Why Does My Child Have to Move Their Whole Body Just to Move One Part?
Understanding primitive reflexes and body separation (the ability to move or stabilise one part of the body independently from another) matters for a child’s development.
When assessing children at our clinic, which specialises in child brain development, I often detect things parents often haven't noticed before. For instance:
I ask the child to move their eyes to follow an object and their whole head moves.
I ask them to turn their head and their shoulders and trunk turn with it.
I ask them to reach across their body and their entire body reorganises itself in order for them to do it.
I ask them to move one arm or one leg independently and everything else wants to join in.
It can look like clumsiness, poor coordination, fidgeting or simply a child who doesn't quite have control of their body. But developmentally, I am looking at something more fundamental:
Can this child move one part of their body without the rest of their body having to follow?
This ability to separate movements is an incredibly important part of development. Early in life, a child’s movements aren’t sophisticated.
A baby's nervous system relies heavily on automatic movement patterns, including primitive reflexes. These reflexes are normal and important during early development.
For example, with the Asymmetrical Tonic Neck Reflex (ATNR), turning a baby's head can influence the position of their arms and legs.
The important point is that:
HEAD MOVEMENT → automatically influences BODY MOVEMENT.
The baby doesn't yet have the mature voluntary control to say:
"I'm going to turn my head, but keep my shoulders, hands and trunk exactly where they are."
That comes later.
As development progresses, voluntary motor control becomes increasingly sophisticated. The child develops greater stability with their posture and learns to control the head, trunk, arms, hands and eventually the eyes with increasing independence.
We move from:
WHOLE-BODY MOVEMENT
to
SEPARATED MOVEMENT
and ultimately to
COORDINATED, INTEGRATED MOVEMENT.
Why do primitive reflexes matter?
Primitive reflexes are expected during infancy and normally become less dominant as voluntary movement and postural control develop.
In some children I assess, however, these early reflex patterns can still be elicited beyond the age at which we would usually expect them to be prominent.
This doesn't mean that a retained reflex is necessarily the cause of a child's difficulties. Research into retained primitive reflexes and developmental difficulties is still evolving, and intervention evidence is limited.
But clinically, they can provide useful information about how a child is organising movement.
For example, if I test ATNR and turning the child's head produces significant movement through the arm, shoulder or trunk, I become interested in something very practical:
How easily can this child turn their head without their body having to reorganise?
Because everyday life requires that ability constantly. Their head needs to become independent from the body
Imagine a child sitting at their desk. The teacher is speaking at the front of the classroom. The child needs to:
turn their head towards the teacher → listen → look back at the board → look down at their book → move their hand → write → look back up again.
Their head, eyes, trunk and hands are all doing different jobs. The trunk needs to provide a relatively stable base. The head needs to move independently on top of it. The arms and hands need to remain available for writing. And the eyes need to move within the head. That is a remarkably sophisticated neurological task.
If moving the head still causes a large amount of movement elsewhere in the body, these everyday tasks may require much more effort. Then the eyes need to become independent from the head
This is another pattern I see frequently in the clinic. I hold an object in front of a child and ask them to follow it with their eyes. I move it to the right. Instead of:
EYES → RIGHT
I see:
EYES + HEAD + SHOULDERS + BODY → RIGHT.
The child hasn't yet developed efficient eye-head dissociation for that task. That matters because we don't read by moving our entire head across every word.
Our eyes need to scan independently; they need to move:
LEFT ↔ RIGHT
UP ↕ DOWN
DIAGONALLY
and they need to converge together when looking at something close.
All while the head remains relatively stable when the task requires it. For children who move their whole head every time their eyes need to move, reading, copying, catching, navigating the environment and maintaining visual attention can potentially be much more demanding.
Importantly, persistent difficulty tracking with the eyes independently, or an eye that turns inward or outward, also deserves assessment by an appropriate eye-care professional such as a paediatric ophthalmologist or orthoptist. It shouldn't simply be attributed to primitive reflexes.
Think of development as learning to separate the body
I often explain the developmental progression to parents like this:
WHOLE BODY MOVES TOGETHER↓HEAD SEPARATES FROM BODY↓TRUNK BECOMES MORE STABLE↓ARMS AND LEGS MOVE MORE INDEPENDENTLY↓LEFT AND RIGHT SIDES COORDINATE↓EYES MOVE INDEPENDENTLY FROM HEAD↓THE SYSTEMS WORK TOGETHER WHEN NEEDED
The ultimate goal isn't actually independence.
