Click on the image to see a PDF version (for zooming in)

Fig. 13.16. Contour completion process in the illusory triangle. Each element in the triangle is identified by a number 1 through to 9 counterclockwise from the top left vertex, with 2, 5, and 8 denoting the gaps. (a) A complete triangle with gaps in the middle of each side approximates the central triangular part of the edge-detected Kanizsa triangle (Figure 13.4). The MUAs corresponding to gaps are all active and synchronized with the other inputs. Overall, the synchronization of all nine inputs means that the system is perceiving a single coherent object (as also demonstrated quantitatively in Figure 13.18). (b) When one vertex (elements 6 and 7) is removed, areas representing gaps 5 and 8 become almost silent: The perception of a triangle disappears, as it does in the incomplete Kanizsa triangle (Figure 13.17). An animated demo of these examples can be seen at ...