According to Chris Solarski’s article, details how all 3d shapes within a game–whether they are figures, environment, or props–begin as one of three basic shapes: circles, squares, or triangles. Each of these shapes are associated with an aesthetic concept:
Circle: innocence, youth, energy, feminity
Square: maturity, stability, balance, stubbornness
Triangle: aggression, masculinity, force.
According to Solarski, we associate these shapes with these aesthetic concepts because of our real-life experience. Imagine one of the three objects above being thrown at you. Instinct will tell you the sphere will not hurt, the cube may if you catch it incorrectly, and the star will hurt regardless. This is based on your early life lessons regarding sharp objects. Those psychological associations let us orient them along, what Solarski calls, a shape spectrum of emotions. We associate curvature with positive feelings and safety and more triangular shapes with negative feelings and danger.