’t simply a case of AW having come to associate certain materials with specific emotional experiences earlier in life. HS only experiences her touch-based emotions via her hands.

Filming of AW and HS by hidden video camera as they touched various textures showed that their facial expressions consistently matched their emotional reports. Recording of the sweatiness of their fingertips (a physiological indicator of emotional reactivity) also supported their claims. The same wasn’t true for 18 normal control participants. Moreover, AW and HS’s emotional reports stayed consistent when tested again up to 8 months later, even if the specific language they used changed.

Ramachandran and Brang believe the tactile-emotional synaesthesia they’ve documented is caused by heightened connectivity between the parts of the brain responsible for our sense of touch (the somatosensory cortex) and for emotion (the insula). The more subtle categories of emotion, such as jealousy and guilt, might be related to enhanced connectivity with the front of the brain.

ResearchBlogging.orgV. S. Ramachandran, David Brang (2008). Tactile-emotion synesthesia Neurocase, 14 (5), 390-399 DOI: 10.1080/13554790802363746

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

When castanets taste of tuna

Words have sensory connotations to most of us. The word leathery really does feel …well, rather leathery. But to some synaesthetes – people who experience a cross-over of the senses – such analogies are literal and can relate to tastes. That is, certain words cause them to experience a given taste each time they’re encountered. Now Julia Simner and Jamie Ward have shown that this perceptual association seems to be triggered by the meaning of those words – to the concept they represent – rather than by the letters and syllables that they’re formed from.

Simner and Ward demonstrated this by provoking a tip-of-the-tongue state in six synaesthetes. The participants were shown pictures of unusual objects – such as castanets (the Spanish percussion instrument) or a platypus – and in those instances where they indicated they were familiar with the object, but just couldn’t think of the word, they were asked to say whether they were experiencing any kind of taste sensation.

Of 89 such tip-of-the-tongue states that were experienced by the participants, 15 were also accompanied by a taste sensation. For example, one participant tasted tuna when she was presented with a picture of castanets. Later the participants were told the names of the objects, and they confirmed that these words elicited the same taste experience they had reported when in the earlier tip-of-the-tongue state.

When in that earlier state, the participants recognised the picture, but couldn’t currently identify the word for it, or any of the identifying word’s letters or syllables. This strongly suggests it was the concept that was responsible for the taste sensation, and that words normally trigger tastes in the synaesthetes by virtue of the concepts they represent.

The researchers said these perceptual-conceptual associations are likely to be present in everyone but are exaggerated in lexical−gustatory synaesthesia.

Simner, J. & Ward, J. (2006). The taste of words on the tip of the tongue. Nature, 444, 438.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Link to supplementary information on methods (pdf).

"How sour sweet music is…"

“How sour sweet music is…” Shakespeare wrote in his play Richard II “…when time is broke and no proportion kept!”. The musician known to researchers as E.S. can probably sympathise with this quote more than most – she consistently experiences specific tastes, like salt or bitterness, when she hears certain pairs of musical tones. This cross-talk between the senses is called synaesthesia, although it is a rare form. Most synaesthetes experience different colours when they hear sounds or see certain numbers/ words.

Doubters have suggested people with synaesthesia are making it up, or that they have a vivid imagination. But scientists at the University of Zurich tested E.S. on a version of the Stroop task and found evidence that what E.S reports is real. E.S. was able to identify musical tone-intervals faster than five control musicians when researchers applied to her tongue the taste that she normally experiences with a given tone-interval. Yet she was slower than controls with incongruent tastes applied to her tongue. In contrast, the different tastes didn’t affect the control musicians’ performance.

“This demonstrates that synaesthesias may be used to solve cognitive problems”, Gian Beeli and his colleagues said.

Moreover, when the researchers presented E.S. with single taste-related words (rather than applying actual tastes to her tongue), they had no effect on her tone-interval Stroop task performance – thus suggesting strongly that the synaesthesic effect was sensory, not conceptual, and occurred via cross-talk between her auditory and gustatory senses.

There is a downside for E.S. though. According to New Scientist magazine, her synaesthesia affects her musical choice – for example, Bach’s music is a favourite because it’s particularly creamy.

Beeli, G., Esslen, M. & Jancke, L. (2005). When coloured sounds taste sweet. Nature, 434, 38.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.