The symmetric tonic neck reflex (STNR) is a primitive reflex that appears in babies around 6 to 9 months old and helps them transition from lying on their stomachs to getting up on their hands and knees. It’s often called the “crawling reflex” because it lays the groundwork for crawling, and it normally disappears between 9 and 12 months as the brain matures. When this reflex doesn’t fade on schedule, it can cause a range of physical and learning difficulties that sometimes persist into school age.
How the STNR Works
The STNR links head position to limb movement in a predictable pattern. When a baby bends their head forward (chin toward chest), their arms bend and their legs straighten. When the baby lifts their head up and back, the opposite happens: the arms straighten and the legs bend. You can think of it like a seesaw between the upper and lower body, controlled by neck position.
This automatic pairing of movements gives babies a way to push up off the ground and rock back and forth on their hands and knees. It’s a critical stepping stone, not just for crawling but also for developing posture, hand-eye coordination, and the ability to coordinate both sides of the body at once. Once the brain has used this reflex to build those foundational motor skills, it integrates the pattern, meaning the child can move their head, arms, and legs independently of one another.
Why It Matters for Crawling and Beyond
Before the STNR appears, babies can’t easily break the connection between their upper and lower body to get into a hands-and-knees position. The reflex essentially teaches the brain that the upper body and lower body can do different things at the same time. Once a baby masters this, they begin crawling, and that crawling phase itself trains coordination, depth perception, and the ability to shift visual focus between objects at different distances.
The skills built during this window carry forward into childhood. Posture control, the ability to track a moving ball, copying text from a whiteboard to a notebook, and even swimming all rely on the independent head-and-limb control that develops as the STNR integrates.
Signs the Reflex Hasn’t Integrated
When the STNR remains active past 12 months, it continues to link head movement to limb position in ways that interfere with daily life. A retained STNR is characterized by poor posture, poor hand-eye coordination, and difficulty focusing. These signs often become most obvious once a child enters school and faces tasks that demand sitting still, reading, and writing.
Common indicators in school-age children include:
- Slouching or slumping at a desk. Because looking down at a paper triggers arm bending and leg straightening, the child’s body constantly fights to hold a seated position. Some children compensate by sitting in a W position on the floor.
- Difficulty sitting still. The reflex creates a tug-of-war between head position and limb tone, making it genuinely uncomfortable to stay in one posture for long.
- Trouble with ball games and swimming. Both activities require the head, arms, and legs to move independently, which is exactly what a retained STNR disrupts.
- Problems copying from a board. Shifting the eyes between a distant board and a close notebook demands the kind of vertical eye movement and rapid refocusing that a retained STNR can compromise.
Effects on Vision and Focus
One of the less obvious consequences of a retained STNR involves the eyes. Because the reflex ties head position to body tension, it also affects the stability of vertical eye movements and the ability to shift focus quickly between near and far distances. Children with an active STNR may struggle with reading fluency, lose their place when looking up and down between a board and a page, or have difficulty tracking objects that move vertically. These visual challenges are often mistaken for attention problems or learning disabilities when the underlying issue is neuromuscular.
Connection to ADHD Symptoms
A growing body of research has examined the overlap between retained primitive reflexes and attention difficulties. A 2023 meta-analysis published in Brain Sciences, pooling data from 229 children, found a moderate positive correlation between ADHD symptoms and a retained STNR (r = 0.39). A retained asymmetric tonic neck reflex showed an even stronger correlation (r = 0.48). This doesn’t mean a retained reflex causes ADHD, but it suggests the two are closely related. Some of the hallmark behaviors of ADHD in a classroom, such as fidgeting, poor posture, and difficulty sustaining attention on written work, overlap significantly with the physical effects of a retained STNR.
How It’s Assessed
Occupational therapists and developmental specialists typically check for a retained STNR by placing a child on their hands and knees and asking them to look up and then down. In a child whose reflex has integrated, the arms and legs stay stable regardless of head position. In a child with a retained STNR, looking down causes the arms to collapse while the legs push straight, and looking up causes the arms to lock while the legs fold. The more pronounced the movement, the more active the reflex.
Some clinicians use variations of this test, including having the child hold specific positions while moving the head, to make the reflex easier to detect. The hands-and-knees position is generally considered the most reliable way to reveal the pattern.
Integration Exercises
The goal of therapy is to help the brain finish the integration process it was supposed to complete in infancy. This involves repetitive, rhythmic movements that mimic the original reflex pattern and gradually teach the nervous system to decouple head position from limb movement.
One of the most common exercises is a slow, controlled cat-cow stretch: the child gets on hands and knees, arches the back while tucking the chin, then drops the belly while lifting the head. This deliberately activates the STNR pattern in a controlled way. Over weeks of consistent practice, the brain learns to override the automatic response. Variations include holding the arched or extended position (sometimes called a “frozen cat”) and adding cross-body crawling movements while in the hands-and-knees position.
These exercises are simple enough to do at home, but they work best when guided by an occupational therapist who can confirm the reflex is actually retained and track progress over time. Most integration programs involve daily practice for several months, and children often show improvements in posture, attention, and coordination well before the reflex fully resolves.