A Caltech Library Service

The Brain Knows enough to take into account Light and Shadow

Yamamoto, Masahiro and Shimojo, Shinsuke (2020) The Brain Knows enough to take into account Light and Shadow. . (Unpublished)

[img] PDF - Submitted Version
Creative Commons Attribution Non-commercial No Derivatives.

[img] PDF - Supplemental Material
Creative Commons Attribution Non-commercial No Derivatives.


Use this Persistent URL to link to this item:


Visual perception requires to infer object and light source color to maintain constancy. This study demonstrates the influences of environmental sunlight color trajectory (blue-white-yellow-red), and associated color of scattered light in shadows on color perception. In Adelson′s checkerboard shadow illusion, squares of equal luminance appear lighter or darker depending on whether they are inside or outside a cast shadow. In some color variations, illusion magnitude is attenuated by specific colors of the cast shadow. Particularly in the green monotone environment (green checkerboard under green ambient and diffusion light), illusion magnitude reduces down nearly to zero. In contrast, shading by structure is not affected by the color environment. Thus, the cast shadow and shading by structure have distinct effects on surface color constancy. This illusion attenuation may be related to the absence of green in the natural environmental light spectrum, including in cast shadows. The brain may utilize the implicit learned trajectory of natural light to resolve ambiguity in surface reflectance. Our results provide a new formula not only to understand, but also to generate new variations of other illusions such as #The Dress.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Yamamoto, Masahiro0000-0001-6196-9497
Shimojo, Shinsuke0000-0002-1290-5232
Additional Information:The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. Posted October 19, 2020. We thank our colleagues from TOSHIBA R&D center who provided insight and expertise that greatly assisted the research, although they may not agree with all of the interpretations/conclusions of this paper.
Record Number:CaltechAUTHORS:20201021-074203448
Persistent URL:
Official Citation:The Brain Knows enough to take into account Light and Shadow. Masahiro Yamamoto, Shinsuke Shimojo. bioRxiv 2020.10.19.344838; doi:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106177
Deposited By: Tony Diaz
Deposited On:21 Oct 2020 16:49
Last Modified:16 Nov 2021 18:51

Repository Staff Only: item control page