It has long been accepted that people and other primates are born with the ability to recognize faces; however, a new study at Harvard Medical School has brought that into question.
The study findings suggest that facial recognition is not innate but is learned
The new study published in Nature Neuroscience worked with macaques that had been temporarily prevented from seeing faces while growing up. The researchers discovered that areas of the brain involved in facial recognition form due to experience and are not present in primates who do not see faces while they grow up. This brings into question the long-held idea that we are simply born with the ability to recognize faces.
The researchers suggest their findings are important for a variety of neurodevelopmental conditions, including conditions in which people struggle to distinguish between different faces, and autism, in which there is an aversion to looking at the faces of others. Perhaps more importantly, the study results highlight the formative role that early life experiences play on brain and sensory development.
Macaques are closely related to humans, and their similarities make them an excellent model to study human brain development. At around 200 days of age, macaques develop clusters of neurons that are responsible for facial recognition. These neurons develop in a region of the brain known as the superior temporal sulcus, which is similar across primate species and should also include humans.
To test and understand the basis for facial recognition, the research team divided the macaques into two groups. The first group was the control group and had a typical childhood, including spending time in infancy with their mothers, other macaques, and human keepers.
The second group was raised by humans who fed the macaques from bottles, played with them and cared for them, but they always wore welding masks to hide their faces. For an entire year, this second group of macaques never saw a face of any kind.
When both groups of macaques had reached 200 days old, the researchers used MRI scans to examine their brains. They searched for the clusters associated with facial recognition, hands, objects, bodies, and so on.
The control group had recognition clusters for each of the search categories in their brains. However, the second group had developed clusters for everything but facial recognition.
Finally, the researchers then showed images of humans and primates to both groups of macaques. The control group predictably focused on the faces in these images, but the second group generally looked at the hands instead. Perhaps more intriguingly, the clusters devoted to recognizing hands in the second group were significantly larger compared to the other clusters.
This research gives us valuable insight into how the brain develops, potentially turns established thinking upside down, and the researchers believe it may help to explain various disorders, such as autism and prosopagnosia, the inability to recognize familiar faces. The research suggests that early exposure to faces may help to combat conditions like these that may stem from a lack of stimuli during early development.
The study results also suggest that sensory deprivation influences the way the brain grows and can literally rewire it during early development. The brain becomes increasingly better at recognizing familiar things than things it rarely or never encounters. Basically, the brain is trained by consistent exposure to the same images and ends up installing recognition “machinery” adapted to that experience.
This is very similar to how machine learning through visual recognition works. Like people and macaques, artificial intelligence-based systems can learn and develop through experiences and stimuli. Researchers are investigating ways to use these systems to speed up the pace of progress in aging research. We are currently hosting the MouseAGE project, which seeks to develop a visual recognition system to judge the effects of rejuvenation therapies on mice.
Perhaps artificial intelligence and studies like this will give us the insight we need to progress faster in aging research in the near future.
 Michael J Arcaro, Peter F Schade, Justin L Vincent, Carlos R Ponce, Margaret S Livingstone. Seeing faces is necessary for face-domain formation. Nature Neuroscience, 2017; DOI: 10.1038/nn.4635