During my first go at ADHD diagnosis years ago, I discovered that my visual memory ranked in the 7th percentile. I knew that I always had a difficulty recognizing people, but this confirmed it. I didn’t realize that I was so awful compared to other people. I know that I rely heavily on variable things (hair, glasses, clothing, and especially context). For instance, if I see someone who I know well, in a city 500 km away, they’ll ‘remind’ me of that person, but I won’t know for sure. The odds of that person being here are so low. However any normal person would just instantly recognize that person.
If someone I know changes their hair, wears contacts (instead of normal glasses), or other changes - I’ll struggle. I’ll think that I’m right, but I don’t always feel confident enough to say yes, that’s the same person.
Edit: Apparently someone pretty much wrote my post for me already 6 years ago - http://www.addforums.com/forums/showthread.php?t=116521