Home LATEST NEWS An optical illusion that helps to better understand vision

An optical illusion that helps to better understand vision


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

The spot and the gradient of shadow around it evoke an impression of optical flow, as if the observer were heading towards a hole or a tunnel. »

A quote from Akiyoshi Kitaoka

The deceived pupil

Professor Kitaoka teamed up 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 sight.

Photo: Wikipedia/Greyson Orlando

First observation: 86% of the participants who look at the image have the impression that the circle grows and engulfs its environment.

The researchers also discovered that the illusion affects the pupil, the small black circle in the middle of the eye that regulates the amount of light directed to the retina. Their experiments show that the pupils dilate when the eyes focus on the image of the black hole.

The image of the expanding hole gives the eyes the impression that it is getting bigger and the darkness is increasing aroundnote the authors, whose work is published in the journal Frontiers in Human Neuroscience (New window) (in English). This false perception leads to the dilation of the pupil, when no light-related change 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 not impervious to information other than the actual amount of light stimulating the photoreceptors. The eye would adapt not only to physical energy, but also to perceived light.

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

When the spot is colored (including white), that is, it emits light, its observation narrows the pupils, but the expansion subjective is also less intense than that perceived with a black spot.

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

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

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