The mystery behind optical illusions lies in the eyes, not deep in the brain, according to new research.
A recent study from the University of Exeter refuted the idea that these brain waves come from complex psychological processes.
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The bar in the middle of the image is filled with a single shade of gray, and again, the left appears lighter and the right appears darker Credit: Dr. Jolyon Troscianko
Instead, they are simpler than scientists and philosophers thought.
Visual illusions are caused by limitations in the way our eyes and visual neurons work, research has shown.
In a statement, sensory evolution expert and paper author Dr. Jolyon Troscianko said: “Our eyes send messages to the brain, causing neurons to fire faster or slower.
“However, there is a limit to the speed at which they can be activated, and previous research has not considered how this limit might affect how we see color.”
Take the optical illusion above, for example.
The bar in the middle of the image is filled with a single shade of gray.
And yet it looks lighter on the left and darker on the right due to the background gradient.
“This shatters a lot of assumptions about how visual illusions work,” Troscianko said.
But if you’re able to see through the illusion, this latest research suggests you’re particularly aggressive.
Troscianko added that the findings also shed light on the popularity of high-definition televisions that have become the norm in 21st-century living rooms.
“Modern high-dynamic-range televisions produce bright white regions that are more than 10,000 times brighter than their darkest black, approaching the contrast levels of natural scenes,” Troscianko explained.
“How our eyes and brain can handle this contrast is a puzzle because evidence shows that the highest contrasts we humans can see at a single spatial scale is about 200:1.
“Even more confusing, the neurons that connect our eyes to the brain can only handle contrasts of around 10:1.
“Our model shows how neurons with such limited contrast bandwidth can combine their signals to allow us to see these huge contrasts, but the information is ‘compressed’, resulting in visual illusions.
“The model shows how precisely our neurons have evolved to use every bit of capacity.
“For example, some neurons are sensitive to very small differences in gray levels on intermediate size scales, but are easily overwhelmed by high contrasts.
“Meanwhile, neurons that encode contrasts at larger or smaller scales are much less sensitive, but can operate on a much wider range of contrasts, producing profound black-and-white differences.
“Ultimately, this shows how a system with very limited neural bandwidth and sensitivity can perceive contrasts greater than 10,000:1.”
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Categories: Optical Illusion
Source: HIS Education