Dimension-up mechanism of brain from 2D retinal image to 3D space recognition

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 12650045
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Applied optics/Quantum optical engineering
• Research Institution: Ritsumeikan University
• Principal Investigator: IKEDA Mitsuo Ritsumeikan Univ., Fac. Science and Engineering, Professor, 理工学部, 教授 (30016604)
• Co-Investigator(Kenkyū-buntansha): SHINODA Hiroyuki Ritsumeikan Univ., Fac. Science and Engineering, Associate Professor, 理工学部, 助教授 (40278495)
• Project Period (FY): 2000 – 2001
• Keywords: space recognition / SD picture / 3D space / demension-up / llight source color / lightness / brain function

Research Abstract

Human being lives in a three dimensional space and it is one of the most important job for the brain to recognize the 3D outsideworld in spite of the fact that its retinal image is a mere 2D picture. It is considered then that the brain automatically increase the 2D image to 3D space recognition. This hypothesis was proved by three different experiments.
A picture was taken to include a mountain at a far distance and its copies were made in which the size of the mountain was variously changed. These pictures were presented to subjects in two ways and asked them to choose one that appears most realistic. In one way the pictures were just shown placed in front of the subjects, and in the other way one picture was presented to the subjects with a so-called dimension-up goggle with which only the picture was seeable by the subjects. In the first way the subjects selected a picture in which the mountain was drawn about two to three time larger the the real size to confirm the size constancy. In the second way the subjects select the original picture, which implies that the picture was recognized as a 3D space and the size constancy took place for the space.
In the second experiment a night soene picture was presented to subjects with and without the D-up goggle. At one small place which was a window of a building various gray scale was presented and the subjects were asked to set the gray scale at the point they saw the light source color there. Without the goggle the Munsell Value of the gray scale was set at a high value, but with the goggle the Value was set at a lower vale, about two lower. This implies that the subjects could recognize a 3D space on the picture and constructed the Recognized Visual Space of Illumination of a small size of brightness. Because of the small brightness size of the RVSI the subjects could see the light source color at a low Munsell Value.
In the third experiment picture of the Necker cube was used as the stimulus. Three black gratings were drawn on the cube and two gay patches, one placed on the black gratings and the other behind the cube. When the brightness was measured for the two gray patches, the patch placed on the black gratings appeared brighter when the cube was observed through the D-up goggle. This implies that the cube was recognized as a 3D cube. When the black gratings were removed there was no difference in brightness among the two gray patches. It should imply that no 3D space was recognized and the same gray patches appeared same in brightness.
All the above experiments show that that the brain automatically increases the dimension of the retinal image to 3D if the 2D picture was only presented to the subjects by eliminating all other information than the picture.