humans are irrational humans are irrational What kind of message is your face sending? A new study takes a deeper look. (Photo: Arthimedes/Shutterstock)

Here's what happens to your brain when you see someone's face for the first time

We scan some faces differently than others. A new study shows us how, and why.

It's true what they say: Every face tells a story. Olivia Newton John even sang it in 1976 (yes, I Googled it). It's also a popular tagline for skincare advertisements, but that's another matter altogether.

In a new study led by a Hebrew University professor in Israel, the human brain underwent a deep dive to find out just how it processes faces. The gist? There are two perceptions: dominance and trustworthiness. That means that many times, before we even meet a person – if we ever meet them at all – we've decided whether we can trust them, or if we think they'll be a threat.

The research, published in the journal Nature with collaborations from Princeton University professors, lays out why some faces stand out to people and some don't. It also examines whether we can control those perceptions in order to understand which features trigger certain attributes.

For example, said lead author Ran Hassin, "faces with bigger eyes are perceived as more trustworthy."

close-up of woman with blue eyes Your eyes offer big clues about how you're feeling. (Photo: SerdyukPhotography / Shutterstock)

To conduct the research, Hassin and colleagues exposed participants to 300 sets of rapidly changing images. In one eye, participants were exposed to images of human faces, and in the other eye they were exposed to geometric shapes. The participants were then asked to press a computer key as soon as they saw a human face.

Sorting out all that stimuli took the brain a few seconds to understand that it was seeing a face. But once it did, it transferred the images to the conscious brain for processing. The researchers observed that the facial dimensions that were most quickly registered by participants were ones that indicated power and dominance.

"This study gives insight into the unconscious processes that shape our consciousness," Hassin said from his office in Jerusalem. "These processes are dynamic and often based on personal motivation. Hypothetically, if you're looking for a romantic partner, your brain will 'see' people differently than if you're already in a relationship."

Rotem Sela and Aviv Alush in a scene from "The Baker and the Beauty." If only all couples looked at each other like this. (Photo: Keshet)

This could have implications in the study of behavioral and mood disorders, he said.

"It might be possible to train and untrain people from perceiving certain facial dimensions as threatening," Hassin concluded. "This could be helpful for those suffering from PTSD or depression. Likewise, we could train people with autism to be more sensitive to social cues."

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Here's what happens to your brain when you see someone's face for the first time
We scan some faces differently than others. A new study shows us how, and why.