Tag Archives: reflexes

BABY STARTLE REFLEX

EMERSON DEMONSTRATES THE STARTLE REFLEX

YouTube Preview Image

Reflexes, we learned in a recent post, are involuntary movements elicited by an outside stimulus.  In this video posted on youtube (mandkyeo’s Channel), the sound of Emerson’s mother blowing her nose triggers his startle reflex.  Emerson quickly flexes (bends) his elbows and shoulders, pulling his arms toward his body.  His eyes widen and he stiffens his back as he quickly moves his body backward, away from the loud sound.  Soon, he relaxes his eyes and face just before bursting out in laughter….only to be startled once again by that loud and scary sound coming from mommy’s nose!  The pattern repeats itself once again: startling followed by laughing.  This video gives us the chance to see the vulnerability of the startle position.  The arms are bent with fists clenched and held close to the torso as baby moves quickly and abruptly away from the sound.  The opposite of this would be moving toward the sound by reaching, leaning and stepping forward.  This would be a posture of interaction or confrontation with the threat.  This is one of a series of Stellar Caterpillar posts examining the reflexes evident in baby’s first year.


WHAT IS A BABY REFLEX ?

BABY REFLEX DEFINED

5 MAIN ATTRIBUTES OF INFANT REFLEXES:

  1. INVOLUNTARY MOVEMENTS
  2. TRIGGERED BY EXTERNAL STIMULUS
  3. AUTOMATIC, NOT “LEARNED”
  4. SURVIVAL OR PROTECTION IS OFTEN THE PURPOSE
  5. CONTINUOUS STRENGTH OF MOVEMENT

Reflexes are involuntary movements that are usually triggered by an external stimulus.  For example, a gentle scratching of baby’s foot with a sharp object results in a quick flexion of the hip, knee, and ankle to pull the foot away from danger.  Infants do not “learn” reflexes, they are automatically present for a specific length of time.  Many reflexes are present at birth, some at 3 or 4 months, and others at 6 or 7 months.  They disappear just as they appear–automatically–in a matter of a few months.  In some cases they remain present longer than the usual length of time.  The purpose of many early reflexes is often survival or protection.

Another important aspect of reflexes is that they cannot fatigue or habituate.  Fatigue means to tire to the point that they stop working, as muscles tiring in a workout demand you stop and rest.  To habituate is defined as a gradual decline in a response over time.  For example, a fetus may respond to a loud sound placed near the mother’s belly by strongly contracting the limbs, yet with repetition the reaction gradually lessens until it stops.  Since a reflex cannot fatigue or habituate it will continue to occur over and over again at the same strength if the trigger stimulus is presented.

INVOLUNTARY VS. VOLUNTARY MOVEMENTS

The Stellar Caterpillar blog will examine important reflexes visible during baby’s first year and explore their role in motor skill acquisition.  It is important for parents to learn when a movement is voluntary (a motor skill) versus involuntary (a reflex).  Another way to differentiate between these two kinds of movement is to understand that the voluntary/motor skill movements are the intention of the baby, while the involuntary/reflexive ones are not her intention but the automatic response of her brain and nervous system.  Sometimes a baby may be moving as a result of a reflex and the parents mistakenly think that’s what baby wants to do!  Clever parents will learn to encourage the development of intentional movements through reading Stellar Caterpillar tips.  Baby will then scoot, crawl and reach her way to the heavens!