Depth inversion with a 3D structure influences brightness perception.

Tetsuya Arai,Keiko Omori,Yasunori Aizawa,Yuka Igarashi,Tomohiro Masuda,Naoe Masuda,J Malo

doi:10.1371/journal.pone.0224192

Abstract

Whether or not depth perception influences brightness and/or lightness perception has been repeatedly discussed, and some studies have emphasized its importance. In addition, a small number of studies have empirically tested and shown the effect of depth inversion, such as seen in the Mach card illusion, on perceived lightness, and they interpreted such results in terms of lightness constancy. However, how perceived brightness changes contingent on depth inversion remains unexplained. Therefore, this study used the matching method to examine changes in brightness perception when depth inversion is observed. We created and used a three-dimensional (3D) concave object, composed of three sides made of card stock, which could be perceived as having two different shapes in 3D; it could be perceived as a horizontal concave object, corresponding to its actual physical structure, and as a convex standing object, similar in shape to a building. Participants observed this object as both a concave object and as a convex object, and judged the brightness of its surfaces during each observation. Our results show that the perception of the brightness of the object’s surfaces clearly changed depending on the perception of depth. When the object was seen as convex, one part of the surface was perceived as darker than when the object was seen as concave, but the other part of the surface remained unchanged. Here we discuss the relationship between depth perception and brightness perception in terms of perceptual organization.

Highlights

While there are various definitions of brightness and lightness [1], brightness is often defined as a perceptional dimension corresponding to luminance that varies from dark to bright
In Gilchrist’s experiments, the perceived surface changed from nearly white to nearly black only as a function of its perceived spatial position with no critical change in retinal image. These findings led to a coplanar ratio principle, according to which, luminance ratios between regions within the same depth plane are more significant in perceived lightness than ratios between regions within different depth planes
Effects of perceived depth on brightness or lightness were replicated with more sophisticated measurements, so that it is believed that perceived arrangement can influence brightness and lightness perception

Summary

Introduction

While there are various definitions of brightness and lightness [1], brightness is often defined as a perceptional dimension corresponding to luminance that varies from dark to bright. In Gilchrist’s experiments, the perceived surface changed from nearly white to nearly black only as a function of its perceived spatial position with no critical change in retinal image These findings led to a coplanar ratio principle, according to which, luminance ratios between regions within the same depth plane are more significant in perceived lightness than ratios between regions within different depth planes. Radonjić, Todorović & Gilchrist [7] developed Gilchrist’s theory and the Kardos study [6], and observed a large depth effect on lightness without adjacency In this way, effects of perceived depth on brightness or lightness (depth effects) were replicated with more sophisticated measurements, so that it is believed that perceived arrangement can influence brightness and lightness perception

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