Dynamical constraints on pictorial action lines.

Pictorial action lines are an effective way of portraying movement in a static drawing. When such lines emanate from the backs of characters, they can give a sense of the path or style of movement. Seven experiments assessed whether photographic streak lines-lines that depict actual movement paths-can, in and of themselves, be informative about the act that produced them. Lines were produced as a darkly clad actor with point-lights attached to his major joints performed a number of actions in front of an open-lens camera. Completely naive Ss had little success identifying events in these photographs. Once Ss were told of the photographic technique, however, striking proficiency was achieved. Subtle distinctions (e.g., whether the movement was forward or backward or performed while wearing weights) were made for some of the events. Results are discussed in terms of various treatments of pictorial information.