Being blind to faces?

Well, I myself am well able to recognize faces and distingue them from other stuff, like wardrobe or household items.

But I can’t distinguish between different faces very well.

Yesterday I took part in a pilot experiment of a college. My task was it to do the N-back task with faces. The N-back task works the following: You are presented pictures of faces, one after each other. If you see the same face twice, with one other face in between, you should press a button. E.g. if the sequence is A, B, C, B, D, B, D, A, B, C, B a button press should follow at every “red image” A, B, C, B, D, B, D, A, D, C, B.

The task itself was not supposed to be difficult. My colleague wanted to modulate the response time / accuracy by other means. For me however, the task was impossible to solve, because all faces looked the same.

It was actually quite surprising to see that one should be able to distinguish these faces. I always knew that I was terrible at that – that I can’t watch (or understand) movies because all the actors look the same and I have no chance to distinguish them – but I did not know that other people get an impression of a face within like 2 seconds or so.

So I thought, it might be interesting for other people if I try to explain "how" I see faces:

The strange thing is I am able to distinguish different persons from one another – if I have had sufficient training time. People have a lot of characteristics that are not bound to their face: like their voice, their build, and their style of clothes (or the specific clothes they wear), or – quite close to the face but still good hints – their hair color and length: Once a colleague of mine, who used to have a beard, removed it. That confused me a lot. I knew it was his voice, but he didn’t look like him. It took me half a day or so – and others calling him his name – to figure out that he was still him, despite the change in appearance.

Some might think: Well, if the removal of his beard confused you so much, than you must have remembered his face, with his beard, to be confused about that in the first place. And that is true, but I think I probably remembered just his beard and not the rest of his face and that is, why he didn’t look at all like him, once he removed his beard.

Other people however, can change their facial hair without me even noticing. A little unfair, I know, but I just recognize them by something else than their facial hair. My father for example has an enhancement (pimple like but permanent) right at the tip of his noise. A feature I liked as a child, because it made him easier distinguishable from all the other men: I knew the man with this nose was my dad.

For other people I don’t know how I recognize them – and if I don’t know them quite well, there is a high chance I don’t recognize them at all. Or I may think two "totally different looking" persons were one and the same (which can be quite confusing), until I notice the difference. Then the difference between the two people becomes obvious to me aswell, leaving me wonder why I didn't see the obvious before.

However, with enough time to learn, I’m not unable to memorize faces, or the visual pattern that makes a face. It is just not easier for me to learn “a face” than to learn another pattern of similar complexity. Houses for example, seem to me a lot easier to distinguish than people, but maybe that is just because they are. What do I know? But take brains for example. Most people wouldn’t say brains, or anatomical pictures of brains are easy to distinguish from one another. I wouldn’t say that either. But contrary to the belief of some, they don’t look all the same. There are substantial differences, maybe even more than in faces, yet they can be difficult to detect – just like differences in faces.

Now for me it would be interesting to know who other people (in their own subjective experience) distinguish different faces from one another.


P.S.: I'm just speaking about myself, not anyone else. 
Unfortunately  have not yet read the book by Oliver Sacks.