Concept-shape synesthesia. Thought processes-shapes or colour

This could refer to two types of synesthesia, one simpler and the other more complex, where series or sequences of concepts trigger a concurrent of shapes. An example of the more simple type would be perceiving the concept of left as round and right as square, or associating each language with a different geometric shape. The first description below is an example of this type, which does not appear to be very common and is reminiscent of duality synesthesia (stimulus-parity synesthesia, for example, where concepts are either odd or even) but with more than two categories.

The second type, more complex, is triggered by concepts, ideas, information, categories, procedures, thought processes for problem-solving etc. It evokes geometric shapes, lines and other forms and/or dynamic colours as its concurrents, which are involuntarily and consciously perceived visually as the synesthete thinks. In the case of associator synesthetes they only appear in the mind’s eye, while projector synesthetes actually see them physically in space, although this manifestation is extremely rare. When it exists to a very complex degree it seems to occur in highly intelligent individuals and could be a characteristic of some savants; it is an uncommon type in general and has similarities with certain types of mathematical synesthesia.

Here are some descriptions written by people with this type of synesthesia:

Concept-shape (the simpler type):

"Disney is round. Adidas is triangular. I’m triangular. I get along with people who are squares and rectangles. I don't typically get along with rounder personalities. Left handed people tend to be squares. Right handedness (the idea) is triangular."

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

Concept-shape/colour/spatial position (not the most complex type, but with more elements and applying to specific thought processing situations):

These are two recent examples of how some concepts (or categories, perhaps) and basic thought processes/opinions can automatically take the form of shapes and colours. In this case they are concerned with writing and literature and involve the active participation of the synesthete in some way (not just reading). Although they may not be an overwhelming experience, when focused on they become clear and they are very memorable, also helping with the task in hand.

“I have noticed that while writing I see irregular lines and dots projected in the space between the page and me that change configuration, in terms of structure and complexity, in response to how I perceive the quality of my writing. So when I'm re-writing a passage several times, the pattern may shift and generally becomes less dense with fewer elements as my writing improves. If the pattern doesn't change I know it needs more work. I am sure this has been happening for a very long time but I don't normally perceive it consciously. A couple of years ago I suddenly noticed it and forced myself to look right at it. Since then I have been pondering what it could be and thought it must be a visual projection of my thought process.”

(Source: This post on the online debate platform Reddit/Synesthesia. 2022.)

“We were putting a book together with stories/accounts written by different people and it was my job to decide on the order they should go in. Some seemed light blue or white and floaty while others were brown and close to or rooted in the ground, and just one was black. These colours and spatial positions were very memorable since the first reading and so it was easy to balance and vary their order in the book, but after having realised this was happening I decided to read them again and focus more on the colours they were producing. That was a beautiful chromatic experience. I discovered that the factual, less substantial, sometimes confusing or not too interesting stories went from light blue to white, even being a flat square or rectangle that floated up and away the more this was the case, while the action-packed, exciting ones with a more gripping style were different shades of dark brown and sank by their own weight! So those colours and shapes are something I'll be looking out for now.”

(Source: my comment in response to the same post on the online debate platform Reddit/Synesthesia, slightly paraphrased. 2022.)

The most complex type:

"Ok so basically upon hearing or thinking of a concept or issue, I will see it in my head as different coloured shapes on a black plane that interact with each other and having conceptual meaning to me which I can then verbalise by watching the interactions between the shapes. It’s like if I see a blue circle wrap around and engulf a red triangle, I now know and understand the concept."

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

“I see complex, multidimensional, topological forms at all times, and they’re more pronounced when I’m in deep thought. It’s like I’m literally seeing the pure logic that underlies everything—math, philosophy, everything. It’s really beautiful and it’s been there for my entire life. If I need to go back to a thought, it’s like the shape will shift back to show the specific point where that thought was recorded.

My shapes have too many dimensions to perceive their exact edges, but somehow I know where they are. There’s no way I could draw them, and even attempting to feels like a horrible insult to myself.”

(Source: This post on the online debate platform Reddit/Synesthesia. 2021.)

“It’s a little hard to describe, but my synesthetic experience is basically that thoughts have a sort of geometry to them. Pure logic has a beautiful crystalline structure, my own thoughts are kind of modular and pieces get shuffled around until I find the “right” shape for that thought (I reach a conclusion and can communicate it in words). Whenever I’m hearing/reading a new thought process for the first time, it’s like I’m watching a simple form develop into gradually more complex shapes until it “freezes”, either because the thought is finished or I can’t understand the remaining mental steps. Also I guess I should note that I’m an associator instead of a projector, so I only see these shapes in my mind’s eye instead of visually laid out in front of me.”

“I can qualitatively describe (the shapes of abstract ideas) usually, but I could never represent them visually. For example, I know that pure logic is crystalline and extends so far vertically that it goes beyond my mental “field of vision” in both directions. And I know that the Nichomachean ethics is a sort of spheroid that develops into a horizontal tube and that Lovecraft’s cosmicism is a circular disk with a weird topography resting on top. One of my best friend’s minds is similar to logic but more finite and arranged in a kind of cube-ish way, but Jordan Petersen is a MASSIVE sphere of points with all kinds of connections flying between them.”

(Source: This post (first quote) and this comment (second quote) on the online debate platform Reddit/Synesthesia. 2021.)

“It turns out that ideas and concepts taking the form of very-solid black outlines of cubes is not a part of the typical human experience. (…) They either speed or float past. They're large, about a metre in width and 0.5 metres in height, and are see-through but for their (very thin!) outline and a possible image associated with them that's inside the rectangular prism shape.

(…)  They're involuntary, my mind's eye just generates the images unprompted.

As a 'hello' to this community, despite how short my stay might be, have a horrible artistic rendition of a 'thought tornado' that I see roaming around my school sometimes."

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

More examples:

This conversation in a post in Reddit/Synesthesia (2021) also has some very interesting examples of these visualisations.

This 2016 article in The Atlantic magazine, What's It Like to See Ideas as Shapes?, is about the app designer Jonathan Jackson: “Every person he meets, every sentence he reads, and every decision he makes are presented as data points on a kind of continuously moving mental scatter plot, creating figures he compares to constellations.”

And this article by Maureen Seaberg (2015) describes how Bosnian diplomat Mo Sacirbey is often helped in his negotiation processes by the geometric forms and symbolic additions of figures he visualises as part of his synesthesia.

Thought processes-colour

(Painting by Emily Holt)

“This is a self-portrait” says Emily Holt. “My paternal grandma & I think in abstract colors that have textures & movements. My colors are always there and no one color expresses a particular thing or feeling. In my family these ways of thinking are normal.”

Related synesthesia types:


The mathematical synesthesias

This page last updated: 6 January 2022


  1. Wow I can finally find it. I can see other people's concepts, worldviews, or personalities, and I can also see my own. Seeing smells and sounds, see the picture overview of a story, see the order of numbers and letters in space. All are very complex images. There are some pictures where I feel the texture of it. Feel the properties such as flexibility or hardness.....

  2. this is so enlightening and I feel so seen!! This is the way my mind works and the way I organize thoughts in my head!!! I file away thoughts as shapes, and when I pull them out again, they intertwine and mold and shape new shapes. I didn't know this was so common! I didn't know how to put it into words because I thought I was stupid for thinking that "I have a special way of thinking"