It's integration.
We want the brain to be able to separate movements when necessary and then bring them together deliberately when a task requires it.
Think about catching a ball.
Your eyes track the ball.
Your head adjusts.
Your trunk stabilises.
Your arms move towards it.
Your hands prepare to catch.
Your balance system keeps you upright.
All of those systems are separate — but they cooperate beautifully.
That is integrated movement.
Why crawling is such an interesting developmental stage
This is one reason I pay attention to crawling history when assessing a child.
Crawling places fascinating demands on the developing nervous system. The child has to support their trunk while moving individual limbs. The left arm and right leg work together. Then the right arm and left leg. The head moves while the body remains supported. Weight shifts from side to side. The shoulders, pelvis and trunk have to coordinate. The eyes are beginning to interact with movement and the environment.
Crawling doesn't magically "fix" the brain, and missing crawling doesn't mean a child will necessarily develop problems.
But it is a wonderful example of the transition from large, automatic whole-body patterns towards increasingly controlled, cross-body movement.
What can this look like in an older child?
A child who finds movement separation difficult may appear to have a collection of completely unrelated challenges.
Parents might notice:
their whole head moves when they try to follow something with their eyes
their body turns when their head turns
they find crossing the midline awkward
handwriting looks effortful
sitting still at a desk is difficult
they lean, slump or constantly reposition themselves
catching and throwing are challenging
they struggle with coordinated sports
they use excessive movement to complete relatively simple tasks
or they appear much more coordinated when they can use their whole body than when asked to isolate one movement.
These signs can have many causes, so they shouldn't be used to diagnose a retained reflex by themselves. But together they can tell us something valuable:
look underneath the skill and ask how the body is organising itself to produce it.
This changes the question I ask about a child Instead of immediately asking:
"Why can't this child concentrate?"
I might first ask:
"How much effort are they using just to hold their body still?"
Instead of:
"Why is handwriting so difficult?"
I might ask:
"Can the shoulder, elbow, wrist and fingers move independently while the trunk remains stable?"
Instead of:
"Why won't their eyes follow the object?"
I ask:
"Can their eyes move without their head having to move too?"
And instead of:
"Why are they so clumsy?"
I might ask:
"Can different parts of their body perform different jobs at the same time?"
Those questions take us further down into the foundations of development.
This is why I build from the bottom up
At my clinic, I don't only look at the symptoms a parent brings through the door.
A child may come because of attention, handwriting, coordination, sensory seeking, emotional regulation, communication or learning.
But I want to know what is happening underneath those skills.
Within my Six Phases of Brain Development framework, I think about development progressing through:
Survival → Regulation → Awakening → Engagement → Integration → Expansion.
For a child who still relies heavily on whole-body movement, much of our initial work may sit within the earlier foundations: regulation, body awareness, postural control, balance and increasingly independent movement.
Only then do we ask those systems to work together during more complicated activities.
This is why a brain development programme may include apparently simple things such as crawling, all-fours activities, pushing and pulling, balance work, controlled head movements, cross-body activities and carefully selected visual tasks.
We're not doing simple exercises because the child's difficulties are simple. We're looking at whether we can make the foundations underneath the complicated skill more efficient. From one unit to many parts, and then back to one. This is perhaps the easiest way to understand what I am looking for.
Early development begins with a body that often responds in large, automatic patterns.
Development gradually gives the child greater choice:
I can move my eyes without moving my head.
I can move my head without turning my whole body.
I can reach with my right hand while stabilising myself with my left.
I can move one leg while keeping my trunk stable.
I can look at the teacher while my hands remain on my work.
And eventually:
I can bring all of those separate systems together to achieve something complicated.
That might be handwriting.
Reading.
Riding a bicycle.
Catching a football.
Getting dressed.
Sitting in a classroom.
Or playing with another child.
Development isn't simply about getting a child to perform a skill.
It is about building enough organisation underneath that skill that the child can perform it efficiently.
And sometimes, when we look beneath the obvious symptom, we discover that a child who appears to have difficulty with a higher-level skill is still working incredibly hard on something much more fundamental: learning how to control the different parts of their body independently, and then bring them back together when they need them.
