Expanding Flower Illusion

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This Expanding Flower Illusion is a version of the “Expanding/Contracting Motion Illusion” or the “Troxler Effect.” In this illusion, when you fixate your gaze on a particular point, shapes located in your peripheral vision appear to expand or contract over time, even though they are actually static.

Expanding Flower Illusion


Table of Contents

What is the Expanding Flower Illusion?

The Expanding Flower Illusion is commonly known as the “Expanding/Contracting Motion Illusion” or the “Troxler Effect.” In this illusion, when you fixate your gaze on a particular point, shapes located in your peripheral vision appear to expand or contract over time, even though they are actually static.

Here’s how the Expanding Flower Illusion works:

  1. Fixation Point: The illusion begins with a central fixation point that you focus on directly. This helps to stabilize your central gaze while the peripheral vision is engaged.
  2. Peripheral Shapes: Surrounding the fixation point are shapes or objects, usually simple patterns such as circles, squares, or lines. These shapes are carefully designed to create the illusory effect.
  3. Perception of Expansion/Contraction: As you maintain fixation on the central point, the peripheral shapes may appear to expand or contract, as if they are growing or shrinking in size. The illusory motion is perceived in the peripheral vision, and the effect can be more pronounced when the shapes have high contrast or sharp edges.

The Expanding Flower Illusion is thought to occur due to a phenomenon known as “peripheral drift,” where the peripheral visual information is not as precisely processed as the central vision. As a result, the peripheral shapes appear to be in motion, even though they are stationary.

The specific patterns used in versions of the Expanding Flower Illusion and the precise mechanisms behind the Troxler Effect are still the subject of ongoing research and investigation. However, this illusion highlights the dynamic nature of our visual perception and how our brain can create illusory motion or changes in size based on the information processed in our peripheral vision.

How does the Expanding Flower Illusion Work?

The Expanding Flower Illusion, also known as the Troxler Effect, is a perceptual phenomenon that arises from the interaction between the visual system and the way our brain processes information from the periphery. Here’s an explanation of how it works:

  1. Peripheral Vision: Our visual system consists of two main components: central vision and peripheral vision. Central vision provides detailed and focused information, while peripheral vision captures a wider field of view but with less detail.
  2. Stabilized Fixation: In the Expanding/Contracting Motion Illusion, you focus your gaze on a central fixation point, keeping your eyes fixated on a specific location. By stabilizing your fixation, you ensure that your central vision remains fixed while the periphery is engaged.
  3. Peripheral Processing: The peripheral shapes or objects surrounding the fixation point fall within your peripheral vision. The visual information from the periphery is not processed with the same level of detail and precision as central vision.
  4. Neural Adaptation: When you fixate your gaze on the central point, the neural responses of the cells in your peripheral visual system adapt and decrease over time. This adaptation reduces the sensitivity and accuracy of the peripheral vision response to static stimuli.
  5. Perception of Motion: Due to the reduced neural responses and adaptation in the peripheral vision, the peripheral shapes appear to be in motion. This perceived motion can manifest as expansion (growing larger) or contraction (shrinking smaller) of the peripheral shapes, even though they are actually static.

The Troxler Effect demonstrates how our visual system prioritizes information from the central vision and adapts to reduce the processing of static peripheral stimuli. This adaptation, combined with the natural tendency of our brain to fill in missing information, leads to the illusory perception of motion, expansion, or contraction of the peripheral shapes. The exact mechanisms and neural processes involved in the Troxler Effect are still the subject of ongoing research and investigation in the field of visual perception.

Some Similar Illusions

There are several illusions that share similarities with the Expanding Flower Illusion or the Troxler Effect in terms of creating illusory perceptions of expanding or contracting motion. Here are a few examples:

  1. Motion Aftereffect (Waterfall Illusion): When you view a moving stimulus, such as a waterfall or a continuously rotating pattern, and then shift your gaze to a stationary scene, you may perceive an illusory motion in the opposite direction. This illusion arises due to neural adaptation, where the motion-sensitive neurons in your visual system become fatigued and respond less to the stationary scene.
  2. Enigma Illusion: In this illusion, a central shape surrounded by a pattern of radiating lines appears to expand or contract when you move your eyes or shift your attention to different regions of the image. This illusion exploits the interaction between eye movements, attention, and the perception of expanding or contracting motion.
  3. Kitaoka Rotating Snakes Illusion: This illusion consists of a pattern of interlocking curved lines that appear to rotate or undulate in a circular motion, even though the lines themselves are static. The perceived motion arises due to the arrangement and curvature of the lines, which stimulates motion-sensitive neurons in a way that creates the illusion of rotation.
  4. Scintillating Grid Illusion: In this illusion, a grid of intersecting white lines on a black background creates the perception of faint gray dots at the intersections. When you shift your gaze across the grid, the dots seem to appear and disappear, giving the illusion of motion. This illusion involves interactions between the receptive fields of retinal ganglion cells and lateral inhibition processes.

These illusions, like the Expanding/Contracting Motion Illusion, involve the manipulation of visual cues, neural adaptation, eye movements, and contextual factors to create the perception of motion or changes in size that are not actually present in the stimuli. They highlight the intricate ways in which our visual system can be deceived and how our brain interprets visual information to construct our perception of the world.

Discovery of the Expanding Flower Illusion

The Expanding Flower Illusion, also known as the Troxler Effect, is named after Swiss physician and philosopher Ignaz Paul Vital Troxler. Troxler first described the phenomenon in 1804 in his publication titled “Über das Verschwinden gegebener Gegenstände innerhalb unseres Gesichtskreises” (On the Disappearance of Given Objects within Our Visual Field). Troxler’s work shed light on the phenomenon of perceptual fading or disappearance of visual stimuli when fixating on a central point, leading to the discovery of the Expanding/Contracting Motion Illusion.


References and Resources

In addition to the Expanding Flower Illusion, check out our complete list of illusions and this awesome similar illusions: Platform 9 3-4, Moving Diamond, Moving Ball, Scintillating Stars, Circle Spiral, Moving Hearts

Expanding Flower Illusion