I haven’t done a Brainteaser for a while, so I thought I’d share with you this clip from QI to see how you get on!
What you should notice, is that when the face is pointed towards you, it appears to be 3D and facing you, regardless of whether or not you are seeing the concave side of the image or not.
This illusion is known as ‘cognitively impenetrable’ because no matter how hard we try to see the face as pointing away from us, our brain always shows us the opposite – in this illusion having knowledge of how it works does not affect it at all.
This therefore shows how powerful the illusion is, and as Stephen Fry mentions in the clip, it shows how automatically we perceive faces, and how biased we are to perceive stimuli as faces. (For more information on this topic, check out my post here)
He also mentions that this ability is thought to be innate – babies only a few hours old have shown to prefer to look at images of faces rather than other stimuli (e.g. Batki et al 2000) and look at whole faces, rather than faces with scrambled features (but otherwise identical) e.g Goren et al (1975).
These results show that infants must have some sort of knowledge about faces and social interactions when they enter the world. Further evidence to support this is shown in a famous study by Meltzoff & Moore (1977) in which young infants – only a few weeks old were about to imitate facial expressions – shown in the well-known image below. This shows how important social interactions are to us at such a young age, as they provide the basis for our further development.