Eye fixations near corners: evidence for a centre of gravity calculation based on contrast, rather than luminance or curvature

Abstract

Subjects scanned line drawings of polygons in order to count the number of corners. The positions their eyes fixated were studied as a function of the size of the angle and whether the apex of the angle was present or absent. The results showed that the eyes tended to land at a position near the centre of gravity of the corner configurations. The observed landing positions were coherent with the hypothesis that the centre of gravity was calculated within an attentional spotlight centred on the apex of the corners, and that the calculation was based not on the total luminance distribution, nor on the distribution of energy in a neurophysiologically motivated curvature detector, but simply on the basis of a contrast detector.