Flash Lag Illusion

The flash lag illusion is a visual illusion that is based on the perception of the temporal relationship between a moving object and a flash of light.

The illusion occurs when a moving object is followed by a sudden flash of light, and the perceived location of the flash appears to be behind the actual location of the object.

Flash Lag
From Wikimedia Commons


Table of Contents

How does the Flash Lag Illusion work?

The flash lag illusion occurs because the visual system processes the moving object and the flash of light separately, and there is a delay in the processing of the flash. This causes the brain to perceive the flash as if it had occurred at a point in the past, behind the position of the moving object.

The flash lag illusion is considered as a temporal illusion, where the perceived timing of events is affected by the spatial relationship between the events. It has been used to study the neural mechanisms underlying visual perception, attention, and the temporal properties of visual processing.

The shift is greater for faster-moving stimuli and for stimuli that are closer to the point of flash onset.

In summary, the flash lag illusion is a visual illusion that occurs when a moving object is followed by a flash of light, and the perceived location of the flash appears to be behind the actual location of the object. This illusion is caused by the delay in the processing of the flash, and it has been used to study the neural mechanisms underlying visual perception, attention, and temporal properties of visual processing.

Versions of the Flash Lag Illusion

The following is an alternate versions of the Flash Lag Illusion:



Flash Lag
From Wikimedia Commons




Illusions like the Flash Lag Illusion

Color illusions work by exploiting the way that the human visual system processes color and light. The human eye is able to detect light in the visible spectrum, which consists of different wavelengths of light that correspond to different colors. The brain then interprets this information to create our perception of color. However, the way the brain perceives color is not always a perfect representation of the physical reality.

There are several factors that can influence the way that the visual system processes color and light, which can lead to the perception of illusions. These factors include:

Contrast: The way that the brain perceives color can be influenced by the surrounding colors and patterns. High-contrast borders around an area of color can cause the brain to interpret the color as spreading or “bleeding” beyond the actual boundaries of the object.

Lighting conditions: The way that the brain perceives color can also be affected by the lighting conditions. For example, when an object is viewed in bright light, the eye’s color receptors may become fatigued, causing the brain to perceive colors differently than they actually are.

Color adaptation: The brain adapts to the colors that we see over time, which can influence the perception of color. For example, if an individual looks at a red object for an extended period of time, the brain will adapt to the red, and when that person looks at a white object, it will appear to have a pinkish hue.

Color constancy: The brain is able to adjust the perception of color based on the context in which it is viewed. This can create illusions where the same color appears to be different depending on the surrounding colors.

Shape use: Some illusions like the Hermann grid illusion or the Cafe Wall illusion, use specific patterns and shapes to manipulate the perception of color and shape.

Some related illusions include the following:

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 Hermann Grid Illusion: This illusion is created by the way the brain perceives intersections of lines. When the intersections of a grid of lines are viewed, small gray dots appear at the intersections, even though they are not actually there.



Hermann Grid

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 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-Mach-bands-wiki.jpg


The Ishihara Illusion: This illusion is created by the way the brain perceives colors. When a color is surrounded by a contrasting color, the brain perceives the color to be different than it actually is.

Ishihara Plate 9
From Wikimedia Commons

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 Flash Lag Illusion

The phenomenon was first described by Nijhawan (1994) who found that when a moving stimulus is followed by a flash, the perceived position of the flash is shifted behind the position of the moving object.

References and Resources

Check out our complete list of illusions.