If you weren't able to spot the tricky letters at first glance, your efforts were not in vain! According to University of Sydney scientists Kim Ransley and Alex O. Holcombe, optical illusions are vital for researchers that work to understand the inner workings of our most complex organ -- the brain.
In an article for The Conversation, the scientists explained that "visual illusions show us that we do not have direct access to reality" and added that, "They can also provide an inkling of the mental processing that delivers our experience of the viewable world."
"Indeed, it is the processing happening inside our brains that is the basis for many illusions," the duo continued. "Rather than delivering information from our eyes in nearly raw form as a camera would, the brain tries to determine what is actually out there."