Sensory processing
The STNR: The Reflex Behind the Crawling Story, and What the Evidence Says
The symmetric tonic neck reflex is one of the three most often found still active in school-age children. Here is what is actually known about it, including where the references go quiet.
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The symmetric tonic neck reflex — the STNR — links head position to what the arms and legs do: bending or extending the neck changes flexion and extension in the limbs. It is described as one of the brainstem-mediated automatisms that typically integrate during the first year of life.3 Two things make this page different from the others in the series. First, the standard clinical reference names the STNR without giving it an integration window at all, where it gives one for the Moro, the ATNR, the palmar grasp and the Galant.1 Second, it is one of the three reflexes most frequently found still active in school-age children, and therefore one of the most often cited in commercial programs.2 Both are worth knowing before weighing a recommendation built around it.
What is the STNR (symmetric tonic neck reflex)?
The symmetric tonic neck reflex ties head position to limb tone: flexing or extending the neck produces a corresponding change in flexion and extension in the arms and legs. Along with the ATNR and the TLR it is described as a brainstem-mediated automatism that, in typical development, integrates within the first year of life.3
The crawling story. The STNR is the reflex most often invoked in the claim that a child “skipped crawling” and that this matters later. Crawling is not a milestone every typically developing child passes through in the same way, and the reflex literature does not establish that skipping it causes later difficulty. What the evidence does say is set out below.
When does the STNR appear and integrate, and how does it relate to crawling?
The STNR is described as integrating within the first year,3 but the standard clinical reference gives it no appearance point or integration window,1 and crawling, the milestone it is usually tied to, is not on CDC’s milestone checklists at any age.6
This is unusual enough to state directly. The StatPearls primitive-reflex chapter gives an appearance point and an integration window for the Moro, the ATNR, the palmar grasp, the plantar grasp, the Galant, the stepping reflex and the Babinski. For the STNR it gives neither — the reflex is named as one of seven dimensions in an assessment scale, and that is all.1
That does not mean the STNR is not real or not worth assessing. It means that if a program is built around integrating it by a particular age, the age is not coming from the same place the Moro’s is.
On crawling. CDC’s checklists list the skills most children — 75 percent or more — can be expected to show by each age.7 From 2 months to 5 years, crawling is not one of them. It appears once, in the 9-month tips, as one of three ways a baby might reach a toy: crawl, scoot, or roll.6 A child who went from sitting to standing without crawling has not missed a milestone on that list.
STNR vs ATNR: what is the difference?
The ATNR responds to turning the head to one side and makes the two sides of the body do opposite things; the STNR is assessed with the head bent forward and back, and the two sides respond alike.1,3 Only the ATNR has a documented infant timeline in the standard reference.1
| STNR | ATNR | |
|---|---|---|
| What the head does | Bends forward or back; rated in flexion and in extension3 | Turns to one side1 |
| Window in the standard reference | None given1 | Appears around 35 weeks of gestation; integrates by 3 to 4 months1 |
| Among the three most often still active at ages 3 to 11 | Yes2 | Yes2 |
| Correlation with ADHD in a meta-analysis of 229 children | r = 0.394 | r = 0.484 |
They are usually named together because they are tested together, and the main evidence on attention, the meta-analysis below, covers both.4 The ATNR has its own page, with the obligatory-versus-facultative distinction that matters in infancy, and so does the TLR.
What does the evidence show about a retained STNR and attention?
It is one of the three found most often. A 2026 systematic review of 14 studies in children aged 3 to 11 without neurodevelopmental diagnoses found the ATNR, the STNR and the TLR to be the reflexes most frequently observed still active.2
The ADHD association has a number on it. A meta-analysis of four studies and 229 participants found a moderate positive correlation between ADHD and these reflexes: r = 0.48 for the ATNR and r = 0.39 for the STNR.4
How to read r = 0.39. It is a real, moderate association across a group. It is not a test, it does not predict an individual child, and four studies with 229 participants between them is a small base for a strong claim. The same review’s authors describe the field as being at an initial stage.4
The detail inside that number. Broken down by symptom, the STNR correlated with learning problems (r = 0.43) and with impulsivity and hyperactivity (r = 0.36), but showed no significant correlation with anxiety. The authors conclude by calling for longitudinal or experimental studies to establish whether the relationship is causal.4
Motor and academic associations exist too. In the same 2026 review, all six studies of motor development reported negative associations — particularly locomotion, balance and manual dexterity — and six more linked persisting reflexes to lower performance in reading, spelling and mathematics.2 These are associations across groups, not mechanisms in a child.
If W-sitting is what prompted the question, it has its own page, which covers when it matters and when it does not.
Do exercises for a retained STNR work?
