The brain works to process visual input to the level of understanding its meaning even if we never consciously perceive that input, researcher leader Jay Sanguinetti, a doctoral candidate at the University of Arizona, said.
Writing in the journal Psychological Science, Sanguinetti and his colleagues describe their study in which participants were shown a series of black silhouettes, some of which contained recognizable, real-world objects hidden in the white spaces on the outsides.
The participants' brainwaves were monitored with an electroencephalogram, or EEG, while they viewed the objects, revealing a brain signature for meaningful processing.
"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," Mary Peterson, a psychology professor and Sanguinetti's adviser, said.
"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."
These findings raise the question of why the brain would process the meaning of a shape when a person is ultimately not going to perceive it, the researchers acknowledged.
"Many, many theorists assume that because it takes a lot of energy for brain processing, that the brain is only going to spend time processing what you're ultimately going to perceive," Peterson said.
"But in fact the brain is deciding what you're going to perceive, and it's processing all of the information and then it's determining what's the best interpretation."