Here’s a cross-disciplinary thought about how we identify birds: we seem to wrestle between bottom-up and top-down processing. Bottom-up processing of visual information is what we imagine to be our “raw perception”: we sense light with our eyes which we eventually translate into what our brains interpret. It’s the most intuitive and direct model of perception. However, I’ve been talking with birders for years about how we learn to identify birds, and my experiences lead me to believe top-down processing plays in, which is based in cognition instead of sensing.
“Your brain applies what it knows and what it expects to perceive and fills in the blanks, so to speak.” – OpenPSYC
In other words, your brain makes a story given a certain context. This would explain why we think we see things we didn’t see, leading to wrong identifications (especially in those times we’re “sure we saw something else”). Many birders talk about the bias of expecting to see a certain species, so we “see” it. This fits well with an explanation for why we end up misidentifying birds, especially if we already possess some degree of birding skill related to what we’re trying to identify.