How Does the Brain Put Faces Together?

Faces. Everybody has one, including you. By the time babies are 2–4 months old, they start to recognize familiar faces, such as those of their caregivers. By now, you probably have many faces that are familiar to you: family members, friends, teachers, and people who live and work in your community. How can we recognize which faces belong to people we know? How can we look at a face and tell when someone is happy or angry?

To do these things, we rely on a specific part of the brain that focuses on recognizing faces. This part of the brain is called the fusiform face area (FFA), and it is found in the fusiform gyrus (Figure 1). There are actually two fusiform gyrus regions in the brain, one on each side. The fusiform gyri are part of larger brain regions called the temporal lobes—also found on both sides of the brain. The fusiform gyrus helps us recognize faces and bodies. This area allows us to put difficult information together, kind of like building a puzzle, which comes in handy when we are trying to recognize the person in front of us. The FFA helps us to recognize whether we are seeing a face, to put parts of the face together to make a whole face, and to determine if the face is familiar or not. Scientists found the FFA using a brain-imaging technique called functional magnetic resonance imaging (fMRI) [1]. Using this technique, scientists saw the FFA “light up” when the person being imaged saw a face. The FFA reacts strongly to a wide variety of faces and helps determine who the face belongs to. The FFA reacts to the entire front of the face, to specific parts like the ears and lips, and facial curves like the cheekbones. The FFA puts the various parts of the face together to form a whole (Figure 2). Studies of the fusiform gyrus and its connection to recognizing faces are relatively new, and scientists continue to work together to find out more about this area of the brain.

Prosopagnosia—Face Blindness

We take it for granted that the FFA will do its job so we can recognize faces, but this is not always the case. Around 2% of the U.S. population experiences prosopagnosia, which means they cannot recognize familiar faces [3]. Face blindness affects a person’s ability to detect their caregivers’ faces, friends’ faces, and even their own faces. It is important to note that prosopagnosia does not affect the visual system. So, the people who have this condition can still see, they just cannot recognize familiar faces. This can be quite scary; however, those who have prosopagnosia can rely on other senses to recognize their loved ones such as remembering the way they move, recognizing their scents, or listening to their voices.

People with prosopagnosia are usually born with it, and it affects their ability to interpret facial expressions, judge someone’s age or gender, or follow where people are looking. Those with this condition might also deal with other mental health issues, such as social anxiety or depression [3]. Social anxiety could happen when people with prosopagnosia are seen as rude because they cannot recognize others, for example. Depression may develop because some people with prosopagnosia have a hard time building bonds with others. Furthermore, prosopagnosia can also affect people’s ability to recognize objects or places, making it hard to figure out where they are or where they want to go. This condition can affect people’s daily lives quite a lot. Things that you find easy to do, like watching a movie, might be hard for a person with prosopagnosia because they find it difficult to recognize characters and understand the plot.

Types of Prosopagnosia: How Is the Brain Affected?

Scientists have determined that there are two types of prosopagnosia: developmental and acquired. Scientists used to believe that prosopagnosia only developed after the brain was injured, but more recently they have found interesting cases in which people are born with this condition [3].

In developmental prosopagnosia, brain injury does not play a role. So, people with developmental prosopagnosia could be born with the condition, possibly because the FFA does not work the way it should. If people develop prosopagnosia when they are born, most do not even know they have an issue recognizing faces. This kind of prosopagnosia is currently believed to be linked to genes because several family members often have this condition [2]. Other types of developmental prosopagnosia happen when children do not develop the ability to recognize faces over time.

Acquired prosopagnosia occurs after a person’s brain is hurt in an accident or when the brain changes due to aging. For example, prosopagnosia can occur from a traumatic brain injury, stroke, or in age-related diseases like Alzheimer’s. This type of prosopagnosia is not very common, and those affected usually know they have suddenly lost the ability to recognize faces [2]. When children acquire prosopagnosia due to brain injury before their brains fully develop, they might not even realize that they cannot recognize faces as well as others can [3].

Treatment: How Do People Live With Prosopagnosia?

Although prosopagnosia is often referred to as face blindness, individuals with this condition can still see the parts of every face they see. They can see the color of the person’s eyes and the shape of their nose, but because they cannot piece together each element of the face, they find other ways to recognize their family members and friends. For example, they might pay close attention to the way certain people dress or style their hair, or the sounds of people’s voices [4]. Just like knowing that your mom likes to wear dresses can help you recognize her from far away at the grocery store, people with prosopagnosia can use clothes as cues to recognize others. These cues can be tricky to rely on, since people often switch styles from one day to another, or get haircuts. Still, people with prosopagnosia learn to adapt to these changes.

Currently, there is no treatment for prosopagnosia; however, researchers are trying to better understand the condition so that a treatment may one day be possible. There are therapies that focus on strengthening the ability to recognize faces, however [3]. Despite the lack of treatment, those affected by prosopagnosia often overcome the challenges they face by using the strategies we have mentioned, or using their other senses. The downside is that these strategies cannot be applied to strangers or someone who is constantly changing, like a kid going through puberty who has dramatic voice changes.

Conclusion

The ability to recognize the faces of our loved ones is something that most of us take for granted. We might not even realize that, in the split second when we look at someone, our brains put together many pieces of information to process the person’s face. The area responsible for making this possible, the fusiform gyrus, does so much for us—even if we do not realize it. Advances in technology constantly aim to make people’s lives better, including the lives of people with prosopagnosia. For example, research is investigating the possible use of lasers to help reverse prosopagnosia in people who get it due to accidents [5]! These and other future advances may help people with prosopagnosia to recognize faces more easily, which may help them in many of their daily interactions with others.

Glossary

Fusiform Face Area (FFA): ↑ A part of the brain that is responsible for facial recognition. The FFA is located in the brain’s temporal cortex, specifically within a part known as the fusiform gyrus.

Fusiform Gyrus: ↑ Section of the brain responsible for recognizing faces.

Temporal Lobe: ↑ Part of the brain that processes feelings, language, and sight.

Functional Magnetic Resonance Imaging (fMRI): ↑ A way to look at brain activity to figure out which areas of the brain are active.

Prosopagnosia: ↑ A condition in which people cannot recognize familiar faces, including their own.

Developmental Prosopagnosia: ↑ A type of face blindness that is often present at birth and likely related to genetic factors or issues with the structure or function of the fusiform face area.

Acquired Prosopagnosia: ↑ A type of face blindness that occurs after an injury or due to age-related changes or diseases such as Alzheimer’s.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.