Do you think recognising faces is just something we innately know how to do from the time that we are born?
After all new born babies are known to track faces early in their development, leading to the belief amongst the scientific community that facial recognition is something that our brain does immediately from birth.
But new research shows that facial recognition only forms through experience.
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To better understand the basis for facial recognition, scientists from Harvard Medical School, raised two groups of macaques – a close evolutionary relative to humans, and a model system for studying human brain development.
The first control group had typical upbringing – spending time with their mothers in infancy and then with other juvenile macaques as well as human handlers.
The other group was raised by humans who bottle fed them, played with them and cuddled them. All humans wore a welding mask. For the first year of their life, the macaques did not see a face – human or otherwise.
At the end of the trial all the macaques were put together in a social group with other macaques and allowed to see both human and primate faces.
When the macaques from both groups were 200 days old, the researchers performed MRI to look at brain images and measure the presence of facial recognition patches and other specialised areas such as those responsible for recognising hands, objects, scenes and bodies.
Macaques that had a typical upbringing had formed clusters of neurons responsible for recognising faces in an area of the brain called the temporal sulcus. They also had developed areas in the brain for other forms of recognition.
However, the macaques that had grown up without seeing a face showed development in all areas of recognition except the one associated with facial recognition.
The researchers then showed both the groups images of humans and primates. As expected the control group gazed at faces in the images while the macaques without facial exposure looked preferentially at their hands. The hand domain in their brain was considerably larger compared to other domains.
This study shows that the brain is very good at recognising what an individual’s sees but when it is deprived of sensory experience it has a very selective effect on the brain and it fails to recognise that which it rarely or never sees.
The findings of this study helps to explain a wide variety of disorders, including those in which people cannot distinguish between faces including their own and in autism which is characterised by an aversion to look at faces.
In autism spectrum disorders, this may lead to social deficits which develop as children with these disorders tend to avoid looking at faces.
The findings of this study suggest that early exposure to faces may help mitigate the social deficits that arise from lack of facial exposure.
It seems like the brain memorises the faces that we see since birth and wires it selectively to recognise these faces again in the future. So if we haven’t seen a face for a long time or never, chances are our brain is not going to recognise it.
Source: Nature Neuroscience
