title: Lightness effects in Delboeuf and Ebbinghaus size-contrast illusions.
abstract: We examined lightness effects observed in Delboeuf and Ebbinghaus size-contrast illusions. Results of four experiments are reported. Experiment 1 was conducted with Delboeuf-like stimuli and shows that the disk that appears bigger appears either lighter or darker than the disk that appears smaller, depending on the contrast polarity between disks and background. Experiment 2 shows that the direction of these lightness effects is not influenced by the luminance of the size-contrast inducers. Experiment 3 shows that a similar lightness effect is also observed in modified Ebbinghaus size-contrast displays. Experiment 4 tested the presence of the size-contrast illusion in the stimuli used in experiments 2 and 3.
authors.affiliation: Department of Psychology, University of Trieste, via S Anastasio 12, I 34134 Trieste, Italy. olga.daneyko@gmail.com
authors.forename: Olga
authors.initials: O
authors.lastname: Daneyko
authors.forename: Daniele
authors.initials: D
authors.lastname: Zavagno
authors.forename: Lucia
authors.initials: L
authors.lastname: Zanuttini
mesh_terms: D000293:Adolescent; D000328:Adult; D015350:Contrast Sensitivity; D005260:Female; D006801:Humans; D008029:Lighting; D008297:Male; D008875:Middle Aged; D009903:Optical Illusions; D012858:Size Perception; D055815:Young Adult