Everybody cites emotions for a wide scope of things, from regulating social life to sports performance, cognitive brilliance political success or academic failure. But do they really understand what they’re talking about?
Emotions can be viewed through the lens of how the brain processes internal and external signals. Interoception deals with our internal body signals, while exteroception refers to external sensory input: the events that occur in the environment and reach us through our senses. Is this duality enough to characterize emotion? Surely not! The dimensions of valence (positive vs. negative) and arousal (high vs. low) are also needed to complete the picture.
At their core, emotions are the brain’s way of interpreting and responding to what’s happening inside and outside the body. Interoception refers to our perception of internal states—like heartbeat, breathing, or gut sensations. Exteroception, on the other hand, covers the outside world—what we see, hear, or touch. Emotions likely emerge from the interplay of these two systems, filtered through the brain’s prediction machinery, such as the insula and prefrontal cortex, which integrate these signals and assign meaning.
Valence—whether an emotion feels positive or negative—depends on context and interpretation. Positive valence might arise from a ‘rewarding’ interoceptive signal, like a steady heartbeat after a satisfying meal, or an exteroceptive one, like hearing music we love. Negative valence could stem from a racing pulse (interoception) signaling anxiety, or a loud noise (exteroception) triggering fear. The brain doesn’t just passively receive these inputs; it actively predicts and evaluates them based on past experiences. For instance, a high heart rate might be interpreted as excitement during a demanding physical task, like playing sports, while a loud noise could be processed as pleasant, such as during a fireworks display.
Arousal, the intensity of an emotion, ties into the autonomic nervous system. High-arousal emotions—like excitement (positive) or panic (negative)—activate the sympathetic nervous system, speeding up breathing and heart rate, whether from internal cues (anticipating a big event) or external ones (a sudden scream). Low-arousal emotions—like contentment (positive) or sadness (negative)—shift toward parasympathetic dominance, slowing things down. Dopamine or adrenaline might spike in high-arousal states, while serotonin or oxytocin could prevail in calmer ones.
I’d like to emphasize that no emotion is purely interoceptive or exteroceptive—it’s a dance between the two. Joy might begin with an external trigger (a friend’s smile) but amplify through internal warmth or a dopamine surge. Fear might start with a racing heart (interoception) but take shape from what we see (a shadowy figure). Valence and arousal are the brain’s tools for tagging and prioritizing these signals to guide behavior: approach the good, avoid the bad.
Of course, there are ways to intentionally manipulate our emotions. We can tweak them by hacking these systems. Slow breathing can dial down high-arousal negatives (anxiety) via interoception, so that —even if the external situation has not changed— our body will be responding in a less tense manner, which will open a new set of possible behavioural outcomes. On the other side, shifting our attentional focus to a pleasant external stimulus—like nature—can nudge valence toward positive through exteroception. It’s all about understanding the levers our brain and body give us and being able to play them to some extent.
Unlocking the physiological secrets behind human behavior isn’t just a noble scientific quest—it’s a game-changing tactic to supercharge our everyday lives, helping us thrive, adapt, and find more joy in the process.