Delboeuf Illusion

The Delboeuf illusion is a perceptual illusion in which the perceived size of a circle is affected by the size of the surrounding circles.

In the illusion, a central circle surrounded by larger circles appears smaller than the same central circle surrounded by smaller circles, even though the central circle is identical in both cases. The illusion demonstrates that the perceived size of an object can be influenced by the context in which it is presented.

Delboeuf illusion Large
The Delboeuf Illusion

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How does the Delboeuf Illusion work?

The Delboeuf illusion works by altering the perceived relative size of the central circle compared to the surrounding circles. The brain uses the size of the surrounding circles as a reference point to judge the size of the central circle. When the surrounding circles are larger, the central circle appears smaller in comparison, and when the surrounding circles are smaller, the central circle appears larger.

This illusion is thought to be caused by a process in the brain called “size constancy scaling.” This process allows the brain to adjust for the size of an object relative to its surroundings. In the Delboeuf illusion, the brain incorrectly adjusts the perceived size of the central circle based on the size of the surrounding circles.

It’s also thought that the Delboeuf illusion is caused by the way the brain processes the spatial relationships between objects. The brain uses distance and angle as cues to determine the size of an object, and these cues can be influenced by the presence of surrounding objects. In the case of the Delboeuf illusion, the brain may interpret the larger surrounding circles as being closer to the central circle, making the central circle appear smaller.

It’s important to note that the Delboeuf illusion is not limited to circles, it works also with other shapes and sizes, it’s a general principle that applies to all types of stimuli.

Versions of the Delboeuf Illusion

The following are some versions of the Delbouf Illusion

Delboeuf circle with lines
Delboeuf Illusion Circles
Delboeuf Illusion Food Pasta
Delboeuf Illusion Circle Square

Illusions like the Delboeuf Illusion

The Delboeuf Illusion is a size constancy illusions in which the perceived size of an object is affected by its surroundings. Some examples of size constancy illusions include:

The Ebbinghaus illusion: This illusion is similar to the Delboeuf illusion but in this case the central circle appears larger when surrounded by smaller circles and smaller when surrounded by larger circles.

Ebbinghaus Illusion

The Occlusion illusion is a visual illusion where an object that is partially obscured by another object appears to be farther away than it actually is. This illusion is caused by the brain’s interpretation of the relative depth of the objects based on their relative size and position. This phenomenon is based on the visual cues that the brain uses to perceive depth, such as relative size, position, and overlap.

The occlusion illusion

The Müller-Lyer illusion is a classic example of size-contrast illusion, in which two lines of equal length appear to be different due to the presence of arrowheads or fins at the end of the lines.

müller-lyer illusion

Moon illusion: This illusion involves the perception of the Moon appearing larger when it is near the horizon compared to when it is high in the sky.

Moon Illusion

Ponzo illusion: This illusion involves the perception of an object appearing larger or smaller depending on the size of the surrounding context.

Ponzo Illusion

All these illusions demonstrate that the perceived size of an object can be influenced by the context in which it is presented, and that the brain uses the size of the surrounding objects as a reference point to judge the size of the central object.

Discovery of the Delboeuf Illusion

The illusion is named after the Belgian psychologist Joseph Delboeuf, who first described it in 1865.

Joseph Remi Leopold Delboeuf (1831-1896) was a Belgian psychologist and philosopher who is best known for his work on the Delboeuf illusion, a perceptual illusion in which the perceived size of a circle is affected by the size of the surrounding circles. Delboeuf was one of the early pioneers of experimental psychology, and his work on the Delboeuf illusion was an important contribution to our understanding of how the brain processes visual information.

Delboeuf was born in Brussels, Belgium in 1831. He studied mathematics, physics and chemistry at the University of Brussels and later received a degree in medicine. He then studied philosophy and psychology at the Universities of Leipzig and Berlin. After completing his education, he returned to Brussels and became a professor of psychology at the University of Brussels. He also founded the Belgian Society for Psychology.

Delboeuf’s work on the Delboeuf illusion was published in 1865, in which he presented the illusion and demonstrated that the perceived size of an object can be influenced by the context in which it is presented. His work in this area was important in showing that visual perception is not just a passive process, but that the brain actively interprets the information it receives. He also made other contributions to the field of psychology, he studied the perception of time, and he wrote on the philosophy of psychology.

Delboeuf died in 1896 in Brussels, Belgium. His legacy in psychology is still being studied and cited today.

Impact of the Delboeuf Illusion in the Food Industry

The Delboeuf illusion impacts the food industry in a few ways.

First, the illusion can be used to make food portions appear larger or smaller than they actually are. For example, using smaller plates or bowls can make a small portion of food appear larger, while using larger plates or bowls can make a large portion of food appear smaller. This can be used to create the illusion of value for customers, or to make healthier portion sizes appear more satisfying.

Second, the Delboeuf illusion can be used in food packaging design. For example, using larger or smaller images of food on packaging can make the contents of the package appear larger or smaller than they actually are. This can be used to make smaller products appear more appealing or to make larger products appear more economical.

Third, the Delboeuf illusion can be used in restaurant settings. For example, using smaller plates or glasses can make small servings of food or drink appear larger, while using larger plates or glasses can make larger servings appear smaller. This can be used to influence customer perceptions of value and satisfaction.

It’s important to note that in the food industry, manipulating the Delboeuf illusion can be considered as a form of deceptive marketing, and in some countries, it is regulated by law. It’s important to be transparent and honest with the customers and to follow the laws.

References and Resources

Check out our complete list of illusions.

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