When we do something as apparently simple as sketching a map, constructing a working diagram, or drawing an imaginary face to amuse ourselves, we utilise a complex set of abilities: perceptual, mechanical, strategic, representational, pragmatic. Peter van Sommers sets out to distinguish and describe the various layers of organisation in the drawing performances of ordinary people - adults and children. Drawings, like language, have a multi-layered structure. Because much of the structure represents tacit knowledge, a variety of special observational and analytic methods must be developed to provide a comprehensive empirical account of graphic production. This book illuminates the link between laboratory methods and the study of an important skill exercised in the real world. It will be of interest to a wide range of cognitive psychologists as well as to many neuropsychologists and others concerned with art, aesthetics, writing and script evolution.