The cats showed me this things first. Other sources confirmed and explained it. Experience proved it works…
When I first learned about yawning as a way to make headway with feral, or just shy, cats I noticed the cats doing it with each other. It was a tension breaker. When it looked like a fight was going to break out or one was going to try to give the other one a hard time, sometimes the standoff ended when one cat yawned, and then went about its business.
It often looked like a graceful way out of a staring contest. “I’m not giving in, I’m just bored with his shit.” Or maybe, “Yawning forced my eyes shut and now you’ve given up. Oh well.”
Then I read somewhere that the yawn, in cat language, means “I am not trying to threaten you.”
So I started yawning at the feral cats who would come onto the porch and look at me through the window, but scattered when I opened the door. And it worked!
They instantly adopted a more relaxed posture and quit watching me like I was going to come after them at any moment. If they caught me watching them at the food dish, they quit staring and went back to eating.
I couldn’t open the door and walk out with them, that would have been going back on my word, but there was an instant response to the message every time. They went from watching to see if I was going to make a move to carrying on.
I’ll tell you right now that you have to be pretty self-assured to do this in front of people. Yawning looks silly enough, but forced yawning looks and feels ridiculous! And it’s not like you can stop and answer someone in mid-yawn communication with a cat when they ask you what you are doing. If you don’t complete the yawn, it doesn’t really fly. You don’t realize how long a yawn takes until you try to complete your second or third forced yawn while trying to ignore someone and simultaneously not make them feel like you’re blowing them off!