Here’s the thing about human nature: I know why I’m scowling (I’ve got a headache), and when I see my friend scowl, I realize it’s unusual (she’s having a bad day), but I will likely assume it’s part of his basic character (he’s an insensitive pig) when I see the same negative expression on someone I dislike or don’t know well.

Everyone evaluates body language in this manner. And it’s why your nonverbal signals don’t always convey what you intend them to.

But it’s not the only reason. In fact, there are five common mistakes people make when they read your body language.

1.) They don’t consider the context. When it comes to body language, context is king. You can’t really make sense of someone’s nonverbal message unless you understand the circumstances behind it. Context is a weave of variables including location, relationships, time of day, past experience, and even room temperature. Depending on the context, the same nonverbal signals can take on totally different meanings.

Your team members and colleagues don’t always have access to this insight. So if you yawn in a staff meeting because you were up early for an international business call – let people know why you’re tired. Without this context, you’ll look like you’re just bored.

2.) They find meaning in one gesture. People are constantly trying to evaluate your state of mind by monitoring your body language. But all too often they will assign meaning to a single (and sometimes irrelevant) nonverbal cue. And, since the human brain pays more attention to negative messages than it does to positive ones, people are mainly on the alert for any sign that indicates you’re in a bad mood and not to be approached. So – you may be more comfortable standing with your arms folded across your chest (or you may be cold), but don’t be surprised when others judge that gesture as resistant and unapproachable.

3.) They may not know your baseline. One of the keys to accurately reading body language is to compare someone’s current nonverbal response to their baseline, or normal behaviour. But if people haven’t observed you over time, they have little basis for that comparison. Remember this when meeting people for the first time. They won’t know that you habitually frown when you are concentrating. (And you may not realize it either unless you ask a friend or coach for feedback.) Others will most likely think the frown is a reaction to something they said or did.

4.) They evaluate you through an array of personal biases. There is a woman in my yoga class who liked me from the moment we met. I’d prefer to believe that this was a result of my charismatic personality, but I know for a fact that it’s because I resemble her favourite aunt. Sometimes biases work in your favour – an example of the so-called “halo effect.” But biases can also work against you. What if, instead of someone they like, you remind people of someone they despise? You might overcome it with time, but you can bet that their initial response to you won’t be a good one.

5.) They evaluate you through a filter of cultural biases. When it comes to nonverbal communication and cultural differences, you can expect to be judged by behaviours that include how close you stand to a colleague in conversation, how much or little you touch others, the degree of emotion in your voice, the amount of eye contact you display, and the kind of hand gestures you use. And what feels so right in one culture may be seen as highly insulting in another. (So before you attend that international business meeting, do a little research to on the nonverbal business practices that you’re most likely to encounter.)

These are the five mistakes people make. Understanding them – and trying not to make the same errors – can give you a nonverbal advantage. Start by giving others the benefit of a doubt. Maybe they just have a headache.

Carol Kinsey Goman, Ph.D. is an executive coach, change-management consultant, and international keynote speaker at corporate, government, and association events. Her column is distributed through Troy Media.