Concept-shape synesthesia. Thought processes-shapes or colour

Some manifestations of these types can also be called "one-shot synesthesia" and "high-production synesthesia" (see below)

Some people refer to the more complex version of this type as "kinesthetic synesthesia"

The term "concept-shape" 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, decision-making, etc. It evokes geometric shapes, lines and other forms and/or dynamic colours as its concurrents, which can often be highly complex and 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 would actually see them physically in space, although this manifestation is extremely rare. When it is regular, consistent and deeply complex it seems to occur in highly intelligent individuals and could be a characteristic of some savants; in this case it is an uncommon type 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 Reddit/Synesthesia. 2019.)

Concept-shape/colour/spatial position (not the most complex type, but with more elements and applying to specific thought processing situations, occurring on an occasional basis and not as a constant thought-processing style):

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 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 Reddit/Synesthesia, slightly paraphrased. 2022.)

The most complex type (this is the habitual thought-processing style of the people who experience it: it happens regularly and is not a one-off occurrence):

"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 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 Reddit/Synesthesia. 2021.)

This account provides a good definition, coining the term “understanding-shapes” to describe the phenomenon:

“With every newly understood concept exists this shape in a dark, three-dimensional space. The colors differ slightly from each understanding and whenever accessing or making use of a newly understood concept, my mind enters through the bottleneck of each shape into the open space that exists above it and contains abstract representations of further, more complex topics that, themselves, can be transformed into one of these understanding-shapes, should I bring myself to understand it, encompassed by that new understanding that leads to it. It's a visual manifestation of these possibilities.”

(Source: This post on Reddit/Synesthesia. 2022.)

“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 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 Reddit/Synesthesia. 2019.)

Where to read more and share experiences
If you have this type of synesthesia or are interested in it and would like to read more people's accounts, share your own experiences or ask a question, check out these two subReddits: /r/concept_synesthesia  and /r/ConceptSynesthesia (the second one is closed to new posts now but still interesting to read).

"One-shot" and "high-production" synesthesia 

Concept-shape synesthesia can sometimes occur in a spontaneous, novel way when a synesthete is faced with a one-off concept affecting their life in some way, obliging them to solve a problem or make a decision, and they might suddenly visualise shapes and colours or even a sort of abstract “landscape” representing these concepts. It is not necessary for the synesthete in question to have regularly had conscious experiences with this type of synesthesia throughout their lifetime for this to occur. The neuroscientists Alexandra Kirschner and Danko Nikolić coined the term “one-shot synesthesia” to refer to this phenomenon, providing several real accounts of it in a notable research study published in 2017. He focuses on the sporadic and original nature of these experiences and the fact that they might occur just once or twice in the synesthete’s lifetime. When they occur regularly and consistently he uses the term “high-production synesthesia”, which is the type described above and referred to as the more complex type of concept-shape synesthesia. Quoting Nikolić in this 2017 study, “High-production synesthesias do not produce surprises for their owners. In contrast, one-shot synesthesias are regularly followed by a surprise, interest, reflection, etc. Prior to the occurrence of one-shot synesthesias, our subjects did not expect those experiences to take place.” You can read the study here.

Examples of “one-shot synesthesia”

This case is taken from Kirschner and Nikolić's study:

“When I had to make a career decision, I was surprised by a synesthetic experience, which I spontaneously called “decision synesthesia”. I had to concentrate on every image very hard because the images were very pale. I would like to describe three of these synesthetic experiences that occurred to me, each only once in my life. One was a thin-walled shoebox with an exhaust pipe, not transparent at all, not changeable. It had a temporal dimension: the present was situated in the middle of the picture; the future extends to the right side. I interpreted this experience as telling me that presumably everything would be all right at the beginning. However, on a long run, I would have felt as if I got stuck in that exhaust pipe. If I were to accept this job offer, I should already start to considering alternatives in the near to middle future.”

(Synesthete J.S.A.)

Here is another case that is interesting for two reasons: firstly because the shape impression perceived is tactile rather than visual, and secondly because it is in response to a very specific concept: as the person who experiences it tell us that “most, if not all, occurrences [have] happened when either a hypothetical/fantasy scenario was being described to me or by me, but perhaps a desire for those situations triggers an object.” This specific feeling causing the tactile perception, rather than a dilemma or decision-making process, and the fact that it appears to be consistent each time a similar feeling is perceived, also mean it could be an instance of emotion-tactile synesthesia.

“For as long as I remember, there would be instances where I hear a word/phrase/sound and I could feel like the pressure required to hold an object of a specific size & weight, without there being an object in my hand. (…) I could only feel the 'ghost' weight but not feel any actual weight.
This doesn't happen very often. (…) I think I had [these experiences] a lot more frequently when I was a child.
I don't think I've ever known what the things are, although usually they're small enough to be held by one hand.
One of my most distinct memories of these experiences is a car ride when my mum was talking about a dream she had, in which I was an architect, and when she was telling me the dream I felt an object similar to the size of an avocado pit in my right hand. The object wasn't the weight of an avocado pit, I perceived it to be a lot lighter and to be an inelastic object. As a kid, there was a point in time when I did want to be an architect, and I remember explaining to either my sister or a friend my vision for my adult life as an architect. (…) When describing my ideal adult life, I remember experiencing a similar, if not the same, sensation in my right hand.

(Source: This post on Reddit/Synesthesia. 2024.)

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.”

Links to some more interesting examples of consistent, complex or "high-production" concept-shape synesthesia:

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.

Related synesthesia types:


The mathematical synesthesias

This page last updated: 19 June 2024


  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"

  3. Well, I have been wondering for about 40 years.... I have been asking my shrink and gp and had researched this before, knowing about synesthesia even. I just found this page. Makes sense now. I have always seen hazy shapes in a volume of no color. Familiar concepts have a more well defined form. Others, not so much. When thinking hard about anything they are more of the process somehow. I think the shapes may be the ways in which ideas are stored so when compared to one another we can tell if they are similar and compatible or if they are not in the same family. That's what I think I see.

  4. I’ve beem seeing time from right to left all my life. Monday is to my right and lower down once I’m in Tuesday, and Wednesday is to my left and down. Hours begin at my feet with 8 AM and end at midnight above my head (the opposite of how people’s daytimers show time).
    I see 3years circling around me loke fat inner tubes. Anesthsia causes me to have vividly colored nightmares which can last several weeks so I always request a spinal or local when possible. I still remember the vividly colored image I saw as a child when I had my tonsils out..back when they were still using ether, but I have permanent full color memories of every anesthesia since then…always a disturbing new one each time.

  5. I was surprised to find that this was unusual! I'm used to finding that I think about things differently from other people, but I had no idea that most people don't have visuals of concepts and ideas! I've always thought of the distinction between abstractions and "concrete" things as being an arbitrary distinction that I didn't fully understand. I am sometimes told that I am being "too abstract", and I have never really understood why people say this. For me, broad concepts have colors, and more specific ideas have shapes that have that color. For example, consciousness is light blue, time is a gentle yellow, suffering is orange, and math is bright white. In terms of more specific ideas, groups (mathematical groups, not the more general idea of a group) tend to be tangles of white lines, numbers are pretty much just white dots, but they still look different from each other, (only significantly different types of numbers look different, but integers, say, are all pretty much different instances of the same thing) thoughts are kind of blue blobs, and moments in time are yellow rectangles. (The further into the past they are the more yellow they are, and the future actually starts to get slightly blue.)