If you can see a smiling or grimacing face on the side of the cheese grater in the photograph you are far from alone.  The phenomenon of seeing faces in everyday objects is called pareidolia, and it shines a light into how our brains and minds work.

You’ll have probably come across examples of wood grain patterns, pieces of toast, or clouds in which people see likenesses of the Virgin Mary, Jesus, or Mother Teresa.  Our brains have evolved to see patterns and meaning, and pareidolia, imposing the pattern of a face on random or ambiguous shapes, is perhaps the most specialised example of this.

From the moment we are born our ability to distinguish a face from other things that we see runs ahead of many of our other mental abilities.  At the age of five months we will recognise pictures of people’s faces as being faces, but without being able to recognise different emotions in facial expressions.  At the age of seven months however we will focus more on an angry or fearful face than one that is happy, evidence of not just increasing skills but also how we use them to help us assess potential threat.

The area of the brain where this processing is carried out is the fusiform gyrus, and it can distinguish a face in just under a fifth of a second.  In fact it is so sensitive that it will recognise objects that might look like faces, like light switches, almost as quickly.  Even when you know they aren’t faces, such as the cheese grater, your brain still processes them through the fusiform gyrus, giving pareidolia it’s persistent effect.

The extent to which we depend on our facial recognition can be seen in people who have prosopagnoasia – the inability to recognise faces.  It used to be thought that this was normally the result of brain injury, but now it’s suspected that up to 2.5% of the population might be born with the inability.  Ironically people with the condition include the photorealist portrait painter Chuck Close, and Jane Goodall who lived amongst and learned to distinguish individual chimpanzees in Tanzania.

Because of the role of the face in social situations and memory formation prosopagnoasia can make relationships more difficult.  Whilst there’s no effective therapy prosopagnosics  develop a variety of coping strategies.  They may memorise individual features to aid recognition, look for secondary characteristics such as hair colour, build and voice.  They may also use body language, tone of voice, and the content of speech to recognise emotion.

So next time you see a chicken nugget that looks like Abraham Lincoln you’ll know why.

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