Angulated: grey 18%, black 18%, silver 15%, ….
Heller (1989)

“In a 1921 study conducted by the Swedish psychologist Helge Lundholm, subjects were asked to draw lines representing a set of emotional adjectives. While angular lines were used to depict adjectives like hard, harsh and cruel, curved lines were the popular choice for adjectives like gentle, quiet and mild. Over the years, other studies trying to associate feelings with types of lines have corroborated Lundholm’s findings.

Typography has been the target of a similar analysis. A study conducted in 1968 by psychologists Albert Kastl and Irvin Child indicated that people associate positive qualities like ‘sprightly’, ‘sparkling’, ‘dreamy’, and ‘soaring’ with curved, light, and possibly sans-serif typefaces. This could in part explain, to many graphic designers’ frustration, the wide-ranging popularity of the Comic Sans MS typeface.”

Lima, M. (2017)

Angularity, as with a square stone, is a characteristic of the past versus roundness, the wheel, as a symbol of the future.

The modernist architecture of the last century (1930-1960) was an architectural movement or architectural style based upon a functionalist idea with an embrace of minimalism and a rejection of ornament. The use of round shapes was a style characteristic. It was a radical break with the past and a view to the future.

De La Warr Pavilion, Bexhill. 1935, Architect/Designer: Mendelsohn & Chermayeff. Source: http://flickr.com/photo/53921762@N00/1986171763

In images depicting the future, futuristic planes etc. the artists show a preference for round shapes.

Artist Tim Hildebrandt painted the rounded buildings of his future city yellow. Underneath the future he draws the angular past in a roman temple architecture. The man in the foreground points to the right, where the future lies.

(Michiels, I. editorial)

Square/rounded has an important influence on the function of the size of an angle. Rounded corners are experienced more cheerfully, while straight angles are perceived as more serious (Poffenberger en Barrows, 1924). Round and square are also related to activation. Roundness in parts of utensils or interfaces can indicate a button, where activation is needed. Sharp roundness can therefore trigger alertness and induce action.