The Physiological Lens on Emotional Intelligence

An emotion is not complete until the body expresses it. Well, that's what it feels like sometimes. 

Think about the times that you were bursting with excitement. How hard would it have been for you to stop smiling? Or when you finally remembered the song name that you were haphazardly humming all day. That sigh of relief was almost instant, but necessary because it represented how you truly felt. 

Have you ever wondered about how that happens? How does your body express the emotion you're feeling without you consciously telling it to? 

Well, it is linked to research on our Nervous System. Our nervous system translates feeling into muscle tone, breath rhythm, facial movement, and vocal quality. It works almost like a processing plant, using prior expressions of emotion to turn internal feelings into behavioural outputs.

We often talk about emotions as though they live purely in the mind: thoughts we can analyse, label, or manage through willpower alone. But neuroscience tells a different story. The moment we experience joy, irritation, anxiety, or pride, our autonomic nervous system shifts. Heart rate changes. Breathing adjusts. Muscles tighten or soften. Hormones are released. Before we consciously decide how to respond, the body is already moving.

This is why happiness becomes a smile rather than just a pleasant thought. The parasympathetic branch of the nervous system promotes relaxation in the face and warmth in the eyes. Vocal tone softens. Posture opens. Likewise, with anger, the feeling sometimes has an involuntary outburst. A form of physiological mobilisation where adrenaline rises, breath sharpens, the jaw tightens, and the voice gains volume. The body prepares for action, and others can see and hear it immediately.

Researchers used to think that emotions came before emotional expression. But more modern thinkers like neuroscientist Lisa Feldman Barrett explain how the brain is continuously integrating bodily signals to construct what we experience as ‘emotions’. In other words, emotions are not hidden internal events, but rather embodied processes that ripple outward.

The Science of it All

I’m sure we all know a person whose facial expression speaks before they do. You can always visibly tell what mood they are in, even without them saying a word. 

Most times it's unconscious, as our bodies are simply drawing on past expressions of an emotion. An explanation of this can be found in research on the Vagus Nerve. It is known as the 10th cranial nerve and is the longest nerve in the body, running from the brainstem all the way down to the colon. The vagus nerve plays a crucial role in regulating many bodily functions, including digestion, heart rate, breathing, and immune function. It is a major component of the parasympathetic nervous system, which is responsible for the body's ‘rest and digest’ response, as opposed to the ‘fight or flight’ response of the sympathetic nervous system.

Activation of the vagus nerve can promote relaxation, decrease heart rate, increase digestion and nutrient absorption, and improve immune function. Dysfunction or damage to the vagus nerve can lead to a variety of symptoms, including immune system dysfunction.

Research from Stephen Porges and The Polyvagal Theory shows that our vagus nerve directly influences: Facial muscles, vocal tone, heart rate, and breathing rhythm. So emotion literally shapes:

• The muscles around your mouth (smile)

• The tension in your jaw (anger)

• The pitch of your voice

• The speed of your speech

Through emotional expression, our nervous system becomes visible. 

Where Emotion Becomes Experience

Even though research favours the origin of our emotional expression within our nervous system. Emotion is not a straight line from brain to behaviour. It is rather seen as a loop. One that is dynamic, fast, adaptable, and continuous.

For decades, emotions were described as reactions triggered by specific brain regions. But contemporary research paints a more complex picture. Lisa Feldman Barrett proposes that the brain is constantly predicting and regulating the body in anticipation of what we might need next. This process, known as allostasis, ensures that our internal systems are prepared for action before we are even consciously aware of a feeling.

Imagine you are about to speak in a meeting. Before you are conscious of any feelings, your heart rate may already have increased. Your breathing may have shortened. Muscles in your shoulders may have tightened. The brain has predicted that you may be feeling nervous, based on prior experiences, and adjusted your physiology accordingly.

But the loop does not stop there.

Your body continuously sends signals back to the brain through interoceptive pathways, via the vagus nerve, spinal cord, and hormonal systems. The brain interprets these signals in context. For example, a racing heart at a finish line may be experienced as exhilaration,, but the same sensation in a boardroom may be seen as anxiety. Whilst the bodily data is similar, the interpretation of the data is different. 

Interoceptive awareness helps interpret bodily sensations as emotions. Emotion, then, emerges from the integration of prediction, bodily sensation, memory and environment.

The feedback loop deepens further when expression enters the picture. Facial muscles, vocal tone, posture, and breath do not just communicate emotion outward; they reinforce it internally. Research on facial feedback, including work by Paul Ekman, suggests that holding certain expressions can intensify or soften emotional states. A tightened jaw sustains tension. A softened gaze can reduce it.

And because our nervous systems are socially responsive, our expressions influence the physiology of others. A calm tone can regulate a room. A sharp voice can mobilise it.

Emotion, therefore, is not just something we feel. It is energy that is flowing from one person to another, influencing and persuading with every smile, nod, or shake of the head. This knowledge flows alongside the concept that at least 60% of our communication is non-verbal. It is in the facial expressions and body language that we can truly see how each other feels. 

Why This Matters for Teams

Emotional intelligence in teams is not just the ability to label feelings. It is the capacity to recognise how our physiology shapes the room and how to regulate ourselves in ways that create safety.

If emotion is a brain–body feedback loop, then emotional intelligence training in teams may not just be about awareness or empathy. But rather about physiology in motion. This is about examining our responses and reactions, ensuring that they align with the values and cultural expression of the organisation. 

Teams are not just groups of minds; they are networks of nervous systems constantly influencing one another. The tone of a colleague's voice, the tension in their posture, and the pace at which they speak are all cues left to be felt by others. When a team member enters a meeting visibly tense, speaking sharply, and breathing shallowly, others’ nervous systems respond. Heart rates rise. Defensiveness increases. Cognitive flexibility narrows. Conversely, regulated breathing, steady tone, and open posture promote psychological safety, enabling clearer thinking and more collaborative problem-solving.

This has profound implications for performance. Under stress, the prefrontal cortex, responsible for reasoning, perspective-taking, and impulse control, becomes less effective. Reactivity increases. Listening decreases. Therefore, leaving us to hypothesize that teams under chronic physiological strain do not lack intelligence; they lack regulation. The strength of emotional intelligence, then, in this context, is the ability to self-regulate. Leaders shape company culture and staff behaviour through their own regulation. In practice, this means emotional intelligence is contagious. One regulated nervous system can stabilise a room. One dysregulated response can unsettle it.

Understanding this moves Emotional Intelligence Training beyond soft skills. It becomes a core leadership competency, one that directly influences collective performance.

Understanding the physiological lens of emotional intelligence changes how we approach behaviour in teams. It moves us away from judgment and towards awareness. A raised voice is not simply poor communication; it may be sympathetic activation. Withdrawal may not be disengagement, but shutdown. A calm presence may be more than composure, it may be an act of regulation that stabilises an entire group.

The question is no longer, ‘How do we control our emotions?’ but ‘How do we understand and regulate the physiological signals that shape how we lead and work together?’

At The EQi Glow, we work directly with teams to translate this science into practical skills. Our training programmes help leaders and employees:

• Recognise early physiological signs of stress and escalation

• Develop regulation strategies that improve clarity under pressure

• Communicate in ways that build psychological safety

• Build emotionally intelligent cultures rooted in awareness, not reactivity

If you are ready to move emotional intelligence beyond theory and into embodied, everyday practice, we would love to partner with you. Send us a message now on hello@eqiglow.uk for your custom quote for this experience. 

Image gotten from https://www.morningsideacupuncturenyc.com/