To sum it up quickly and easily, face blindness is a condition in which you have great difficulty recognizing people's faces and sometimes other objects, such as cars. I have always had a problem with this. When I was twelve I once passed my mother and a friend of hers on the street. She called out to me and I turned and said, "Mom?". Her friend asked her later if she saw me often.
When I was a young adult my friends used to mess with me in crowded bars and concerts by moving two feet to the left when I wandered off and then had a great time watching me try to find them. I would stumble past them repeatedly, cursing until I finally saw them. A cruel but entertaining drinking game.
It also led to some awkward encounters with guys I had hooked up with and would later not recognize. It made me appear far sluttier than I actually was. Well....not by much.
what you get when you google "80's party chick"
Image from test. Still think it's the same dude in each one.
There's not a lot you can do for face blindness. I recognize people by voices, the way they carry themselves or clothing. I have a hard time with cars as well. My boyfriend once described watching me search for the car. He said I have this confused, annoyed expression as if someone has rearranged the world while I was gone. That pretty much sums up what it's like.
So if I walk past you on the street, I'm not being a jerk. I probably just don't recognize you. Knowing what is wrong has helped a lot.