Partly to distinguish painting from photography and mass-produced illustrations, and partly to acknowledge the innate two-dimensionality of pictorial art, American painters turned away from figurative compositions in the mid-20th century and embraced abstraction as their mode of expression. To distinguish fine art from mass-produced prints, abstract painters left traces of their handiwork on the canvas, such as paint drips, tape marks, and sloppy brush strokes. These traces, known as “gestures,” gave their paintings a hand-made, authentic quality. Another point of emphasis was the representation of pictorial space. In contrast to paintings dating back to the Renaissance, in which implied space was allowed to expand for a great distance (and in theory to infinity), the squiggles and spots in mid-20th-century abstract paintings were supposed to occupy as shallow a space as possible (and in theory just two dimensions). Art theorists were concerned about the independence of painting as an art form; paintings in three dimensions were too much like sculpture for their taste. A painting should look like a painting, they said, and not like an illusion of volumetric space. The emphasis on flatness was an important reason why painters of the era were reluctant to compose pictures with recognizable objects or human figures—in the real world, objects and figures have volume and occupy three-dimensional space, which is incompatible with a flattened picture plane.
Cole TB. CoupleDavid Park. JAMA. 2015;313(10):992-993. doi:10.1001/jama.2014.11625