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100			_aKobayashi, Yuki _949297
245			_aAn Upward-Facing Surface Appears Darker: The Role Played by the Light-From-Above Assumption in Lightness Perception/
260			_bsage _c2019
300			_aVol 48, Issue 6, 2019: (500-514 p.).
520			_aThe human visual system can extract information on surface reflectance (lightness) from light intensity; this, however, confounds information on reflectance and illumination. We hypothesized that the visual system, to solve this lightness problem, utilizes the internally held prior assumption that illumination falls from above. Experiment 1 showed that an upward-facing surface is perceived to be darker than a downward-facing surface, proving our hypothesis. Experiment 2 showed the same results in the absence of explicit illumination cues. The effect of the light-from-left prior assumption was not observed in Experiment 3. The upward- and downward-facing surface stimuli in Experiments 1 and 2 showed no difference in a two-dimensional configuration or three-dimensional structure, and the participants’ perceived lightness appeared to be affected by the observers’ prior assumption that illumination is always from above. Other studies have not accounted for this illusory effect, and this study’s finding provides additional insights into the study of lightness perception.
650			_alightness/brightness, _949298
650			_alight-from-above assumption, _949299
650			_atop-down processing, _949300
650			_asurface orientation, _949301
650			_a illumination _949302
700			_aMorikawa, Kazunori _949303
773	0		_012374 _916462 _dSage, _tPerception _x1468-4233
856			_uhttps://doi.org/10.1177/0301006619847590
942			_2ddc _cART
999			_c12436 _d12436