I’ve had several cats in my lifetime, and this behavior has been shown in two of them. The others have not shown it.
Basically it’s this - if you’re petting the cat’s face, you move toward the nose. Using your index finger, you scratch the top of her nose, where the nose meets the rest of her face. If you do this, she will yawn. Every single time.
At least, every single time with one caveat - as long as there’s sufficient “yawn recharge” time. In my current cat, the yawn recharge interval is pretty small. A few minutes seems to do the trick. In my old cat that did this, she required at least an hour to recharge. Then she’d do it again. If you scratch them the same way on the nose twice in a row, it will only work the first time. Once recharged, you’re good to go again.
Also, the old cat started to resist after I did this with some frequency. She would turn her head away when I started, as if trying to say, “Ugh, don’t make me yawn again!” Then when I persisted, she would yawn anyway and look at me with disdain for putting her through such indignity.
Why do they do this? What’s going on with their little goomer brains?