Cornsweet Illusion

The Cornsweet illusion is a classic example of a brightness illusion, which is an illusion in which two areas that are physically the same brightness appear to be different in brightness.

The Cornsweet illusion is created by a gradual change in brightness between two areas, such as a transition from a dark area to a light area. The brain interprets the transition as a difference in brightness, even though the two areas are physically the same brightness.

Cornsweet illusion
Cornsweet illusion


Table of Contents


How does the Cornsweet Illusion work?

The Cornsweet illusion works by taking advantage of the way our visual system processes visual information. The visual system is more sensitive to changes in brightness at the borders of an object than to the brightness of the object itself.

In the Cornsweet illusion, there is a gradual change in brightness between two areas, such as a transition from a dark area to a light area. The brain interprets the transition as a difference in brightness, even though the two areas are physically the same brightness.

The way it works is that the visual system is sensitive to edges and it tends to exaggerate the brightness difference at the border between two adjacent regions. The brain tends to perceive the brightness of one area based on the brightness of the adjacent area, which causes the illusion of a difference in brightness.

Additionally, the visual system is sensitive to the relative brightness of an area, rather than its absolute brightness. The brain compares the relative brightness of an area to the surrounding areas, this causes the brain to perceive the brighter area as less bright and the darker area as brighter, than they actually are.

The Cornsweet illusion is important in the field of visual perception and cognitive psychology because it provides insight into how the brain processes visual information and how it interprets brightness. It also plays a role in areas such as computer graphics and image processing, where it is used to create the illusion.

Versions of the Cornsweet Illusion

The following are an alternate versions of the Cornsweet Illusion:



Cornsweet illusion
Both Sides are the Same Color


Cornsweet illusion
Both Sides are the Same Color


Cornsweet illusion
Both Sides are the Same Color






Illusions like the Cornsweet Illusion

The Cornsweet illusion is a type of visual illusion known as a brightness illusion. A brightness illusion is an illusion in which two areas that are physically the same brightness appear to be different in brightness.

Brightness illusions are important in the field of visual perception and cognitive psychology because they provide insight into how the brain processes visual information and how it interprets brightness. They also play a role in areas such as computer graphics and image processing, where they are used to create the illusion of depth and texture.

Some related illusions include the following:

The Checker Shadow Illusion is created by a checkerboard pattern composed of squares with different luminance values, the squares that are not directly illuminated by the light source appear darker than the illuminated squares, creating the illusion of shadows.

Edelson-Checker_shadow_illusion
Checker Shadow Illusion

The simultaneous contrast illusion is a visual effect that occurs when the perception of a color is affected by the colors of the surrounding area.

The illusion creates the appearance of a change in the color of an object, even though the actual color of the object remains constant.

Simultaneous Contrast Effect
The center green dot is the same on both sides, but the surrounding color changes the perception

The Neon Color Spreading illusion refers to the visual phenomenon where an area of color appears to spread or “bleed” beyond its intended boundaries.

Neon Color Spreading
From Wikimedia Commons

The Bezold Effect: This illusion is created by placing two or more colors next to each other, and the way they appear to change when they are close to one another.  

Bezold_Effect
from Wikimedia Commons

The Mach Band Illusion: This illusion is created by the way the brain perceives edges of an object. When an object has a gradient of color, the edges of the object appear to be darker or lighter than they actually are.

Mach Bands Animation
From Wikimedia Commons

The Chubb illusion is based on the perception of brightness and can be observed when a small bright patch is surrounded by a larger dark area, the small bright patch will appear brighter than the same patch surrounded by a bright area.

Chubb Illusion


The Chevreul Illusion: This illusion is created by the way the brain perceives edges of an object. When the edges of an object are surrounded by a contrasting color, the edges appear to be a different color than they actually are. Chevreul’s illusion is similar to Mach bands, but they work in different ways. Chevreul’s illusion is an effect on the perception of hue, while Mach bands is an effect on the perception of brightness.

chevreul

White’s illusion is a visual phenomenon in which two identical gray bars are placed on a background of alternating black and white stripes.

The gray bars appear to be different shades of gray, with the one on the white stripes appearing lighter than the one on the black stripes.

In the image below, both gray bars have the exact same color.

White's Illusion
White’s Illusion

The Watercolor Illusion: This illusion is created by the way the brain perceives edges of an object. When an object is surrounded by a colored halo, the object appears to have a different color than it actually does.

Watercolor Illusion


The Café Wall Illusion is a visual illusion that is created by a grid of alternating light and dark horizontal and vertical lines. The lines appear to be bent or tilted, even though they are actually straight.

Cafe Wall Illusion


Discovery of the Cornsweet Illusion

The Cornsweet illusion is a visual illusion that was first described by Tom Cornsweet in 1960.

Tom Cornsweet was an American psychologist, known for his work in visual perception. He was a Professor of Psychology at the University of California, Berkeley, and a Fellow of the American Psychological Association. He is best known for his research on the physiology of visual perception and for his descriptions of visual phenomena such as the Cornsweet illusion.

Cornsweet published several papers on various topics related to visual perception, including the perception of brightness, color, and contrast. He is known for his work in the field of visual perception and cognitive psychology, he also worked on the perception of brightness and color, and on the perception of visual illusions.

He was a pioneering researcher in the field of visual perception, and his work continues to be influential in the field today. The Cornsweet illusion, which is named after him, is still widely used in the study of visual perception and cognitive psychology, as well as in areas such as computer graphics and image processing.

Cornsweet passed away in the late 90s, but his contributions to the field of visual perception and cognitive psychology are still widely recognized and respected today.

References and Resources

Check out our complete list of illusions.

Sign Up to Have Your Mind Blown