Authors: Masataka Suzuki, Masayo Noda, Kazufumi Takahashi

Country: Japan

Description: Our video contains three still images. The first image shows 16 transparent discs randomly arranged on a black background so that they partially overlap each other. If you look at the whole image with keeping fixation on a central cross, you will immediately notice that one disc appears to be nearer and brighter than the others. This scheme will be succeeded in one of the other discs even in the absence of eye movements, as if a new bubble appears one after another on the surface of water. The second image shows the contours of all the circles in the first image, drawn with only the solid lines. Surprisingly, the dynamic changes in the depth order among circles, which are similar to that experienced in the transparent situation, can be confirmed. However, when the depth order of overlapping circles is uniquely determined, as shown in the third image, perceptual alternation never occurs. When faced with ambiguous images, like those in the first two images, our brain appears to work diligently to find a unique solution.