Tag Archives: synesthesia

Lookin’ Sharp Kiki

My roommates and I have set a routine during our 5-week Paris study abroad trip. Every day we leave our apartment at the 15tharrondissement(district) and take the metro to the 11tharrondissement. We make our way to the boulangerie. With croissants and coffee in hand, we walk to class.

Last night, as I was trying to fall asleep, I thought of tomorrow’s usual croissant breakfast. It was then that I realized that when I thought of the word croissant I thought of a crescent shape. Whereas the thought of an éclair was associated  with an oblong shape. A mille feuille had a rectangular shape. Were these associations random?

Image of éclairs, croissant, and some other pastries including croissants, respectively.

Take a look at the two shapes presented below, which one would you associate with the word boba, and which with kiki?

Image from Ramachandran and Hubbard 2001 bouba-Kiki experiment; the shapes that they presented to their participants.

I bet you would choose the one on the right to be bouba and the one on the left to be kiki. How did I know? As it turns out, we have a bias towards associating certain words with shapes irrespective of language and age.

Researchers studied individuals with synesthesia, which is a condition of blending sensory experiences with each other (Ramachandran and Hubbard, 2001). For example, someone hearing a C note would associate it with the color blue. However, these researchers expected that the blending of sensory experiences extends to all normal individuals who exhibit synesthesia to a certain extent. Researchers asked participants to identify bouba or kiki to each of the shapes you saw above (Ramachandran and Hubbard, 2001). The results revealed 95% of participants associated the shape on the right with bouba. That is how I knew which association you were going to make. The results of the study, and the choice you just made yourself, depicts that our shape and sound associations are not completely random.  Ramachandran and Hubbard (2001) speculate that the shape of the speaker’s lips—whether they are open and round, or wide and narrow—and the visual perception of an object being sharp or rounded are represented by parts of the brain that are connected with one another. Thus, there are connections between the sensory brain areas, brain areas related to perception, and the motors brain areas, brain areas related to movement. Other researchers also examined the effect of vowel and consonant shapes on the meaning of the random letters represented (McCormick et al. 2015). These findings suggest that there are not only connections between our brain areas related to shape and sound, but also connections between sounds and our understanding of the meaning associated with them.

This makes me wonder, would someone who is not an English speaker still match the shape on the right with bouba?

As both an English and Arabic native speaker, I have realized that I chose the shape on the right to be bouba because the “b” in both English and Arabic represents a softer sound, which would be associated with the rounder shape. However, do people who have not been influenced by the English language still associate the same shape with the sound?

Researchers found that indeed non-Westerners, who live in Himba of Northern Namibia, a remote population isolated from Western influence and written language exhibited shape-sound associations when presented with bouba and kiki (Bremner et al., 2013).

Looking at the identification made by participants above and my own identification of the two shapes as a twenty-year-old. I begin to wonder, as a child, would I still have chosen kiki to be the shape on the left?

Image from Maurer et al. (2006) experiment; the images and words that they presented to their participants.

Maurer et al. (2006) studied the bouba-kiki paradigm on 2.5-year-old children comparing them to adults. The researchers looked at the effect of age in the bouba-kiki phenomenon and whether it influences learning of language. The experiment consisted of a pair of rounded and pointed shapes and 2 random letters that the children identified with each of the shapes. There were four different trials. The results showed that regardless of age, participants matched rounded shapes with words that had rounded letters (ex. B, O), while the pointed shapes were matched with unrounded letters (ex. K, T). Thus, this depicts that shape-sound mapping occurs in children and may influence language development. This means that as a child, I would have still chosen the same shapes to represent bouba and kiki. However, there is a drawback to this study as children at 2.5 years have already learned how to say words. Hence, the possibility of vocabulary influencing their shape-sound mapping cannot be eliminated. Therefore, no direct conclusions can be made about its implications on the evolution of language. The researchers strengthened their conclusion by not only including bouba and kiki words and shapes, but also testing other shape and word associations. Thus, emphasizing that we are biased towards shape-word associations, which are independent of age.

