Why do people get startled?

People get startled as a reflexive response to unexpected stimuli, which is rooted in the body's fight-or-flight mechanism. This instinctive reaction prepares an individual to respond to potential threats by triggering a surge of adrenaline, increasing heart rate, and heightening awareness. Startling can also be a social or psychological response, as it often reflects surprise or fear in reaction to sudden movements or loud noises. Overall, it serves as a protective mechanism to help humans react quickly to their environment.