The Ebbinghaus illusion (also known as Titchener circles) is a perceptual illusion in which the perceived size of a central circle is affected by the size of the surrounding circles. The central circle appears smaller when surrounded by larger circles, and larger when surrounded by smaller circles.
Table of Contents
- How does the Ebbinghaus Illusion work?
- Versions of the Ebbinghaus Illusion
- Illusions like the Ebbinghaus Illusion
- Discovery of the Ebbinghaus Illusion
- References and Resources
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How does the Ebbinghaus Illusion work?
The Ebbinghaus illusion works by exploiting the way our brain processes visual information. Our brain is constantly trying to make sense of the visual information it receives by making comparisons and judgments about the size, shape, and position of objects in our environment. In the case of the Ebbinghaus illusion, the brain is making a comparison between the size of the central circle and the size of the surrounding circles.
When the surrounding circles are larger than the central circle, our brain perceives them as being farther away and thus the central circle appears smaller in comparison. When the surrounding circles are smaller than the central circle, our brain perceives them as being closer and the central circle appears larger in comparison.
Additionally, the brain also takes into account the proximity of the surrounding circles to the central circle. So, if the surrounding circles are placed in close proximity to the central circle, it will appear smaller than when they are placed farther away.
This illusion is thought to be caused by a neural mechanism in the brain called contextual modulation, which modifies the visual perception of an object based on the context in which it is presented. The Ebbinghaus illusion is a classic example of how context can affect perception and highlights the complex nature of visual processing in the brain.
Versions of the Ebbinghaus Illusion
The following are some alternate versions of the Ebbinghaus Illusion
Illusions like the Ebbinghaus Illusion
The Ebbinghaus illusion is a type of size-contrast illusion. A size-contrast illusion is a type of visual illusion in which the perceived size of an object is affected by the size of the surrounding objects. The Ebbinghaus illusion specifically is related to relative size, where the perception of the size of the central circle changes depending on the size of the surrounding circles. Size-contrast illusions occur due to the way that the visual system processes relative size information in a scene, and the Ebbinghaus illusion is a classic example of this type of illusion.
There are many other examples of size-contrast illusions in addition to the Ebbinghaus illusion. Here are a few examples:
The Delboeuf illusion is similar to the Ebbinghaus illusion, but instead of circles, it uses two concentric circles or rings. The central ring appears larger or smaller depending on the size of the surrounding ring.
The Poggendorff illusion is another size-contrast illusion in which a straight line appears to be bent or angled, due to the presence of intersecting lines or shapes in the background.
The Zöllner illusion is another size-contrast illusion in which a group of diagonal lines appear to be distorted or bent due to the presence of intersecting lines.
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.
All of these illusions rely on the way the visual system processes relative size information, and they all highlight the complexity and malleability of visual perception.
Discovery of the Ebbinghaus Illusion
This illusion is named after German psychologist Hermann Ebbinghaus, who first described it in the late 19th century. The illusion is thought to be caused by the way the brain processes relative size information in visual scenes.
Hermann Ebbinghaus (1850-1909) was a German psychologist who is best known for his pioneering research on memory and forgetting. He was one of the first researchers to systematically study memory as a psychological process and his work laid the foundation for the field of experimental psychology. Ebbinghaus conducted a series of experiments in which he memorized lists of nonsense syllables and then tested his own memory at various intervals to measure the rate of forgetting.
He also developed the first standardized memory test, called the “memory drum”, which consisted of a rotating drum with lists of words or syllables that could be presented to participants at different intervals. He used these tests to study the effects of different factors, such as repetition and interference, on memory retention.
Ebbinghaus also made significant contributions to the understanding of memory processes, such as the spacing effect, which states that spaced practice is more effective than massed practice in enhancing memory retention.
Ebbinghaus’s work was groundbreaking in the field of psychology and is still widely cited today. The Ebbinghaus illusion, the size-contrast illusion that bears his name, was discovered by him in 1885 but is not as well-known as his memory research.
References and Resources
Check out our complete list of illusions.
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