Artist Wallisy Kandinsky joined the Bauhaus art movement in 1922. He believed that abstract shapes (the square, circle, and triangle) were associated with particular colors. Before reading on, take a moment to decide: What colors would you associate with these shapes?
The reason I'm interested in this is because I study imagination, and I'm kind of curious: If you ask someone to imagine a square, what color are they going to make it in their mind's eye? I'm also curious because I would like to know what colors are best to use in visual art—if certain colors are better associated with certain shapes, then using those associations (or perhaps deliberately not using them) might result in more compelling art. I explore the psychology of art in my upcoming book (Davies, 2014).
Kandinsky ran a little test on people and found yellow triangle, red square, and blue circle. Later, in 2002, Thomas Jacobsen tried to replicate the experiment and came up with different results: red triangle, blue square, and yellow circle. About half of the participants he polled chose these color associations. He also found that people justified their choices based on real-world objects, such as a red triangle looking like a red warning sign.
I ran my own informal poll in a class I was teaching, and came up with yet different results!
As you can see from the first figures, blue was more commonly chosen color for square, yellow was the most common triangle color, and people really don't agree on the right color for a circle.
What's interesting is that some of these results seem pretty clear—but different people asking at different times get different results.
It could be that there is no context-indepenent answer to this question. A further experiment in 2013 found no relationship at all.
Postscript: These polls were done in my classroom. The "triangle" question was done when there was more time to answer the question, which is why there were so many more respondants. My students voted using polleverywhere.com, and voted with their cell phones.
Jacobsen, T. (2002) Kandinsky's questionnaire revisited: Fundamental correspondence of basic colors and forms? Perceptual and Motor Skills, 95(3) 903--913.