SORANZO, Alessandro, GALMONTE, Alessandro and AGOSTINI, Tiziano (2010). Von Bezold assimilation effect reverses in stereoscopic conditions. Perception, 39 (5), 592-605.
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Lightness contrast and lightness assimilation are opposite phenomena: in contrast, grey targets appear darker when bordering bright surfaces (inducers) rather than dark ones; in assimilation, the opposite occurs. The question is: which visual process favours the occurrence of one phenomenon over the other? Researchers provided three answers to this question. The first asserts that both phenomena are caused by peripheral processes; the second attributes their occurrence to central processes; and the third claims that contrast involves central processes, whilst assimilation involves peripheral ones. To test these hypotheses, an experiment on an IT system equipped with goggles for stereo vision was run. Observers were asked to evaluate the lightness of a grey target, and two variables were systematically manipulated: (i) the apparent distance of the inducers; and (ii) brightness of the inducers. The retinal stimulation was kept constant throughout, so that the peripheral processes remained the same. The results show that the lightness of the target depends on both variables. As the retinal stimulation was kept constant, we conclude that central mechanisms are involved in both lightness contrast and lightness assimilation.
|Additional Information:||Alessandro Soranzo, 2010. The definitive, peer-reviewed and edited version of this article is published in Perception, 39, 5, 592-605, doi: 10.1068/p6462|
|Research Institute, Centre or Group:||Psychology Research Group|
|Depositing User:||Alessandro Soranzo|
|Date Deposited:||25 Sep 2012 12:13|
|Last Modified:||25 Sep 2012 12:39|
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