So, shape-sound associations impact our categorization and representation of things. Now, when I think about croissants being crescent shaped and éclairs being oblong, I question: is my vocabulary affecting my word-shape association? This is something that remains unknown. Thus, future studies need to look at whether infants who have not yet learned how to speak would have the same shape-sound associations. Our insight that shape-sound associations are neither language dependent nor age dependent emphasizes that this phenomenon could be a part of the evolution of language. Further research is needed to explore this aspect of language.



Bremner, A. J., Caparos, S., Davidoff, J., de Fockert, J., Linnell, K. J., & Spence, C. (2013). “Bouba” and “Kiki” in Namibia? A remote culture make similar shape–sound matches, but different shape–taste matches to Westerners. Cognition126(2), 165-172.

Maurer, D., Pathman, T., & Mondloch, C. J. (2006). The shape of boubas: Sound–shape correspondences in toddlers and adults. Developmental science9(3), 316-322.

McCormick, K., Kim, J., List, S., & Nygaard, L. C. (2015, July). Sound to Meaning Mappings in the Bouba-Kiki Effect. In CogSci (Vol. 2015, pp. 1565-1570).

Ramachandran, V. S., & Hubbard, E. M. (2001). Synaesthesia–a window into perception, thought and language. Journal of consciousness studies8(12), 3-34.

Image References:

Image 1: https://bfmbusiness.bfmtv.com/entreprise/convertir-les-americains-a-la-patisserie-francaise-l-objectif-de-cette-chaine-coreenne-971961.html

Image 2: Figure from the paper: Ramachandran, V. S., & Hubbard, E. M. (2001). Synaesthesia–a window into perception, thought and language. Journal of consciousness studies8(12), 3-34.

Image 3: Figure from the paper: Maurer, D., Pathman, T., & Mondloch, C. J. (2006). The shape of boubas: Sound–shape correspondences in toddlers and adults. Developmental science9(3), 316-322.


Sandpaper is to Ruki as Satin is to Lula

In class we discussed the phenomenon that is the bouba/kiki effect. This study was developed in 1929 by Kohler but has been repeated with different variations since then. Try it yourself here: which of these shapes is bouba and which is kiki?

Which is bouba and which is kiki?

You probably said the sharp angular shape was kiki and the bubbly curvy shape was bouba, right? You’re not alone, when this study was repeated by Ramachandran and Hubbard in 2001, 95% of people picked the left shape as kiki and the right shape was bouba (Ramachandran and Hubbard, 2001). This experiment contributed to the ongoing science of understanding synesthesia. Synesthesia is a condition where a person experiences sensations in one modality when another modality is stimulated (Ramachandran and Hubbard, 2001).

How someone with grapheme-color synesthesia might perceive the alphabet and numbers

A modality is a way of experiencing something; for example if a person with synesthesia heard the note C, he/she may associate that note with the color red. There are many types of synesthesia, the most common being grapheme-color synesthesia during which a person correlates a letter or number with a specific color.

Since the original bouba/kiki experiment, many studies testing a variety of associations between different modalities have been published. In one paper, the authors Etzi et al. study the association between nonsensical words and physical touch. Twenty five subjects in their early 20’s, who were blind folded and wore ear plugs, were asked to describe and rate the experience of having different textures rubbed on their arms. Samples of different textures included cotton, satin, tinfoil, sandpaper, and abrasive sponge. The hairy part of the skin was targeted since there is evidence that a certain type of fiber only found in hairy skin is associated with feelings of pleasantness (Loken et al., 2009). Participants were then asked to rate the tactile simulation with a variety of nonsensical words, adjectives, and emotional descriptions. Scales of nonsensical words such as kiki vs bouba, ruki vs lula, and adjectives such as loud-quiet, beautiful-ugly, feminine-masculine were used. When describing emotion, participants were presented with an emotion and asked to rate whether the texture represented this emotion “not at all” or “very much”. Analysis of results show that rougher materials such as sandpaper and abrasive sponge were rated as more “kiki”, “ruki”, and “takete” while smoother materials such as satin were rated as more “bouba”, “lula” and “maluma” (Etzi et al., 2016). This may be explained by the fact that phonemes /t/, /k/, /p/, are “strident and plosive” consonants while /l/, /m/, /n/ are sonorant and continuant consonants (Nielsen and Rendall, 2013). Another interesting result was that smoother textures like satin and cotton were described more as “feminine” and “beautiful” while rougher textures like sandpaper were described as “masculine” and “ugly” (talk about gender norms am I right?) (Etzi et al., 2016). Overall, this study concluded that there is an association between nonsensical words and perceptions of tactile textures.

