Although most of us like to think of ourselves as rational decision makers, ample research shows that emotions play an outsized role in negotiations. If you can’t read what your counterpart is feeling and instead focus only on what he or she is saying, you’re highly unlikely to achieve everything you could have.

Of course, experienced negotiators know how to mask their true feelings. They choose their words, tone, body language, and expressions carefully. To the average observer, they often appear neutral, impassive. Or they’re able to convincingly fake an emotion if they think it will help them advance their own interests.

However, there is a way to read what your counterpart is feeling even if they are deliberately trying to hide it from you. The secret is to pay attention to the spontaneous and involuntary microexpressions that rapidly flit across everyone’s faces at times of intense emotion. If you know what to look for, they can provide an instant, honest window into how your counterpart is feeling.

Here are some examples of common microexpressions (as depicted by Patryk Wezowski — my husband and business partner — and me):

Photos courtesy of the Center For Body Language.

As you can see, it’s quite easy to recognize the meaning behind the expression on a still photo. In a real-life situation, however, when the stakes are high and the microexpression lasts for as little as one 25th of a second, it’s a different game entirely.

In my work as a body language researcher and instructor, I’ve long theorized that one of the key differences between exceptional negotiators or salespeople and those who are merely average is the ability to read these microexpressions, gauge visceral reactions to ideas or proposals, then strategically steer them toward a preferred outcome.

To test this idea, we conducted two experiments using videos like this one, which gauge users’ ability to recognize these expressions.

In the first study, we compared the video test scores of salespeople from the Karnak Stationery Company with their performance and found that those with above average scores noticeably outsold their colleagues. The second experiment involved salespeople from a BMW showroom in Rome, Italy. We found that high performers (who had sold more than 60 automobiles in the most recent quarter) scored almost twice as high on the test as low performers. Our conclusion: Effective negotiators seem to be naturally good readers of microexpressions.

The good news is this isn’t an ability you either have or you don’t. You can learn it, and get better at it over time, with practices tests and in real-life negotiations by following some simple rules:

Focus on the face. The next time you ask an important question in a negotiation, focus on your counterpart’s face for at least four seconds, instead of just listening to the words coming out of his or her mouth.

The next time you ask an important question in a negotiation, focus on your counterpart’s face for at least four seconds, instead of just listening to the words coming out of his or her mouth. Tell a story. Negotiators have an easier time controlling their expressions when they’re talking. So don’t ask too many open questions. Instead describe what you want or share an anecdote about another negotiating partner who shared concerns similar to theirs and watch how they respond as they listen. Their guard will lower a little and you’ll be able to see their honest reactions to what you’re saying — knowledge to guide the rest of the conversation.

Negotiators have an easier time controlling their expressions when they’re talking. So don’t ask too many open questions. Instead describe what you want or share an anecdote about another negotiating partner who shared concerns similar to theirs and watch how they respond as they listen. Their guard will lower a little and you’ll be able to see their honest reactions to what you’re saying — knowledge to guide the rest of the conversation. Present multiple options. As you present a list of choices to negotiating partners, their microexpressions will reveal which they like and which they don’t, sometimes even before they’re consciously aware of their preferences. Watch closely to see what their face tells you about each option.

Here’s how it might work in practice:

Imagine you’re a consultant who has proposed a certain fee for your services: “Based on your requirements, we can propose $100,000 as the consultancy fee for this project.” If you see your potential client show the microexpression of disgust, you can calibrate accordingly and lower your price without skipping a beat: “But because we anticipate a longer term collaboration and are excited about the direction your business is heading in, we can offer you 25% discount.”

What if you instead recognized an expression of happiness or contempt after the initial offer? Maybe your counterpart expected a higher price, or doubts that you’re offering the premium level of service. You could quickly adjust your price in the opposite direction: “That’s the basic fee which covers X and Y. For your project I also recommend our entire suite of services including A, B and C, which means the total price would be closer to $150,000.”

Attention to microexpressions allows you to secretly respond to the feedback your negotiating partners don’t even realize they’re giving, ensuring that you stay in control of the dialogue and achieve better outcomes.