The simplicity of the original saliency map model makes it attractive both conceptually as well as for applications, but it also engenders limitations. For instance, it has been found that eye movements are typically oriented toward the centers of objects, rather than their borders, which is where bottom–up saliency peaks [28]. Such deviations can be explained, at the cost of slightly higher complexity, by directing attention to proto-objects, rather than purely spatially defined regions of the visual scene [28], [29].