Early neuroaesthetic writings in the late 1990s by Zeki and University of California, San Diego, neuroscientist Vilayanur Ramachandran identified parallels between an artist’s approach to her visual world and her brain’s processing of visual information. Light entering our eyes is segregated into a number of elemental properties, such as luminance, color, and motion, that are processed in different visual centers in our brains. At the turn of the 20th century, artists played with these elements in their artwork. For example, the French artists Henri Matisse and André Derain highlighted color to express emotions, and the American sculptor Alexander Calder isolated visual motion in his mobiles (below), whose suspended components were delicately positioned to be moved by air currents or motors.
American sculptor Alexander Calder isolated visual motion in his mobiles, whose suspended components were delicately positioned to be moved by air currents or motors.
Black and Blue | Alexander Calder, 1975 | © LUKE MACGREGOR/REUTERS/CORBIS
Artists often depict mental representations of an object rather than its physical form. Their renditions do not adhere strictly to the light, shadow, and color properties of objects in the physical world, yet they appeal to us. Shadow contours are too fleeting and changeable to provide reliable information about real-world objects, so our brains never evolved to be sensitive to the shape of shadows. As a result, inaccurately shaped shadows in works of art are not displeasing to our eyes. By contrast, artists are typically careful to depict shadows as having less luminance than the object casting the shadow, as people are sensitive to the brightness of objects relative to shadows.
Moreover, some artists, at least implicitly, use perceptual “tricks.” One such trick is the peak-shift principle, in which artists exaggerate certain features through the use of shape, shading, or color. The idea that exaggerated features enhance an intended response was first articulated in 1954 by the ethologist Nikolaas Tinbergen, who observed that seagull chicks more vigorously peck a disembodied long, thin stick with three red stripes at the end than they do at their mother’s beak, which has a red spot near the tip. But the use of the peak-shift principle in art predates Tinbergen. This perceptual mechanism can be seen in bronze sculptures of the 12th-century Chola dynasty in India, where the goddesses’ large breasts and hips and narrow waists enhance female sensuality, grace, poise, and dignity.
Artists also capitalize on the way the human visual system processes information in two interacting neural systems referred to as the “what” and the “where” streams. Form and color are processed in the “what” stream, revealing an object’s identity. Luminance and motion are processed in the “where” stream, which reveals an object’s location. Viewers of some impressionist paintings, such as Claude Monet’s Impression, Sunrise, observe that the effect of shimmering on water surfaces or the sun’s glow on the horizon appears because the objects are painted with the same luminance but different colors. While the brain can identify these objects, their location is hard to fix, because the “where” stream does not register objects that have the same brightness as their background. Consequently the water and the sun in the Monet painting are seen as unstable in their location, lending the painting that shimmering quality.
Viewers of some impressionist paintings, such as Claude Monet’s Impression, Sunrise, observe that the effect of shimmering on water surfaces or the sun’s glow on the horizon appears because the objects are painted with the same luminance but different colors.
Impression Sunrise | Claude Monet, 1872 | MUSEE MARMOTTAN MONET, PARIS, FRANCE/GIRAUDON/THE BRIDGEMAN ART LIBRARY
This essay was made by Anjan Chatterjee on May 1, 2014 and public in The Scientist. For the full article click here.