While this study provides more evidence into cross modality correspondences, there is a weakness. Hairy skin was targeted for stimulation since there would be greater fiber response; however, people have different amounts of body hair which may affect the tactile stimulation experience between participants, skewing the results. There are still many different cross modal associations that have yet to be studied that would be interesting future experiments. By understanding the different associations, we are able to better understand just how interconnected the brain is.

The significance of cross modal associations is more ubiquitous than you might think. When we go to the store to pick up groceries and maybe a bottle of wine, activation of our different senses gives us subconscious reactions to these different stimuli. The shape of that one wine bottle may be associated with harsh, rough, loud words while the shape of another may be associated with soft, flowy, harmonious words. The words that we associate with that shape will influence which bottle we decide to buy.

Different wine bottle shapes

The decisions we make when shopping are based on product design and how we perceive an object from our different senses. So next time you’re shopping for wine, instead of going for the cheapest option, examine the shape, the texture, and feel of the bottles. Introspect and ask yourself, how does the design really make you feel?


Etzi, R., Spence, C., Zampini, M., & Gallace, A. (2016). When sandpaper is ‘Kiki’ and satin is ‘Bouba’: An exploration of the associations between words, emotional states, and tactile attributes of everyday materials. Multisensory Research, 29(1-3), 133-155.

Hanson-Vaux, G., Crisinel, A.-S., & Spence, C. (2013). Smelling shapes: Crossmodal correspondences between odors and shapes. Chemical Senses, 38(2), 161-166.

Löken, L. S., Wessberg, J., McGlone, F., & Olausson, H. (2009). Coding of pleasant touch by 477 unmyelinated afferents in humans. Nature Neuroscience,12, 547-548.

Nielsen, A. K. and Rendall, D. (2013). Parsing the role of consonants versus vowels in the 510 classic Takete–Maluma phenomenon, Can. J. Exp. Psychol. 67, 153–163.

Ramachandran, V. S., & Hubbard, E. M. (2001). Synaesthesia- A window into perception, thought and language. Journal of Consciousness Studies, 8(12), 3-34.

Picture 1: https://en.wikipedia.org/wiki/Bouba/kiki_effect

Picture 2: http://synesthesia-test.com/synesthesia-test

Picture 3: https://chwine.com/tasting-room/decoded-intro-to-wine-bottle-shapes/

Hallucinations or Chromesthesia?

When we visited the Musée D’Orsay a couple of weeks ago, I was disappointed to hear that The Starry Night painting by van Gogh was at another exhibition; I had looked forward to the opportunity of seeing it in person. Although this was not possible, this past weekend we travelled to Arles, the town where van Gogh lived most of his life. It was a wonderful experience to walk around the areas where he painted his most famous works! Vincent van Gogh, one of the most famous painters from the mid-1800s, was also a man who lived a struggling life. Being somewhat of an outcast, he was ostracized by his community leading him to live a life of loneliness. Over the years, he spiraled into a routine of drinking absinthe that eventually led to the deterioration of his health. He was diagnosed with epileptic seizures and lived in and out of an asylum in Arles, France. Few know that he did his most famous works while he was suffering from these manic and depressive episodes. Seeing as how we have learned so much about him and even visited his hometown, I decided to look more into his medical diagnosis.

