An optical illusion that helps to better understand vision

The illustration is called expanding hole was created by Prof. Akiyoshi Kitaoka of Ritsumeikan University, Japan. This is a completely static image showing scattered black oval shapes on a white background in the middle of smaller shapes of the same type.

” The area and the gradient of the shadow around it give the impression of optical flow, as if the observer were heading towards a hole or a tunnel. “

The deceived student

Professor Kitaoka collaborated with Norwegian scientists from the University of Oslo to study the effects of his illustration on the vision of 50 participants aged 18 to 40 with normal vision.

First observation: 86% of the participants looking at the photo had the impression that the circle was growing and swallowing its environment.

The researchers also discovered that the illusion affects the pupil, the small black circle in the center of the eye that controls the amount of light directed at the retina. Their experiments show that students widen when the eyes are focused on the image of the black hole.

The image of the expanding hole gives the eyes the impression that it is growing and the darkness aroundnote the authors, whose work was published in the journal Limitations of Human Neuroscience (New window) (in English). This misconception leads to dilation of the pupil, when no change associated with light has actually occurred.

According to neuropsychologist Bruno Laeng, of the University of Oslo, this experiment tends to show that the pupillary reflex to light is not only mechanical and that it is unaffected by information other than the actual amount of light that stimulates the photoreceptors. The eye adapts not only to physical energy, but also to perceived light.

In their experiment, the team also varied the size and color of the area.

When the area is colored (including white), that is, it emits light, its observation diminishes the pupils, but expands. subjective is less intense than seen with black spots.

There are many optical images that suggest an idea of ​​illusory motion, even if they are completely static.

These false movements include, but are not limited to, changes in shape or space, such as rotation, oscillation, progression, flutter, contraction or, in this case, expansion.