Lightness constancy: ratio invariance and luminance profile

SORANZO, Alessandro, GALMONDE, Alessandro and AGOSTINI, Tiziano (2009). Lightness constancy: ratio invariance and luminance profile. Attention, Perception, & Psychophysics, 71 (3), 463-470.

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    Link to published version:: 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.

    Item Type: Article
    Additional Information: The final publication is available at
    Research Institute, Centre or Group: Psychology Research Group
    Identification Number: 10.3758/APP.71.3.463
    Related URLs:
    Depositing User: Alessandro Soranzo
    Date Deposited: 25 Sep 2012 11:39
    Last Modified: 25 Sep 2012 12:39

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