Starry Night: One of Vincent van Gogh’s most famous paintings

When you look at The Starry Night, you probably wonder how is it that van Gogh was able to see those colors in the sky when you can only see dark shades of blue at night. There are various theories as to why he decided to paint it that way, but one of those theories was that van Gogh had synesthesia. Synesthesia is a condition when stimulation in one sense automatically leads to sensations in another sense (Bradford 2017). For example, a person might see a letter and automatically associate it with a color. In the case of van Gogh, there is some evidence that points to him having chromesthesia. Chromesthesia is a subset of synesthesia in which certain sounds are associated with colors. “Vincent Van Gogh explained in his letters that for him, sounds had colors and that certain colors, like yellow and blue, were like fireworks for his senses” (Katie 2018). Could it be that he had synesthesia.

A famous cafe in Arles, France painted by van Gogh

Synesthesia is still a widely unknown occurrence. There are 6 regions in the brain, primarily in the motor and sensory cortex, where higher activation levels are observed, V4 (involved in color perception) being one of them (Rouw et al. 2011). For this reason, there are two differing hypotheses as to how it arises, one of them being that there is somehow a disinhibition when relaying back sensory information to the different brain areas, meaning that essentially anyone has the potential to develop synesthesia. The other theory is that there is a cross-activation mediated through white matter pathways that occurs between the different sensory cortex areas; this is something you are born with, so only those people are able to develop it.

To test this out, researchers performed a visual imagery task to induce synesthesia in a group of individuals (Nair and Brang 2019). They were put in a dark environment to simulate visual deprivation and were then asked about the shapes of multiple letters through audio. The results show that there was significantly more visual imagery when a sound was presented right after the audio recording. The fact that it took approximately 5 minutes to induce these sensations points to the theory that everyone is born with the capacity to be synesthetic, but it only appears when one of the other senses is deprived.

Could this be what van Gogh was experiencing? In a 2016 case study, they describe how a 20-year-old woman who was diagnosed with social phobia and schizophrenia due to her avoidance of social groups and claims that she could see colors when she heard sounds. The doctors thought that she was suffering from hallucinations. In reality, she had savant abilities and synesthesia. To have someone be misdiagnosed only a couple of years ago, makes you wonder if maybe the doctors missed something when diagnosing van Gogh. At a young age, when he took piano lessons, he described the experience as overwhelming because each note was associated with a different color He was disregarded and His teacher believed him to be insane and wouldn’t allow him to continue the lessons (Taggart 2019). Could it be that he was never understood because he did in fact think distinctly due to his ability to perceive the world in a different way? A question that may never be answered, but could give us a little more insight into one of the greatest artistic minds of that time. Maybe for van Gogh, the sky was in fact joyous and explosive, not just a simple color.


The cafe that inspired van Gogh’s painting


Bradford, Alina. “What Is Synesthesia?” LiveScience, Purch, 18 Oct. 2017, www.livescience.com/60707-what-is-synesthesia.html.

Bouvet L, Barbier J, Cason N, Bakchine S, Ehrlé N (2017) When synesthesia and savant abilities are mistaken for hallucinations and delusions: contribution of a cognitive approach for their differential diagnosis, The Clinical Neuropsychologist, 31:8, 1459-1473

Katie. “Vincent Van Gogh and the Power of Synesthesia in Art.” Exploring Your Mind, Exploring Your Mind, 20 June 2018,

Nair A, Brang D (2019) Inducing synesthesia in non-synesthetes: Short-term visual deprivation facilitates auditory-evoked visual percepts, Consciousness and Cognition, 70: 70-79.

Rouw, Romke, et al. “Brain Areas Involved in Synaesthesia: A Review.” Journal of Neuropsychology, John Wiley & Sons, Ltd (10.1111), 16 Sept. 2011

Shovava, and Shovova. “5 Synesthesia Artists Who Paint Their Multi-Sensory Experiences.” My Modern Met, 28 Feb. 2019

Picture 1: https://www.overstockart.com/painting/van-gogh-starry-night

Picture 2: https://en.wikipedia.org/wiki/Café_Terrace_at_Night

Picture 3: https://fineartamerica.com/featured/cafe-van-gogh-forum-square-arles-aivar-mikko.html