I'm working on designing an icon set and experimenting with a few different styles. One style would involve every icon being the same color. However, color is really good at differentiating things like a soft warning (yellow) and a more urgent warning (red).

I wanted to experiment with the idea of using shapes to convey different degrees of hazard. The audience for the project will likely stay in the States, so I don't think I need to anticipate Eastern vs. Western clashes or that sort of thing. Consider the following (really basic) example:

Exclamation mark inside different shapes: circle, diamond, square, triangles, octagon

My perception of shapes is informed by road signs, so I personally feel like the diamond and triangle shapes feel more "alert"-like. The octagon obviously says stop, but it's not very distinct from the circle. The circle feels softer than the square, but that's about it.

Semiotics is not my field, so this link about general research didn't mean a whole lot to me. This question about traffic light shapes was an interesting find, but I don't know how universal it is (I'd never seen anything like that before).

So, do basic polygons carry hazardous connotations (or any other connotation, really)? If so, what's the basis...anything other than road signs?

5 Answers 5


With the little research I could find, there are primarily three polygons which are used in signs for hazards which are :

  • Triangle : Usually used for caution
  • Diamond : usually used to denote Warnings
  • Octagon : Used to denote danger.

To quote from the article I am referencing :


enter image description here

Here is a example of it being used in real life as picked up from the British Columbia Pesticide site

enter image description here

That said this shapes themselves are not an indicator of a hazard or a dangerous condition but the symbol or sign put inside them is what defines the actual meaning. For example, you could put a smiley face inside the octagon and I doubt anyone is going to associate that with danger.

That said, I strongly recommend reading this excellent article about the symbolism of shapes and where they are generally used and their connotations with regards to culture

  • 3
    This is the result of shapes creeping out to be a de-facto standard after the Vienna convention on traffic signs. Commented Jul 1, 2013 at 20:27

I would argue that the shape itself has no (or at least very little) meaning. It is the color and the secondary symbol (exclamation mark vs. question mark) that provide the context. Any of the icons in your question are an equally reasonable choice for conveying "warning" or "caution".

Even Microsoft's Standard Icons reuse the same shapes for both the most and least severe messages: Microsoft Standard Icons


There is Graphical symbols — Safety colours and safety signs international standard.

safety signs

Having small set of easily recognized symbols such as circle, triangle and square you should use colors to increase your graphical symbol alphabet. So don't rely just on shape!

Also there is document from Industrial Accident Prevention Association, which contains description:

enter image description here

  • Any mention of the diamond shape?
    – rk.
    Commented Jul 2, 2013 at 19:47
  • 1
    Diamond shape is used for dangerous goods. Commented Jul 3, 2013 at 2:55

According to Golan Levin's presentation, the "father" of Gestalt psychologist W. Köhler already in 1927 conducted studies that empirically associated edges with rough sounds and curves with soft sounds. Some of the images and sounds he used are in the image below. Possibly that might map to a sentiment of roughness or softness in general.

enter image description here

My personal experience from speaking some languages and from the people I casually ask is that in most languages hazardous words have rougher sound and soothing ones have softer sound. Maybe this is a direction where you could look at.


Color is by far the most important indicator but some males are red-green color-blind, so shape is a useful secondary indicator. As others have suggested, use the color-shape conventions of road signs because everyone is familiar with those.

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