Whoever wants to show his individuality wears black. A black dress or a black suit has a distant effect. Black gives the wearer its dignity or at least unapproachability. The black clothing from the Reformation concentrated the appearance of a person on the face, the center of individuality. The existentialism around 1950 became a fashion phenomenon. The Sartre supporters wore black. As a colour of detachment, black clothing is popular with all groups that place themselves outside the crowd and do not want to adapt. Nozems, rockers or punks: the names change, but the favorite colour remains black.
Heller (1989)

Palettes of 4 similar-hue colours were rated as more pleasant (harmonious) than dissimilar-colour palettes.
Sanocki & Sulman (2011)

Lakoff and Johnson (1999) saw that there are many proverbs and sayings that have to do with form characteristics and emotions. Parallel / equal movement / oneness: togetherness, concomitant, positive, appropriate, power, strong, suitable, assisted, helped. Perpendicular / disunity: wrong, not combining, opposing, less strong, hindering.