"It'd be awkward"

Even if they don't know, there's the moment. You picture saying "you handled that really well" and your whole body objects. It sounds stilted. There'd be a pause. They'd look at you. One of you would have to say something afterwards, and neither of you would know what. That's the squirm, and it's real, and it arrives before you've said a word.

The question is whose it is. Zhao and Epley measured this too. In the same nine experiments, the compliment writers predicted how awkward the recipient would feel, and they overestimated it. The recipients felt less awkward than the writers expected. Erica Boothby and Vanessa Bohns ran five studies of their own, published the same year, and found the same thing from a different angle. Compliment givers overestimated how bothered and uncomfortable the recipient would feel. In one of their studies, the givers still overestimated it after the compliment had been given, looking back on it. The squirm didn't just distort the guess in advance. It coloured what people thought had happened.

There's a detail in the Boothby and Bohns work that I think matters most. They asked people who weren't giving the compliment, third parties looking on, to predict how the recipient would feel, and those people got it about right. The people who got it wrong were the givers, and what drove them wrong was their own anxiety and their worry about doing it well. The squirm isn't a reading of the room. It's a reading of you.

So here's what I'd say the squirm is. It's a feeling you have about a thing you're about to do, and it's loud, and it belongs to you. It doesn't cross the room with the words. What crosses the room is "you handled that really well", and what the other person does with that is feel better than you expected, by a margin that turns up in study after study.

That leaves the pause. Yes, there might be one. They might say "oh, thanks" and look at the floor, and you might not know what to say next. I'd suggest you don't need to say anything next. You said the thing. The pause is the sound of it landing, and it's a good deal shorter than it feels from your side.