The brain uniquely distinguishes a natural face from a synthetic one produced using artificial intelligence. Surprisingly, even the brain isn't aware of this talent.

Brain Can Tell When Face Is Real Or Not

Synthetic faces have appeared as real and genuine as real ones with artificial intelligence (AI). For instance, ThisPersonDoesNotExist.com has unlimited images featuring people who don't exist in real life.

In a recent study, Australian researchers investigated our capacity to distinguish between synthetic and real faces. Again, online participants in the first trial could not discriminate between the two types of faces and thought synthetic looks were more accurate than natural ones.

Their second trial, though, appeared to provide a different picture. An additional group of participants in the laboratory were instructed to put on electroencephalography (EEG) caps. The electrodes attached to these caps measured the electrical activity in the subjects' brains.

To complete the challenge, participants had to quickly switch between different faces and press a button each time a white circle displayed above the faces became red. Everyone's attention was on the visual in the middle of the screen.

According to the EEG test results, people's brain activity changed depending on whether they were staring at actual or artificial faces. The difference became noticeable approximately 170 milliseconds after the faces initially showed on screen.

A recognized component of the electrical signal called N170 is sensitive to the arrangement and spacing of facial features. Therefore, one explanation could be that people saw subtle differences between synthetic and natural faces, such as the spacing between features like the mouth, nose, and eyes.

These findings imply a discrepancy between what our brains "know" and how we behave. Participants could not consciously distinguish between artificial and real faces, but their brains could, as evidenced by their EEG activity.

Though it would be a shock to consider that our brains can process information outside of our conscious awareness, there are already several instances of this in psychology.

You can try this experiment by checking out these photos. You can find the answers here.

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How the Brain Recognizes Faces

Another study of rhesus macaque monkeys discovered that recognizing faces relies on coordinating a group of hundreds of neurons that pay attention to certain sets of physical features. The results found that each neuron is linked to a "face cell" that pays attention to specific ranked combinations of facial features.

Study co-author Doris Tsao, a systems neuroscientist at the California Institute of Technology (Caltech) in Pasadena, and Le Chang, a neuroscientist also at Caltech, examined the brains of two rhesus macaque monkeys (Macaca mulatta) to determine the cells. Images of human faces or other items, such as bodies, fruit, and arbitrary patterns, were displayed to the monkeys.

They next observed which brain regions illuminated when the animals saw a face using functional magnetic resonance imaging. Between the two animals, they recorded responses from 205 neurons in total. A particular combination of some face factors elicited a reaction from each cell.

The reaction of each face cell in the monkeys' faces stayed the same even when they altered based on traits that the neurons didn't care about.

David Leopold, a neuroscientist at the US National Institute of Mental Health in Bethesda, Maryland, said, "the neuron is not a face detector, it's a face analyzer." He added that the brain can acknowledge the key dimensions that allow one to distinguish one person from another.

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