Not convincingly yet. The 2026 review found five studies evaluating interventions aimed at reducing persisting reflexes. Most reported improved developmental outcomes, with effect sizes ranging from small to large — and the review concluded in the same breath that the available evidence “remains limited and heterogeneous” and should be read with that in mind.2
A 2026 study of 27 autistic children aged 4 to 10, given a 12-week program aimed at the ATNR, STNR and TLR, reported large gains in motor, sensory and reflex scores; it had no control group, and its authors note that natural development may have contributed.3
That is a fair summary of where this sits: promising enough to study, not settled enough to sell as a course. Occupational therapy guidance is explicit that a retained reflex does not automatically mean impairment.5
What should I ask about a reflex integration recommendation?
Ask what everyday difficulty it targets, how progress will be measured, and where any expected integration age comes from, because occupational therapy guidance ties intervention to everyday outcomes and the standard reference gives the STNR no age.5,1
The questions worth asking are on the parent article, and they matter more here than for the reflexes with clear infant timelines — because with the STNR there is no standard integration age to check the claim against.
Questions to ask
- Which everyday task is this for? Sitting at a desk, copying from the board, ball skills: something you can both see change.5
- How was the STNR tested? Ask which tool; the newest scale is not yet broadly validated.1
- How will we measure progress, and when? A standardized measure of the task, not only a reflex score.5
- Has attention been assessed on its own terms? A reflex score is not an ADHD assessment.4
The full questions to ask a provider are on the parent article. Our page on delayed motor milestones covers when gross motor development needs a closer look, and you can find a pediatric physical therapist near you.
Frequently Asked Questions
What is the STNR?
The symmetric tonic neck reflex. Flexing or extending the neck produces a corresponding change in flexion and extension in the arms and legs. It is described as a brainstem-mediated automatism that typically integrates during the first year of life.
At what age should the STNR integrate?
The standard clinical reference used here names the STNR without giving it an integration window, while giving one for the Moro, ATNR, palmar grasp and Galant. If a program specifies an age, it is worth asking where that age comes from.
Is the STNR linked to ADHD?
A meta-analysis of four studies and 229 participants found a moderate positive correlation — r = 0.39 for the STNR and r = 0.48 for the ATNR. That is a real association across a group. It is not a test, it does not predict an individual child, and it is a small evidence base.
Does skipping crawling mean a retained STNR?
That claim is common and is not established. Crawling is not a milestone every typically developing child passes through the same way, and the reflex literature does not show that skipping it causes later difficulty.
What is the difference between the STNR and the ATNR?
The ATNR is triggered by turning the head to one side, and the two sides of the body respond differently. The STNR is assessed with the head bent forward and back, and both sides respond alike. The standard clinical reference gives the ATNR an integration window of 3 to 4 months and gives the STNR none.
Is crawling a developmental milestone?
Not on CDC's milestone checklists, which list skills most children reach by each age. Crawling is not among them at any age; the 9-month page mentions it only as one of the ways, with scooting and rolling, that a baby might move toward a toy.
Sources
- Chamarthi VS, Gunasekaran V, Daley SF. Primitive Reflexes: Comprehensive Neurological Assessment Across the Lifespan. In: StatPearls. StatPearls Publishing; updated 2026. ncbi.nlm.nih.gov/books/NBK554606 (PMID 32119493). Checked August 25, 2026.
- Provazník A, Musálek M, Bob P, Větrovský T, Malambo C, Silva AF, Anderson D. Persisting primitive reflexes and motor and cognitive development in children: a systematic review. Acta Psychologica. 2026;266:106915. doi:10.1016/j.actpsy.2026.106915 (PMID 42061063).
- Bijle MA, Malawade M. Effectiveness of reflex integration exercises on sensory-motor outcomes in children with autism spectrum disorder: a quasi-experimental study. Cureus. 2026;18(7):e111970. doi:10.7759/cureus.111970 (PMID 42544248).
- Wang M, Yu J, Kim HD, Cruz AB. Attention deficit hyperactivity disorder is associated with (a)symmetric tonic neck primitive reflexes: a systematic review and meta-analysis. Frontiers in Psychiatry. 2023;14:1175974. doi:10.3389/fpsyt.2023.1175974 (PMID 37484683).
- American Occupational Therapy Association. Don’t use reflex integration programs for individuals with delayed primary motor reflexes without clear links to occupational outcomes. Recommendation AOTA8, Choosing Wisely clinician list, July 27, 2021. archived recommendation. Checked October 5, 2026.
- Centers for Disease Control and Prevention. CDC’s Developmental Milestones (Learn the Signs. Act Early.), milestone pages for 2 months to 5 years. cdc.gov/act-early/milestones. Checked October 5, 2026.
- Zubler JM, Wiggins LD, Macias MM, Whitaker TM, Shaw JS, Squires JK, et al. Evidence-informed milestones for developmental surveillance tools. Pediatrics. 2022;149(3):e2021052138. doi:10.1542/peds.2021-052138 (PMID 35132439).
Medical disclaimer. This page is for general educational purposes and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your child. Sensory and motor concerns are best assessed by an occupational or physical therapist who can evaluate your individual child.