Visually guided drawing in the chimpanzee (Pan troglodytes)
Iver H Iversen, Tetsuro Matsuzawa
Two captive, female chimpanzees (Pan troglodytes) were taught to draw straight lines with a method of electronic finger painting. Subjects faced a touch-sensitive monitor. Because a touch instantaneously generated electronic ink in the form of a graphic symbol at the touched location, movement of the finger over the monitor surface produced a visible trace. Drawing was taught in several steps, beginning with pressing separate small circles one at a time. As the circles were moved closer and overlapped, the subjects began to connect them without lifting the finger. After smooth drawing was established, two small dots, 12 cm apart, appeared on the monitor in different orientations. Each subject drew a line connecting the dots by placing a finger on one dot and moving the finger, without lifting, to the next dot. Thereby the dot orientations guided the drawing. The subjects were not drawing by tracking a moving object but were truly free drawing. The fully automated training and recording methods generated highly accurate drawing behavior that could be measured quantitatively. Our results provide clear evidence that with training the chimpanzee is capable of structured drawing guided by visual commands.