Olfactory-visual synesthesia

Its subtypes, which can occur separately or together, are smell-colour and smell-shape

Image: Pau 365. The smell of a flower, 2018.

This is the visual experience of the smell of a flower in Portugal in 2013. I saw the shape projected in the air because I had hyperosmia at the time, giving me an extremely sensitive sense of smell and causing very strong synesthetic experiences. I normally only perceive the shape of smells in my mind’s eye.”

Olfactory-visual synesthesia is not a particularly common type (according to Sean Day's study, around 6% of synesthetes could have it, suggesting that the prevalence of people who “see smells” is similar to that of people who “see tastes”.) It manifests in two main ways: colour and shape, and a synesthete may experience either just one of these or both of them together. Projector synesthetes, who are clearly a minority, see the shapes or colours physically in front of them when they smell something, while associator synesthetes only see them in the mind’s eye.

Photisms created by smell usually have a spatial location; they can be high or low, for example; they can be clearly vertical, horizontal or diagonal; for some people they have movement: they can rotate, sway, oscillate or jump about, repeatedly expand, replicate, or travel constantly in a certain direction. They often have a major emotional component. For some people with this type of synesthesia an additional tactile sensation is evoked (the shapes are felt in a specific part of the body: hands, arms, chest, etc.), although this appears to be rather uncommon, occurring much more frequently with taste synesthesia than with smell synesthesia.

The visual concurrents are consistent but can be more or less pronounced depending on the person’s olfactory capacity at any given time (our sense of smell has “good days” and “bad days”, as it were) and it can also depend on factors such as the degree of focus on the experience, relaxation or stress, and even mood. For some, colours and/or shapes are triggered by all smells in general, while for others it is more selective and they are only produced by certain types of smells (see the example below of a person who only has concurrents for people and their clothing), or the smells have to be strong, or new and interesting, for example.

People with olfactory-visual synesthesia very often have gustatory-visual synesthesia too, so their colours and/or shapes are induced by smells and also tastes, and in fact they sometimes confuse them as the experience is so similar.


Smells trigger colours, but with no specific shape.

Anti-freeze”, by Corinna in the Gallery of the website Sensequence

The smell of anti-freeze for the windscreen-washer. The smell varies briefly between green and pink; if I smell it for a longer period (e.g. in the car), the green and pink streaks mingle like coloured fog.”

“I remember most accurately scents. We were preparing to move into the house I grew up in. I remember at age 2 my father was on a ladder painting the left side of the wall. The paint smelled blue, although he was painting it white. I remember to this day thinking why the paint was white, when it smelled blue.”

(Source: the synesthete MN, quoted in the book Synesthesia: A Union of the Senses by Richard E. Cytowic, 2002, p44.)


The shapes perceived are geometric figures, simple or complex, or highly idiosyncratic abstract forms, often very complicated and not reminiscent of anything that exists in real life. Some of the most common shapes described are spheres, ovals, lines, curves, blocks or rectangles, spiky shapes, triangles or pyramids, cones or wedges. The shapes often replicate, repeating themselves, sometimes to infinity. They can have colour and/or texture or they can be colourless and without any texture in particular.

(Image: Cuccoteaser, in Reddit/Synesthesia, 2014. "I attempted to draw a few smells.")

“For smells, it's mostly in terms of their smoothness/spikeyness. Some acrid smells are compact and are kinda covered with spikes (vinegary smells), while others have like a single long spike (ammonia). I have a deodorant that kinda just rolls and bobs around inside my nose, without any spikes at all. Most of the time, it's only vague impressions and more complex smells don't have easily identifiable shapes/motions.”

(Source: This post on the online debate platform Reddit/Synesthesia. 2018.)

Smell-colour and shape

Smells evoke coloured shapes.

“Basically, for as long as I can remember, when I eat particular food or smell particular scents (so my taste and smell senses), I seem to sense it in shapes and colours.

Like a certain smell I will experience as a soft, blue circle. Or perhaps a soft triangle.

But I don’t actually see any colours or shapes in my vision. I just feel like that’s what it smells or tastes like.

I essentially just “know” that those scents or tastes is a certain shape and colour (and sometimes just one of the two).”

(Source: This post on the online debate platform Reddit/Synesthesia. 2020.)

I've had this all my life, where the way a person or piece of clothing smells has a distinctive color or shape. Like my friend smells like a white rectangle with green splotches behind it on a black background, or my dad smells orange with a black wave around it. (…) It’s only those certain types of scents.”

(Source: This post on the online debate platform Reddit/Synesthesia. 2020.) 

How gustatory-visual and olfactory-visual synesthesia can help you cook

Some synesthetes have this skill or have been able to cultivate it.

"When I eat or drink something, I always visualise the taste as shapes and colours.
When I'm cooking something, I only need to smell the food, and I know exactly how it looks like. Then I search for missing things or mistakes in those visuals and that's how I know what to add."

(Source: This post on the online debate platform Reddit/Synesthesia. 2019.) 

Smell-shape/tactile sensations (possible olfactory-tactile synesthesia)

I haven’t found any cases where someone has an exclusively tactile reaction to smell, as is the case with sounds in auditory-tactile synesthesia, for example, which triggers sensations on the skin and in different parts of the body that are often only tactile and have no visual component at all. However, I was able to chat online with this interesting person who has smell-shape synesthesia and perceives the shapes in a tactile way, so the tactile and the visual coexist, as often occurs with taste-shape synesthesia but much less frequently in the case of smell-induced synesthesia. In his particular case, he perceives the abstract and geometric shapes as within him, near him or actually touching him: they are “felt” rather than “seen”, although they are sufficiently visual for him to be able to draw them.

(Image: Shpongulate, 2019.)

I notice that I experience the shapes of these smells in my upper body, in my arms, and the edges of the shapes are near my hands. Although I've never really thought about it that way! In one sense the shapes are just "in my mind", but spatially they are close to my body, and effectively standing on me.

It's really interesting to compactify these into visual shapes, because they really aren't JUST visual, it's a multisensory experience with it's own flow of energy that defines what it is."

Source (image and text): This post and comments on the online debate platform Reddit/Synesthesia. 2019.


Go to the page on olfactory-auditory synesthesia (smell-musical notes or sound)

Go to the page on olfactory-tactile synesthesia

Go to the page on smell and memories (not a type of synesthesia)

Go to the page on gustatory-visual synesthesia (taste-colour/shape)

Go to the page on taste-colour synesthesia

Go to the page on taste-shape synesthesia

Go to the page on gustatory-tactile synesthesia (taste-touch sensations)

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