In one episode of The Good Wife series, a crime witness is asked to identify the perpetrator (they are of different races) and the witness managed to pick up the wrong one. In the end of course they find out the right perpetrator, but an investigator for the law firm finds out about interracial facial recognition or cross-race effect.
Basically speaking, normally people of a one race have trouble identifying faces of people from a different race (unless they've spent much time with the people of that certain different race). It has happened to me and R2 as well.
When we were watching Ip Man, R2 stated, "I really like watching Asian martial arts movies, but my problem is that they all look the same and it's hard for me to remember which is which." Yep, I can understand his problem, especially during fast action scenes when many people are fighting one another and there are many people involved in the fight/war/battle. And in some Asian action movies, the pace of the movie is very fast, so it's kinda hard to distinguish which is which if you're not used to Asian faces.
When I first started helping out at the daycare, I also had the same problem in remembering the kids. Mind you that there were only about max. 15 kids in the class per day (normally between 10-12 kids at once), but some days some kids didn't come or they came earlier than the others and vice versa. Thankfully they had put the pictures of each kid in the hall along with their names below it, so I took a pic of that with my mobile phone and at home I tried memorizing the faces and the names so that I wouldn't mix them up. After all, some kids had certain needs and if I didn't remember which was which, there would be trouble.
My Japanese friend has also told me a similar problem. She's volunteering in schools in this area and she's been to many different schools and she's met so many different teachers, but the problem is that she doesn't remember which is which anymore - except perhaps the ones that she's met the most.
That's also my problem when I started working in my current workplace. Let's just say that approximately on a 6-hour shift as the main cashier, there are at least 200 transactions (during high season the number can even be over 300 transactions). In the beginning everything just whizzed by, but after some months I started remembering the regular customers' faces.
At my workplace, every now and then, a certain customer wants us (the cashiers) to hold a certain product for him/her to pay later during the day or even the next day. Many times over I can't even remember the person who's booked that certain product, but fortunately normally I'd ask them to write their names down and then they do come back and let me know in detail about what they want.
Another type of problem that I encounter sometimes at work: I remember one day a grandpa came by and said, "Remember me? I came here yesterday." Errrrrrrr...that's a really tricky question. Unless something remarkable or weird or crazy happened when he was there and unless he was a regular customer, I would probably forget about him...but then again it made me feel kinda sad that he was hopeful about my remembering his face he he...Ahhhh...life oh lifeeee...Now I'm rambling...