Optical illusions can easily bewilder individuals. As history has shown, these illusions tend to appear distinct based on one's viewing perspective. However, what occurs when two people see dissimilar things?
One image shared on Twitter has left many individuals stumped. The image showed a black-and-white circle containing a concealed number.
At first glance, one might see the number as 45283, but upon closer scrutiny, it appears as 3452839 – at least to some viewers.
The tweet posted by the user/benonwine garnered a significant 4,000 comments, leaving many social media users left baffled by it
One person commented: My old eyes can only really detect the middle three numbers…I can barely tell that there is one more on either side BUT that I see them at all is due to reading the article and straining to make them out.
A second wrote: If you hold your phone flat you can easily see the middle numbers. The end numbers are slightly cropped out.
A third said: At first glance 1528 but if I focus on each end, I can clearly see it's a 4, not a 1 and there's a 3 after the 8. So 45283
Someone else wrote: 528 but longer I stare 1528
This type of illusion assesses a person's contrast sensitivity.
Contrast sensitivity measures the level of contrast required to detect an object, such as the numbers in the aforementioned image.
According to the Vision Center, contrast sensitivity is a significant aspect of visual capability.
The website said: "Contrast sensitivity is the ability to distinguish between an object and the background behind it.
"Contrast sensitivity is different from visual acuity, which measures how clear your vision is at a given distance."
The Vision Center further explained that detailed features like sharp edges, facial features, and the like are formed by high spatial frequencies.
On the other hand, low spatial frequencies create more overall images, where the overall shape of an object is visible, but not detailed features.
It added: "A contrast sensitivity test measures how well you can tell the difference between light and dark.
"For this, your doctor will use a different type of chart where the characters fade from black to grey gradually.
"Visual acuity is measured when you read the eye chart during an exam."
This case involves a high-contrast test, with black letters presented against a white background.
