Short Answer:
Don't mirror body language, tone or facial expressions online. Only do it in person. In text messages, do keep your questions and answers to the same length as the other person.
Long Answer:
No one has answered in nine months, so I thought to respond as a typical neural person. I have a self-identified ASD wife with a highly successful senior executive career in a global company. My answer takes into account having studied her communication style.
Asking bard.google.com what mirroring is (which exactly matches my prior understanding):
In the context of human communication and autism, mirroring refers to the act of copying or imitating the body language, tone of voice, or facial expressions of another person. This is a natural way that people build rapport and connect with each other, but it can be a challenge for people with autism.
My personal experience is that mirroring is an "in-person" technique using body-language. You sit up if they sit up. You write a note in a pad if they do. You cross or uncross your legs to follow them etc. I tend to notice direct mirroring and find it distracting or off-putting. Yet I am rare, and I will explain that point later. I will occasionally mirror but very minimally and only in in-person situations.
With text or video conference communication, I expect mirroring not to work or even be counterproductive. I have no references to support my position but some off-the-cuff points:
Video: I took an "Introduction To Acting" course. My instructor taught me that stage acting requires a lot of body language and non-verbal communication. In contrast, she taught that with TV acting, the media requires subtle facial expressions, and that body language seems over-amplified. Video conferencing is more like TV acting than stage acting. Mirroring facial expressions would be highly unnerving ("robotic" or "creepy"). Mirroring body language risks being unsubtle on video and so "discovered", which may be counterproductive. More on that below.
Text: People are used to communicating non-real-time with people who cannot respond in kind as they are busy or distracted. I wouldn't "mirror" throughout text communication. Yet it is polite to "respond in kind". If someone is chatty and asks, "How was your weekend?" and uses three sentences, then being succinct with a short direct reply seems rude. Likewise, if they are being very brief in their first message to you, then responding with a chatty three-sentence response seems rude. My rationale is that not responding in kind, in either case, is disrespectful of their time. Either the time they invested in being chatty, else the time they could not afford to be talkative, as evidenced by their briefness.
On the video, I would follow the approach outlined for text. That is to “respond in kind” in terms of length and “small talk” in a reflective manner. This is a form of mirroring I guess but not how it is defined above. IMHO neural typical people would see it as “common courtesy” rather than a specific technique.
I mentioned above that I occasionally notice people mirroring and find it distracting and off-putting. I also said above that "being discovered" mirroring may be counterproductive. If I notice someone physically mirroring my body language, I will test for it. I will reverse whatever they reflect only to see if they follow. If someone does seem to be consciously mirroring me, I am instantly cautious of them. This is because mirroring is taught as a sales technique. When I detect mirroring as I suspect someone is trying to manipulate me for financial or political gain.
In conclusion, I recommend the following:
- Do not mirror on video.
- With text messages, respond in kind to brief message. With a chatty initial message, reply to the same length. It is then fine to not continue the exchange as long as you have clearly responded to any questions.
- In-person, never "follow" someone when they reverse anything you mirrored. Pause your mirroring until the conversation has moved on.
- In-person, avoid excessive mirroring, as it is better to seem cold yet attentive than to be discovered and risk being perceived as manipulative.