You may be under the impression that it takes weeks of getting to know someone before you can trust them, but your brain has already done the job of decoding their personality within the first second of meeting them face-to-face. In a YouTube video uploaded by SciFri, Dr. Jon Freeman explains how it takes our brain less than a second to identify character traits just by glancing at another person’s face.

“By looking at a face for less than a second, we can judge someone’s age, gender, race, emotional state, and even their trustworthiness,” the video description reads. “High-speed scanning and perception experiments by social neurologist Dr. Jon Freeman have revealed our brain’s ability to generate character assessments in less than blink of an eye. These first impressions can linger in our brains and influence our real-world interactions.”

The temporal lobe is the region of the brain responsible for our ability to recognize faces. Neurons begin firing in the temporal lobe when we see a face. Severe damage to the temporal lobe can result in prosopagnosia, a neurological disorder in which the patient cannot recognize faces. People with prosopagnosia, also known as face blindness, often have trouble recognizing familiar faces, are unable to discriminate between unknown faces, or in extreme cases cannot recognize their own face.