“Everything we perceive is inconsistent with the physical reality of the world,” Dr. Purves said. “Everything we see, whether it’s line length, color, brightness, you name it.”
So, you are not really being tricked; instead, visual illusions help reveal what our mind’s eye is up to by showcasing mismatches between what we see and what is really out there.
One hypothesis, Dr. Laeng said, is that the brain is trying to predict and show us the future.
It takes time for a stimulus, like light, to reach our sensory organs, which need to send it to the brain, which in turn needs to process, make sense of, and do something with that information. And by the time our brain catches up with the present, time has already moved forward, and the world has changed.
To get around this, the brain may be constantly trying to predict a little bit into the future in order to perceive the present.
Seeing the expanding hole illusion is not a flaw, but a feature: It’s the result of your brain’s strategy to navigate an uncertain, ever-changing world, most likely built up from evolutionary history to ultimately help humanity survive. It is adaptive to predict the future by, say, dilating your pupils in anticipation of going somewhere dark.
“It’s a very philosophical question,” Dr. Laeng said. “We do live in a virtual reality, but it’s a pragmatically useful virtual reality.”
So, the world you are seeing is an illusion, but don’t be alarmed.