Cardiovascular Reactivity
The degree to which heart rate, blood pressure, and stress hormones spike in response to a stressor—here, heightened in lonely people during social judgment situations.
The magnitude of physiological change in heart rate, blood pressure, cortisol, and other stress markers in response to a challenging or threatening stimulus. Greater reactivity means the body mounts a larger stress response; in lonely individuals, this is often pronounced during social evaluation or judgment scenarios.
What this means in real life
When a shy student is called on in class, their heart races and palms sweat more intensely than a confident peer's would—that exaggerated physical response is cardiovascular reactivity in action.
What it isn’t
It is not simply having anxiety or nervousness. Someone can feel calm mentally yet still show high physiological reactivity (racing heart, elevated cortisol) that they're not consciously aware of.
Commonly misused online
Often conflated with 'being emotional' or 'overreacting.' In reality, it's a measurable bodily response independent of how someone feels or behaves outwardly.