When we talk, sing, or dance, we often bob or tilt our heads to emphasize the messages we’re trying to convey. But how effective are these head movements when it comes to reading others’ emotions? According to a recent study published in the journal Emotion, our heads alone may accurately express our emotions, even without the help of sound or facial expressions.

Body language is a form of nonverbal communication — often subconscious — that uses our body movement and gestures to pass along information, according to the Encyclopedia of Communication Theory. There are thousands of possible signs that can be communicated through these movements, which influence our personal interactions in various environments. With body language, we can often convey a great deal of information without ever speaking, solely by using different parts of our bodies in different ways.

For the study, Steven R. Livingstone and Caroline Palmer, from McGill University’s Department of Psychology, examined how the emotions vocalists expressed influenced their head movement, and how their head movements were subsequently perceived. The researchers used motion-capture equipment to track the vocalists’ head movements in 3D while they spoke or sang with a variety of emotions. These were classified as very happy, happy, neutral, sad, and very sad. The video clips were then shown to viewers to see if they could accurately identify the emotions without hearing sound or seeing the facial expressions — only their head movements were visible.

“We found that when people talk, the ways in which they move their head reveal the emotions that they’re expressing,” Palmer said in a press release. “We also found that people are remarkably accurate at identifying a speaker's emotion, just by seeing their head movements.”

This study follows the researchers’ own impromptu study, which was held in a bar and involved their lab mates. While at a lively bar in Montreal, Livingstone recalled a friend of his started to talk to him excitedly, yet he couldn’t hear or see his the friend’s face. “Suddenly I realized it was the animated way that he was bobbing his head that told me what he was trying to say,” he said.

Livingstone took into consideration his friend’s high frequency of head movement, which implied he was in an excited or alerted state. Typically, high-frequency head movements show higher levels of arousal than low-frequency head movements. This translates into different types of emotion recognition, as it shows how excited or upset the person is.

Relying on head movements to identify emotional states, therefore, can help us decipher what someone is trying to convey in situations where sound is not available. Good to know next time you’re in a loud bar.

Source: Livingstone SR and Palmer C. Head Movements Encode Emotions During Speech and Song. Emotion. 2015.