Illusory spreading of watercolor

Frédéric Devinck, Joseph L. Hardy, Peter B. Delahunt, Lothar Spillmann, John S Werner

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


The watercolor effect (WCE) is a phenomenon of long-range color assimilation occurring when a dark chromatic contour delineating a figure is flanked on the inside by a brighter chromatic contour; the brighter color spreads into the entire enclosed area. Here, we determined the optimal chromatic parameters and the cone signals supporting the WCE. To that end, we quantified the effect of color assimilation using hue cancellation as a function of hue, colorimetric purity, and cone modulation of inducing contours. When the inner and outer contours had chromaticities that were in opposite directions in color space, a stronger WCE was obtained as compared with other color directions. Additionally, equal colorimetric purity between the outer and inner contours was necessary to obtain a large effect compared with conditions in which the contours differed in colorimetric purity. However, there was no further increase in the magnitude of the effect when the colorimetric purity increased beyond a value corresponding to an equal vector length between the inner and outer contours. Finally, L-M-cone-modulated WCE was perceptually stronger than S-cone-modulated WCE for our conditions. This last result demonstrates that both L-M-cone and S-cone pathways are important for watercolor spreading. Our data suggest that the WCE depends critically upon the particular spatiochromatic arrangement in the display, with the relative chromatic contrast between the inducing contours being particularly important.

Original languageEnglish (US)
Article number7
Pages (from-to)625-633
Number of pages9
JournalJournal of Vision
Issue number5
StatePublished - May 4 2006


  • Color assimilation
  • Colorimetric purity
  • Cone-modulated pattern
  • Hue
  • Watercolor effect

ASJC Scopus subject areas

  • Ophthalmology


Dive into the research topics of 'Illusory spreading of watercolor'. Together they form a unique fingerprint.

Cite this