ABSTRACT
The laws which predict how the perceptual quality of figure-ground can be extracted from the most elementary visual signals were discovered by the Gestaltists, and form an essential part of their movement (see especially Metzger, 1930, and Wertheimer, 1923 translated and re-edited by Lothar Spillmann, 2009 and 2012, respectively). Distinguishing figure from ground is a prerequisite for perception of both form and space (the relative positions, trajectories, and distances of objects in the visual field). The human brain has an astonishing capacity for selecting and combining a few critical visual signals, through complex mechanisms, to represent form and space accurately. The phenomenon of figure-ground in its most elementary form may be seen in the famous Ehrenstein illusion (Ehrenstein, 1941, studied extensively by Spillmann and colleagues, see Dresp-Langley, 2009, for a general review). In this illusion, four thin lines form a cross configuration with an empty centre (as in Figure 12.1). Examples of the Ehrenstein illusion, which was extensively studied by Spillmann and his colleagues. A shape percept is induced by dark or bright converging lines, where a disk lying in front of the display is perceived. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203076323/a746b50f-9ff7-4629-8090-464ce5fdc2de/content/fig12_01_C.jpg" xmlns:xlink="https://www.w3.org/1999/xlink"/>
