EFFECTS OF CONTOUR-LINE THICKNESS OF THE TEST FIGURE ON HUE CONTRAST IN KOFFKA-RING TYPE PATTERNS

The purpose of this study is to investigate the effects of contour-lin e thickness of a test figure (TF) on hue contrast in Koffka-ring type patterns from the viewpoint that the contour-line thickness affects th e perception of the TF's unity. Six subjects were instructed to adjust a comparison figure (CF) to match the apparent hue of the two TF sect ions overlapping a red-green inducing figure (IF) with a gray backgrou nd. By using a color-graphic system, the following stimulus conditions were manipulated; 1) the contour-line thickness of the TF (four degre es), 2) the separation of the TF (three degrees), and 3) the employmen t of control stimuli in which the IF was either completely red or gree n in order to check the contour-line thickness as a distance between t he TF and the IF. The results revealed that the magnitudes of hue cont rast (MHCs) decreased as the contour-line thickness increased. In addi tion, a questionnaire to rate the unity of the TF supported the view t hat a contour-line thickness intensifies the perceived unity of the TF . Consequently, it is concluded that the contour-line thickness affect s the increase of the TF's unity and that the MHCs of the TF surrounde d by thick contour-line decrease.