Giving feedback may be one of the most difficult challenges a manager faces. On the one hand, you have to be honest; on the other hand, you don't want to alienate your employee. You tread a fine line between maintaining cordiality and successfully getting your point across.

A positive workplace culture is essential for employee engagement and productivity. Empathy at work creates psychological safety, which research by Amy Edmondson of Harvard demonstrates, is created when managers are inclusive and humble and encourage their staff to speak up or ask for help. Psychological safety improves learning and performance outcomes. More important, feeling safe in the workplace helps encourage the spirit of experimentation that’s so critical for innovation.

By using this kind of positive, open, and supportive feedback style, you end up establishing trust. Employees are especially sensitive to signs of trust in their managers. Our brains respond more positively to empathic bosses, as neuroimaging research confirms. In turn, employees who feel greater trust show improved performance. Positive relationships at work can even lower health care costs by improving employee health: Having positive workplace relationships strengthens your immune system and lowers your heart rate and blood pressure. Leaders and managers in particular influence their employees' well-being more than they even know. A 3,000-person study found that a leader’s behavior and personality even influence their employees’ heart health. It’s no wonder that employees prefer higher happiness at work to higher pay — and that the happiness they seek is characterized by positive, supportive relationships.

Despite this need for a positive workplace culture, there is no doubt that giving critical feedback is essential. The question is how to deliver it. Most advice in this area focuses on what to say — for example, give more praise than criticism, and listen more than you talk. Those are important, but our nonverbal communication is just as important as the words we use.

Whether we realize it or not, we are constantly reading each others’ facial expressions and body language. Imagine that you are the person walking into someone’s office to receive feedback or that you are in an interview. By definition, your boss or the interviewer is in the position of power. You are probably paying close attention to their facial expression and nonverbal cues to get an idea of where they are coming from and how they are responding to you. Here are the nonverbal cues to which we pay the most attention: 

Facial expression. We deduce how someone is helping from their facial expression. Someone’s smile activates the smile muscles in your own face, while their frown activates your frown muscles, according to research by Ulf Dimberg. We internally register what another person is feeling by experiencing it in our own body. Smiling is so important to social interactions that we can discern whether someone is smiling even if we can’t see them. Your smile is thus something to think about even if you are delivering feedback over the phone. Smile appropriately to project warmth and goodwill.

Eye contact. Research shows eyes really are the windows to the soul: You can predictably tell someone’s emotions from their gaze. Eye contact is the crucial first step for resonance, a term psychologists use to describe a person’s ability to read someone else’s emotions. It’s also important for creating a feeling of connection. Make and maintain eye contact when you’re giving someone feedback.

Voice. From infancy, we are acutely aware of the voices of people we consider important, and the way we feel about another person shifts the way we speak. The tone of our voice, more than the words themselves, can give away how we feel. In fact, new research shows that we can often predict someone’s emotions from their voice.

Posture. The way a person is sitting — slumped or sitting tall, arms open or crossed — transmits a message. When we walk into a room and find someone sitting with their arms crossed, we feel less connected to them. Having your chest open, arms uncrossed, making sure to keep nodding, smiling, and vocalizing (saying things like “mhmm” and “yes” in response to the other party) will help. Make sure you take on a nondominant stance; after all, your role is already powerful. The best way for the other party to hear you is if you are not domineering.

Breath. Research shows that the emotions we feel change the way that we breathe. You have probably noticed that when you’re stressed or angry you breathe quickly and shallowly, and when tired or exasperated you are more likely to sigh. Similarly, when we are with someone who sighs a lot, we may feel that they are annoyed at us. Before the conversation, try to take some deep, calming breaths. When you exhale, your heart rate and blood pressure decrease, so focus on breathing out longer than you breathe in. Doing this for a couple of minutes before a meeting will help you start the meeting from a place of calm. That calmness will also help your interlocutor feel more at ease.

Attention. Our mind wanders 50% of the time, research suggests. Moreover, given our busy schedules and the messages and emails that are popping onto our screens throughout the day, we sometimes are not present with the people in front of us — we’re still processing something that happened earlier, or we’re thinking about an article we just read or a phone conversation we just had. And the people you are talking to can tell. Because you are not fully present, you are less likely to hear them and respond to them skillfully, let alone understand where they are coming from.

Despite all this advice, it’s critical that you be authentic, or your efforts will backfire. Just think of how you feel when you’re around someone who seems to be something they are not: We often walk away feeling uncomfortable or manipulated. Our blood pressure rises in the face of inauthenticity, according to research by James Gross at Stanford University.