title: New laws of simultaneous contrast?
abstract: Drawing on many seemingly disparate and unrelated lines of evidence, we argue that the direction of the simultaneous contrast effect in three-dimensional colour space is given by the difference vector between target and surround ('direction hypothesis'). This challenges  the traditional idea according to which the direction of the simultaneous contrast effect is complementary to the colour of the surround ('complementarity law'). We also argue that the size of the simultaneous contrast effect is either constant or decreases with the difference  between target and surround in three-dimensional colour space. The latter proposal challenges Kirschmann's fourth law. Within our theoretical framework, the universally presumed validity of the complementarity law and Kirschmann's fourth law can be understood as resulting from  the failure to take various confounding factors into account when interpreting empirical data, the most prominent of which is the influence of temporal von Kries adaptation.
authors.affiliation: Institut für Psychologie, Universität Kiel, Olshausenstraße 62, 24118 Kiel, Germany. vekroll@psychologie.uni-kiel.de
authors.forename: Vebjørn
authors.initials: V
authors.lastname: Ekroll
authors.forename: Franz
authors.initials: F
authors.lastname: Faul
mesh_terms: D003118:Color Perception / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D008960:Models, Psychological; D010775:Photic Stimulation; D011601:Psychophysics