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Inspired by the perennial, "how do I make friends w/ crows," question I've seen a few people suggest putting pictures of the would-be friend next to the food, as a means of helping the crows make the connection between the food and the person. This won't work. Let me explain why.
As a college Jr. (3rd year) I had just discovered the amazing world of crows and I was determined to design a senior thesis project studying them. Here's me in college, eating a cookie and thinking about crows. (Actually I was studying for a nutrition test but let's pretend)
As it happened, my undergrad advisor was a collaborator on the infamous UW facial recognition study lead by John Marzluff. After reaching out to John to express my interest in crows, he suggested doing a study on whether crows recognize friendly people.
Now, normally, friendly relationships with crows are built slowly over time. I didn't have a ton of time though. So myself and my UG advisor, @DavidPCraig hatched what we thought was a brilliant plan.
We built a life-sized dummy that we set up in a lawn chair w/ a basket of peanuts and in the mask of the politician we were trying to make our crow friend. We figured this would be easy way to fast track a friendship, because they could offer food 24/7.
The crows took to it immediately. IIRC, they started feeding without any hesitation from our fake seated person within a couple days. When we tried to transition from dummy to real person in the mask though, everything came to a grinding halt.
When we put a real person under the mask, the crows were just as wary of them as they were of someone in the control political mask from whom they had never been offered food.
This wasn't an issue of recognition. I know this from the UW study that showed crows can learn and recognize masks.
Instead, this where the intelligence of crows explains why scarecrows don't work. Crows know the difference between an inanimate image of someone and an animate person. And they know that while inanimate photos/dummies are harmless, real people are not.
The linchpin of a friendship with crows is not simply recognition, it's trust. Only the actions of the real person can contribute to that. There's just no short-cutting friendship.
For those wondering if crows can recognize 2D images at all, the answer is yes. In fact the second part of my study was to make a flat mask of a local woman who fed crows every day and a second 2D mask of a rando fellow undergrad.
Unfortunately, I can't recall the specifics of our results anymore but I do remember that the crows showed a preference that indicated they recognized their person even in a 2D image. Also crows can use computers.
Bahaha, sorry, I didn’t realize the computer thing would rattle everyone so much! It’s not unusual to use computers for cognitive tests, because it allows the animals to interact directly without human interference.
So for example when testing whether crows have quantitative reasoning skills, they used computers to quickly cycle through different comparisons, and ask if the amounts were the same or not (I.e. 2 vs 2 dots of equal size, 2 vs 2 dots of unequal size, 2 vs 3 dots, etc).
You can read more about that numerical competency study here: https://corvidresearch.blog/2015/06/11/counting-crows/
By using touch screens, the crows can be easily trained to indicate their choice, again, without the interference of people.
So yeah, they use computers but it’s not like they’re typing up word documents or playing Minecraft. I just meant they can interface with a two dimensional image just fine 
