Your brain sees things that you don’t

BY newsdesk  November 14, 2013 at 6:08 PM EDT

Image courtesy of Jay Sanguinetti/University of Arizona

Your brain saw something in the black and white image above, even if you didn’t. According to a study published this week in the online journal Psychological Science, the brain processes and understands visual input, even if we are unaware of it.
Jay Sanguinetti, a doctoral candidate at the University of Arizona, showed study participants black and white silhouettes. Some were just shapes, but a few images were outlines of real objects, like the seahorses in the image above. He monitored their brains with an electroencephalogram — which looks like a swimming cap with wires. They were shown the pictures for 170 milliseconds, which is less than a quarter of a second.


A study participant dons the cap used to take EEG scans of her brain activity while she views a series of images in Jay Sanguinetti’s study. Photo by Patrick McArdle/UANews

“We were asking the question of whether the brain was processing the meaning of the objects that are on the outside of these silhouettes,” said Sanguinetti, lead author of the study. “The specific question was, ‘Does the brain process those hidden shapes to the level of meaning, even when the subject doesn’t consciously see them?’”

Sanguinetti noticed a spike in the participants’ brainwaves less than half a second after they saw the silhouettes with hidden images, indicating the brain recognized a shape and associated it with a particular meaning.

“The participants in our experiments don’t see those shapes on the outside; nonetheless, the brain signature tells us that they have processed the meaning of those shapes,” said Mary Peterson, Sanguinetti’s advisor. “But the brain rejects them as interpretations, and if it rejects the shapes from conscious perception, then you won’t have any awareness of them.”

Why does it do this? Think about walking down the street, Sanguinetti said. There are thousands of objects your brain identifies. But you are only aware of a handful of these objects at a time, like the pothole in the sidewalk. The brain is constantly taking in visual input, but it takes energy to process and use that information. So the brain throws out the visual input that it deems unnecessary, Peterson said, and as a result we don’t consciously “see” it.

“This is a window into what the brain is doing all the time,” she said. “It’s always sifting through a variety of possibilities and finding the best interpretation for what’s out there. And the best interpretation may vary with the situation.”

H/T Rebecca Jacobson