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Fig. 13.18. Contour completion performance in the illusory triangle. Each side of the triangle is represented by a group of three MUA sequences, and constitutes a separate contour. The average correlation coefficients were calculated over two trials for MUA sequences representing two elements within the same side, across different sides, anywhere in the whole triangle, one in a contour and the other in the background, and within the background. The elements in each side are strongly synchronized, but so are elements across different sides and in the whole triangle (the differences between "Within", "Across", and "Whole" are not significant with p > 0.1). Furthermore, the elements in the triangle are significantly more synchronized than contour and background elements, and elements in the background (p < 10^-6). This result shows quantitatively that the three sides are perceived together as a single object.