As social creatures we need to recognise each other and our mind can perform some astounding feats when it comes to recognising faces. If you saw QI a couple of weeks ago then you will have seen the splendid Einsteins face illusion which demonstrates this quite clearly. (You can watch it again here)

We recognise faces with ease – from any angle – even if someone has changed something about their appearance like their hair. According to scientists we use internal 2-D snapshots from our eyes to build and store a 3-D mental representation of the face, which is resilient to such changes. We’ve all had those embarrassing moments when we’ve not noticed a friends new hair-do so maybe that explains why! This is a totally automatic process and happens out of our awareness but is problematic for those with a condition called prosopagnosia which causes a kind of face blindness and affects the ability to recognise faces.*

We are so hard wired to recognise faces that we can see them anywhere – you only have to look up in to the clouds or peer into the shadows to start seeing faces for yourself. And we still understand them even when they are disjointed. This was famously demonstrated by the “Thatcher effect” illusion by Peter Thompson, (1980) when he kept the mouth and eyes the right way up in the otherwise rotated face of the then PM.

You can see it and rotate it here.

I have had to draw a few faces in my time and often turn them upside down to get a different perspective but what’s so weird, is that with a normal drawing I don’t get the strange feeling of something clicking in my head, that I do when rotating this illusion.
It’s a very odd feeling – use the link above and gradually rotate it and you’ll see for yourself.

As with so much to do with brain function it may take a while before the scientists can tell us exactly how this illusion works but for now there are several theories and if your interested there’s a list of them on the “Bang Goes the Theory” site. Apparently People with prosopagnosia  pick up more quickly on this illusion than the rest of us so it must therefore have some connection to this 2D to 3D processing ability.

Our brain gets important information for face recognition primarily from around the eyes and secondly from the mouth and nose which I think is one of the reason why the illusion works – because the most important features remain the correct way up and it only looks strange when they are inverted.

Thought I’d try out the look on our current PM…..
YIKES!

Thatcherised Cameron – Image on the left has been ‘Thatcherised’

Same two images turned the correct way up!

*Read the full article: Brain Needs to Remember Faces in Three Dimensions
David Cameron image from Wikipedia, image manipulation by me.