We've all had to deal with passive aggressiveness at some point. A boss raises a dismissive eyebrow when you speak, or a friend boxes you out of the conversation at a group brunch.

But the lines are often blurred. I certainly struggled with this myself, which is why I spent much of my time at Harvard researching body language and communication.

I always recommend taking the high road, rather than firing back or being hostile. Here are three signs of passive aggressive or childish behavior, and how to respond effectively:

1. Extreme brevity

You send your boss an email asking, "Should we go ahead and schedule a meeting with this potential client?" — and they reply with a curt, one-word answer like "yes," "fine" or "OK."

Some people simply prefer to give short, to-the-point answers. But if you notice that they're mostly responding this way to you, and not to others, then this level of brevity might be an indication of passive aggressiveness.

How to respond:

• Ask clarifying questions: "Thanks! What day and time works best for you?" or "Is there anyone else I should invite?"
• Keep your cool: Don't take the bait. Stay focused in the present and avoid acting defensively.
• Use humor: Humor is a great way to diffuse tension. You could say, "If we don't land them as a client, at least we got a free meal on the company!"
• Gently address it: This can be helpful in some cases. The goal is to show genuine intent and a desire to understand: "I feel you might be upset with me. Is this right?"

2. Slow responses

Getting the silent treatment can show up as delayed emails or texts, or even ghosting behavior.

Being on the receiving end of these actions can trigger what I call "timing anxiety," an intense worry we feel when we find ourselves wondering about all the possible meanings behind the slow responses.

Unfortunately, there are no hard-and-fast rules to know for sure if someone is using silence as a deliberate slight, or if it is just an oversight.

How to respond:

• Don't jump to conclusions. Unless it's critical that you get a reply ASAP, remember that you never really know what someone is going through. Maybe they have a lot on their plate, or are dealing with personal issues.
• Send a gentle reminder: Some people genuinely forget, so a follow-up can be helpful: "When you get a chance, I'd love to chat about this."
• Switch to a different mode of communication: If you follow up twice with no response, try sending a work DM instead of an email. Or swing by their office if they aren't answering their phone.

3. Change from informal to formal language

If you're texting and emailing with someone and they change their tone from informal to formal out of nowhere, it might mean they are trying to assert power.

A similar situation might be a friend who is suddenly very cold or detached in their language over text. For example, going from "Yea, that sounds like fun!" to "Sure, whatever."

How to respond:

• Don't automatically assume they're angry with you: It's easy to jump to the conclusion that you are being singled out, but that's often not the case. In fact, their behavior may have nothing to do with you.
• Reach out by phone, video chat, or in person: It can be hard to decipher how someone really feels through digital communication. Reach out in a more personable way and explain the source of your anxiety. Don't be apologetic or accusatory. Just be honest and ask for clarification. This will help you build trust and connection, no matter the distance.

Erica Dhawan is a Harvard-trained researcher, keynote speaker and author of "Digital Body Language: How to Build Trust and Connection, No Matter the Distance." She is also the founder and CEO of Cotential, a company that has helped leaders and teams leverage collaboration skills. Follow Erica on Twitter @ericadhawan.

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