EYE FIXATIONS NEAR CORNERS - EVIDENCE FOR A CENTER OF GRAVITY CALCULATION BASED ON CONTRAST, RATHER THAN LUMINANCE OR CURVATURE

Subjects scanned line drawings of polygons in order to count the numbe r of corners. The positions their eyes fixated were studied as a funct ion of the size of the angle and whether the apex of the angle was pre sent or absent. The results showed that the eyes tended to land at a p osition near the centre of gravity of the corner configurations. The o bserved landing positions were coherent with the hypothesis that the c entre of gravity was calculated within an attentional spotlight centre d on the apex of the corners, and that the calculation was based not o n 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.