startle reflex
Noun: A normal, involuntary physiological response observed primarily in young infants, where a sudden, unexpected stimulus (most commonly a loud noise) triggers a distinct pattern of movement. The classic response involves the infant stretching out the arms and flexing the legs, often accompanied by a crying reaction.
This term is used specifically in medical, psychological, and developmental contexts to describe a primitive reflex. It is a key indicator of normal neurological function in newborns and young babies. - The "startle reflex" is also commonly known by other clinical names. - It typically diminishes and integrates as the infant's nervous system matures.
- The pediatrician tested the newborn's startle reflex by making a gentle, sudden sound near the bassinet.
- A persistent or asymmetrical startle reflex beyond a certain age may warrant further neurological evaluation.
- Parents often notice the startle reflex when their sleeping baby jerks awake after a door slams.
- Hyperexplexia: This is a pathological, exaggerated form of the startle reflex, which is a rare neurological disorder.
- Moro reflex: This is the primary clinical synonym for the startle reflex in infant medicine.
- Moro reflex (n): The standard medical term for the startle reflex in infants.
- Startle response (n): A more general term that can apply to the involuntary reaction to sudden stimuli in individuals of any age, though it differs from the specific infant reflex pattern.
- Startle reaction (n): Similar to "startle response," denoting the general reaction.
- Moro reflex
- Embrace reflex (a less common synonym referencing the arm movement)
While "startle reflex" precisely denotes the infant-specific reflex, the related term "startle response" has a broader application. The startle response refers to the general, rapid, involuntary reaction (often a jump or flinch) to a sudden stimulus, which is seen in humans and animals throughout life. The infant's startle reflex (Moro reflex) is a specific, patterned subtype of a startle response.
- a normal reflex of young infants; a sudden loud noise causes the child to stretch out the arms and flex the legs