Honest question: These guys mention using the results for research. They must know they are skewing their results quite significantly by singling out anyone who is a) aware that the result of this test can be embarrasing b) not comfortable linking their name to such a test with?

I'd guess according to this test face blindness is far less common than previously assumed : )

As I understood it, they're basically searching for people with prosopagnosia for further research. They also mention somewhere that some people with prosopagnosia can do well in the test (I assume if those people have seen the famous faces enough it can work for light cases.)

I just got two out of 18 that I was familiar with, but I'm not sure whether I was supposed to spend time thinking about it. Sometimes I was sure that I recognised the face, but couldn't place it, and said that I didn't know without really trying.

There were a few that I got wrong after thinking I knew it, and one that I got wrong after rejecting the correct answer as a hypothesis.

V gubhtug Ovyy Pyvagba jnf Fgrira Frntny; Wvz Pneerl jnf gur thl sebz Gur Fuvavat; Tnauqv jnf Rvafgrva; naq V qrpvqrq Znetrerg Gungpure jnf cebonoyl abg Znetrerg Gungpure. Ohg V tbg Xrnah Errirf naq Trbetr Ohfu.