Can videos of marriage proposals reveal something about the human mind? One psychologist thinks so. He’s been studying YouTube marriage proposals ever since the rise of surprise video proposals became popular, and he’s intrigued by the familiar human interactions that take place in every marriage proposal, most particularly when women cover their mouths.

“Everyone knows the face is an emotional radiator,” psychologist David Rose tells NPR. “It’s a communication system that tells others what you’re thinking. It’s as though the woman is thinking, ‘Oh, my god, this is going deep into my soul, what am I showing here?’ When I see the very few who don’t [cover their mouths], I wonder, what does this mean? Are they unusually non-emotional? Does it mean they don’t care about this guy? I don’t know.”

Another familiar human interaction he picks up from watching proposals is the “embrace.”

“A lot of times the woman doesn’t say ‘yes,’ or it’s not audible,” Rose says. “But you can read her response by the way she reaches out and grabs the man in a very loving hug.”

To be honest, none of his findings are necessarily groundbreaking discoveries, but it’s interesting nonetheless how humans go through the same emotions when going through a proposal. And since we probably watch one too many YouTube proposals ourselves, we can understand that sentiment. What do you think of the popularity of YouTube proposals?