The startle reflex is an automatic response to sudden or unexpected stimuli, such as loud noises or quick movements. This reflex is a protective mechanism that prepares the body to react to potential threats. It involves a rapid contraction of muscles, often resulting in a jump or flinch. This reflex is particularly strong in infants and can be observed in many animals, including cats and dogs. The startle reflex is part of the body's fight-or-flight response, which helps individuals respond quickly to danger. It is a fundamental aspect of human and animal behavior, aiding in survival.