Attention, Perception, & Psychophysics

, Volume 71, Issue 3, pp 463–470

Lightness constancy: Ratio invariance and luminance profile

  • Alessandro Soranzo
  • Alessandra Galmonte
  • Tiziano Agostini
Research Articles

DOI: 10.3758/APP.71.3.463

Cite this article as:
Soranzo, A., Galmonte, A. & Agostini, T. Attention, Perception, & Psychophysics (2009) 71: 463. doi:10.3758/APP.71.3.463


The term simultaneous lightness constancy describes the capacity of the visual system to perceive equal reflecting surfaces as having the same lightness despite lying in different illumination fields. In some cases, however, a lightness constancy failure occurs; that is, equal reflecting surfaces appear different in lightness when differently illuminated. An open question is whether the luminance profile of the illumination edges affects simultaneous lightness constancy even when the ratio invariance property of the illumination edges is preserved. To explore this issue, we ran two experiments by using bipartite illumination displays. Both the luminance profile of an illumination edge and the luminance ratio amplitude between the illumination fields were manipulated. Results revealed that the simultaneous lightness constancy increases when the luminance profile of the illumination edge is gradual (rather than sharp) and homogeneous (rather than inhomogeneous), whereas it decreases when the luminance ratio between the illumination fields is enlarged. The results are interpreted according to the layer decomposition schema, stating that the visual system splits the luminance into perceived lightness and apparent illumination components. We suggest that illumination edges having gradual and homogeneous luminance profiles facilitate the luminance decomposition process, whereas wide luminance ratios impede it.

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Copyright information

© Psychonomic Society, Inc. 2009

Authors and Affiliations

  • Alessandro Soranzo
    • 1
  • Alessandra Galmonte
    • 2
  • Tiziano Agostini
    • 3
  1. 1.School of Social Science and LawUniversity of TeessideMiddlesbroughEngland
  2. 2.University of VeronaVeronaItaly
  3. 3.University of TriesteTriesteItaly