明るさの恒常性に関する一考察
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概要
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As one of characteristics of objects their blackness or whitness tend to remain invariant despite changing illumination. Such a phenomenon is called lightness constancy. In the present paper several theories which might be applicable to the problems of lightness constancy were briefly reviewed. First, it was argued whether this phenomenon could be adequately explained by Wallach's ratio theory (1948) which suggestes that the apparents lightness of a achromatic surface remains unchanged irrespetive of the illumination if its ratio to the surrounding in luminance is kept constant. The ratio principle, however, failed in its application to the conditions in which there were more than three different luminous intensities simultaneously illuminating a ratina. One needs more adequate theory which can be applied not only to simple experimental conditions but also to the natural environment in which there are complex gradients of luminous intensities. In the second place, the problems of lightness constancy was discussed from the view-point of adaptation-level theory (AL theory) provided by Helson (1938) which states, in essence, that the zero of organic functions shifts with changing conditions, there by preserving invariant relations between the stimuli and the organism. It was emphasized that in AL thory the pooling effects of all luminous intensities in the visual field are taken into account and thus the possibilities of explaining this phenomenon in terms of AL theory will be found.
- 東京女子大学の論文
- 1970-03-31