Calming signals are emitted in situations of social conflict, and they have a calming effect on the recipient – at least in dogs. Humans mimicking the animal’s behaviour may do the same – at least in chimpanzees.
Here’s the blog post about body language:
Rachael Draaisma’s communication ladder is here.
And find Janneke Koekhoven’s poster Calming and Stress Signals in horses here.
I don’t think that cats’ slow blinking has been called a calming signal, but recent research has shown that humans slow blinking at cats are more likely to be approached than if they have a neutral expression.
“Shut down” is a label that can involve learned helplessness, apathy, unresponsiveness, disengagement…
Jenny made an important comment related to how people make use of calming signals: Dogs “communicate” by sending calming signals to each other. And we can teach them to communicate this way by putting them in situations where they can practice these calming signals. IF calming signals mainly are the animals physical response to distress, I think this is questionable training, ethically.