Definition:

The Delboeuf illusion is a visual phenomenon that occurs when the size of a surrounding context influences our perception of the size of an object placed within it.

Subtitles:

  1. Overview

    2. The Delboeuf illusion is an optical illusion discovered by the Belgian psychologist Joseph Delboeuf in 1865. It demonstrates how the presence of a surrounding ring or frame can alter our perception of the size of an object at the center of the ring.

  2. The Illusion

    3. In the Delboeuf illusion, two identical central circles are presented, one surrounded by a larger concentric circle and another by a smaller one. Despite the fact that the central circles are the same size, the one surrounded by the larger context appears smaller, while the one surrounded by the smaller context appears larger. This creates a perceptual distortion of the central object’s size based on the influence of the surrounding context.

  3. Factors Affecting Perception

    4. Multiple factors contribute to the Delboeuf illusion, including the size of the surrounding context and the relative sizes of the central and surrounding circles. The illusion is most pronounced when the surrounding context is significantly larger or smaller than the central object, creating a stark contrast in size.

  4. Possible Explanations

    5. Psychologists propose various explanations for the Delboeuf illusion. One theory suggests that our brain uses the surrounding context as a reference point to judge the size of the central object. Another theory posits that the illusion occurs due to misperception of the size-distance relationship between the central and surrounding circles.

  5. Real-World Examples

    6. The Delboeuf illusion can be observed in various real-world situations, such as plate size influences on food consumption. A larger plate can make a portion of food appear smaller, leading to potential overeating. This illusion has implications in areas ranging from visual art and design to marketing and portion control.