What Is a Startle Response?


Ernst Moro identified certain neurological reflexes that developed in the womb, continued after birth and normally continued up to the third or fourth month of life. When this Moro reflex continues into childhood and adulthood, it is considered abnormal.


Infants respond to unexpected stimulus with widened eyes or a startled look, a sharp intake of breath and other body movement. This "primitive" response increases adrenaline flow, heart rate and blood pressure.


If this infantile primitive response to noise and light and sudden movement continues into childhood, it continues to affect the flow of adrenaline. With excess adrenaline and subsequent activity, the child is often called moody, oversensitive or hyperactive as a result.


Adults who retain the Moro reflex are hyper alert and hypersensitive to changes in their environment. The result may be withdrawal or hyperactivity.


The Moro reflex integrates with normal movement as the infant matures and becomes accustomed to its surroundings. Confined movement, injuries, drugs in breast milk, over-stimulation either physically or emotionally, threatening surroundings and media overload are among things that can inhibit this process. Startle response is also known as startle reflex, embrace reflex and Moro reflex. It is normal in infants, but not in children or adults.