What Are Primitive Reflexes?

What are primitive reflexes? Why do they matter? And what do they have to do with sensory processing? This article will address these and a few more questions you didn’t know you had about primitive reflexes.

You are probably most familiar with reflexes from being on the exam table, the doctor tapping your knee and then watching as your foot involuntarily kicks out. You aren’t consciously thinking that you should kick—it is a reaction that happens from the stimulus on your knee.

Baby survival mechanism

Primitive reflexes are involuntary movement patterns like that knee kick. They don’t need the cortex (higher level thinking center) of the brain to respond. Rather, these responses originate in the brain stem and prompt an automatic action.

Why do we have these movement patterns? At first glance these seem and look rather odd. These reflexes are actually critical for a baby’s survival. The ability to suck, grasp something that touches the palm, and the motions needed to pass through the birth canal are all from primitive reflexes. Primitive reflexes are like nervous system programs designed to help a baby do certain specific tasks needed early on. Later, some higher level brain functions will replace these lower level (brain stem) reflexes.

Babies, quite simply, don’t have the ability to cognitively map their way through the early stages of life. They aren’t able to think “turn this way to get out of the birth canal”. Primitive reflexes are amazing in that they are set movements that are stimulated by a sensation. The action that results doesn’t even need to get processed by the thinking brain. The result is quick. Just like when you touch a hot stove, you pull your hand back quickly without thinking, a primitive reflex is set for a quick protective action.

Babies need primitive reflexes to survive. These quick acting responses to stimulus help a baby get through an otherwise very helpless time. So what happens when they aren’t babies anymore? Do they still have these reflexes?

What happens to reflexes when a baby gets older?

First, let’s quickly talk a little about the brain. Brains deal in the currency of energy (glucose). And brains are greedy! Cool side fact-did you know that the brain uses approximately 20% of the calories you consume?¹ Some tasks and functions use more energy than others. The brain, being greedy like it is, will choose the actions that require less energy (glucose).

Primitive reflexes, being based in the lower area of the brain, use more energy. Higher level thinking (cortex) tasks require less energy. So as a baby, toddler, or even adult, creates higher level pathways that the brain becomes familiar with, the lower level reflexes are not used and thus, “disappear”.

So, did those automatic actions really disappear? No! Those programs are still there, unused. They can “come back” in times of stress, fear, injury or accident. If you are familiar with these patterns they can even be spotted in professional athletes! The moment of intense pressure of catching a football can elicit a primitive reflex even in the NFL.

Undoubtably, however, we want these primitive reflexes to stay unused once their usefulness has worn out. When the higher level areas of the brain are in control we give our bodies amazing abilities! We can write a note, ride a bicycle, and mow our lawn.

When does a baby no longer need a primitive reflex?

There are many different primitive reflexes. Each one has its own useful time period. Some are “done” being needed with the birth process and some are needed well into toddler hood. Each of these reflexes has a typical time range that it is considered useful and “normal”.

So what happens if the primitive reflex is still around after it shouldn’t be? These are known as retained primitive reflexes. Basically, it means that the brain is using more energy than it needs to and that reflex is likely to interfere with other higher level tasks that a body can learn. For instance, the Moro reflex can mean that when a child is frightened, the eyes and head tilt back and the arms can come out in a fright pattern. This is useful as a baby to prevent injury in falling, but it would interfere totally with someone who wants to become a cheerleader.

To give ourselves and our children the best opportunities in life, we want to help these primitive reflexes fade into the background. This allows our higher level brain functions to give us the complexity of movements that we need to thrive in life. We say that a primitive reflex is integrated when a common stimulus no longer illicits that pattern.

What do primitive reflexes have to do with sensory integration?

I know, I know. Why does a sensory processing disorder site like this have a post about primitive reflexes? Are primitive reflexes and sensory integration even related? Yes! Go back to what a primitive reflex is—an automatic movement pattern response to a sensory stimulus. Let’s use an example.

The palmar primitive reflex is a sensory stimulus (touch) that is applied to the palm and results in the hand closing around it. After a while, the hand lets go of the item. It is the holding on to something that allows the baby to learn about the sensation of touch. During this time the brain is accumulating a touch sensation file. The nervous system is laying down pathways in the higher centers about what it feels and what action it may need. Eventually, the higher pathways created are travelled often enough to become the “thoroughfare”. This is when the baby has tried a variety of textures that it recognizes as safe and the reflex is not activated as often.

At this time, the reflex is integrated and the higher level center allows for more complex movement of the hand to be developed. This allows the baby to go from a whole hand grasp to more distinguished moves like a finger pinch.

If sensory processing is a problem, the primitive reflex may remain active and will limit the fine motor skill development as well as additional sensory processing skills. Addressing the reflex will allow not only for higher motor functions but also improved sensory processing.

What should I do if my child has a retained reflex?

There are too many reflexes to get into the details of when each should be integrated in this blog post and what to do about each one, but there are some important things you should do if you are concerned about retained reflexes. First off, talk to your doctor and ask for an occupational therapy (OT) or physical therapy (PT) evaluation. Check to be sure that the therapist you will see has been trained in primitive reflexes.

At your appointment the therapist can perform tests to see if certain reflexes have been integrated or if they are retained and still present. Then, they can do and recommend good activities that will help your child integrate the reflex and enable them to activate that higher level brain for complex activities.