Why You Can’t Recognize Other People’s Faces

Have you ever failed to recognize a close friend or family member, particularly when you see them unexpectedly or after they’ve had a haircut?

If so, you might have face blindness—officially called prosopagnosia, from the Greek word prosopon, meaning face, and agnosia, meaning ignorance. As many as 1 in 50 people have some degree of prosopagnosia, although many lead normal lives without even realizing they have it. Here’s what you need to know about face blindness.

How can you tell if you’re face blind?

Symptoms vary widely among those with the condition. Some may find it hard to recognize facial expressions in other people. Watching TV or movies can be a daunting task, as those with the condition may struggle to remember who the different characters are. When meeting a new person, people with face blindness may also try to remember their clothes or hairstyle instead of their face.

Not surprisingly, another trait that typically goes along with face blindness is social anxiety. Failing to understand facial expressions can lead to a difficulty forming relationships or making friends. People with face blindness may avoid social interaction, develop social anxiety disorder and even experience periods of depression, according to the National Health Service in the UK.

Heather Sellers, author of a book called You Don’t Look Like Anyone I Know, told TIME in a 2010 interview that having prosopagnosia feels like having a learning disability. “It’s like dyslexia,” she said. “I know what a face is, but it’s really hard to read faces. [With dyslexia] you know what the word is, but you are going a lot more by context and takes a lot of work [to figure it out]. It feels like walking uphill into the wind.”

Why do some people have face blindness?

Studies show that face-blindness is not connected to general intelligence or wider memory. It is usually a lifelong problem, and developmental prosopagnosia—which refers to face blindness without having brain damage—is the most common kind. It was found to be highly heritable in a study led by a team of German researchers in 2006. One of the study’s authors, Dr. Thomas Grüter of the Institute of Human Genetics in Germany—who himself is a prosopagnosic—speculated that the condition may be caused by a defect in a single dominant gene. This could mean that if one parent has developmental prosopagnosia, their children would each have a 50% chance of inheriting it.

Studies suggest that around 2% of people show signs of developmental prosopagnosia. Some people also develop prosopagnosia after suffering damage to their brain, such as a head injury or a stroke. This is known as acquired prosopagnosia and is relatively rare.

How do you treat prosopagnosia?

Unfortunately, there is no specific medication or therapy to treat prosopagnosia. Some people with the condition develop strategies to help them cope, such as recognizing a person’s voice, hairstyle, dress or gait, or avoiding places where they are likely to run into people they know. However, these techniques are not always reliable or realistic.

Other strategies known to be helpful to prosopagnosics, documented by the University of Minnesota’s College of Education and Human Development, include creating “secret signs” with friends and carrying around a notebook to record details and names of people.

Many people lead ordinary lives without realizing they have the condition, but for the curious, there are various tests to determine whether you show symptoms of prosopagnosia, including Test My Brain’s seven step test and troublewithfaces.org’s 20-step prosopagnosia questionnaire.