Testing primitive reflexes involves applying a specific stimulus and watching for an involuntary, stereotyped movement that healthy nervous systems produce during a defined window of development. These reflexes are hardwired into the brainstem and spinal cord, present in utero, and gradually suppressed as higher brain centers mature during the first year or two of life. Clinicians check them in newborn exams, developmental screenings, and neurological workups at any age, because their presence or absence at the wrong time can flag problems ranging from cerebral palsy to dementia. The techniques are straightforward, but each reflex has its own trigger, expected response, and timeline.
Moro Reflex
The Moro reflex is usually the first reflex parents notice and one of the first clinicians check. To elicit it, support the infant in a semi-reclined position with one hand under the head and the other under the back. Then let the head drop back slightly, about two to three centimeters, while still keeping your hand underneath as a safety net. The baby’s arms should fling outward with fingers spread, then pull back in toward the body in an embracing motion. The outward fling and the inward return are both part of the full response. Research distinguishes the initial rapid extension, which overlaps with a startle reflex driven by the brain’s fear circuitry, from the slower adduction phase that follows, which is the true Moro component.1PubMed. The Moro reaction: More than a reflex, a ritualized behavior of nonverbal communication
A normal Moro reflex is present at birth in full-term infants and typically fades by four to six months. In premature babies, it can appear as early as 25 weeks post-conceptional age and becomes more consistently elicitable by about 30 weeks.2Pediatric Research. The Evolution of Primitive Reflexes in Extremely Premature Infants An absent Moro at birth or a clearly asymmetric response, where one arm moves normally and the other stays limp, can point to brachial plexus injury, a fractured clavicle, or a neurological issue on one side. A Moro that persists well past six months suggests the cortex is not inhibiting lower brain circuits on schedule.
Palmar and Plantar Grasp Reflexes
The palmar grasp is tested by placing your finger or a small rod in the baby’s open palm from the ulnar (pinkie) side. A normal response is a firm, involuntary grip that can be strong enough to partially support the infant’s weight if you lift gently, though you should never rely on it. This reflex is present from at least 25 weeks post-conceptional age and usually disappears by about five to six months, as voluntary reaching and grasping take over.2Pediatric Research. The Evolution of Primitive Reflexes in Extremely Premature Infants
The plantar grasp works similarly but on the foot. Press your thumb firmly against the ball of the infant’s foot, just behind the toes, and the toes should curl downward as if gripping your thumb. This reflex is present in all normal infants from 25 weeks post-conceptional age and persists until roughly the end of six months of corrected age.3PubMed. Neural mechanism and clinical significance of the plantar grasp reflex in infants Its disappearance is clinically meaningful: absence of the plantar grasp from three months onward has been linked to the later development of spastic cerebral palsy.4PubMed. Plantar grasp reflex in high-risk infants during the first year of life That makes it one of the more useful early screening signs in babies who are already considered high-risk due to prematurity or birth complications.
Asymmetric Tonic Neck Reflex
The asymmetric tonic neck reflex, often called the ATNR or “fencer’s pose,” is tested with the infant lying on their back. Turn the baby’s head to one side and hold it there for a few seconds. The arm and leg on the face side should extend, while the arm and leg on the skull side flex. The result looks like the baby is striking a fencing pose. You should see the pattern on both sides, so test with the head turned to the left and to the right.
The ATNR normally appears around the time of birth and integrates, meaning the cortex overrides it, by about six months. In premature infants, it can be present as early as 25 weeks post-conceptional age but is not reliably and consistently triggered until closer to 30 weeks.2Pediatric Research. The Evolution of Primitive Reflexes in Extremely Premature Infants The clinical concern with the ATNR is not so much its absence in early infancy as its persistence later. A retained ATNR past six months interferes with hand-eye coordination, midline crossing, and the ability to bring both hands together in front of the body. Those are skills a child needs for feeding, crawling, and eventually writing.
Symmetric Tonic Neck Reflex
The symmetric tonic neck reflex, or STNR, is different from the ATNR despite the similar name. It links head position to the limbs in a front-to-back pattern rather than left-to-right. To test it, hold the infant in a supported position on all fours or across your lap so the trunk is roughly horizontal. When the head is flexed downward (chin toward chest), the arms should flex and the legs extend. When the head is extended upward (looking at the ceiling), the arms extend and the legs flex.
The STNR shows up around six to nine months in typical development and normally integrates by about twelve months. It is thought to help bridge the gap between belly crawling and hands-and-knees crawling. A retained STNR can make it difficult for a child to sit still at a desk, because any head movement to look down at paper or up at a board triggers involuntary tone changes in the limbs. This is one reason the STNR has drawn particular research interest in children with attention and behavior difficulties.
Rooting and Sucking Reflexes
Rooting is triggered by stroking the corner of the infant’s mouth or cheek. The baby should turn toward the stimulus with an open mouth, searching for a nipple. Sucking is elicited by placing a clean finger or pacifier in the baby’s mouth; a rhythmic suck-swallow pattern should follow. Both reflexes are present at birth in full-term infants and fade between three and four months as voluntary feeding behavior develops.
Weak or absent rooting and sucking in a newborn are red flags for neurological depression, whether from medication, birth asphyxia, or a congenital issue. In premature infants, coordinated sucking strong enough to support oral feeding often does not mature until around 34 weeks post-conceptional age, which is one practical reason very early preemies are tube-fed initially.
Babkin Reflex
The Babkin reflex, sometimes called the hand-mouth reflex, is less widely known but simple to test. Apply pressure to the palms of both hands simultaneously. The expected response in a young infant is head flexion, head rotation toward the midline, and opening of the mouth.5Pediatrics. THE HAND-MOUTH REFLEX OF BABKIN IN PREMATURE INFANTS The reflex connects hand sensation to oral behavior, likely an early component of the hand-to-mouth coordination that supports feeding. It typically disappears by about three to four months. Clinicians do not test the Babkin as routinely as the Moro or grasp, but it can be useful as part of a broader reflex profile when there are concerns about brainstem integrity.
Galant Reflex
The spinal Galant reflex, also called lateral trunk incurvation, is tested by holding the infant in a prone (face-down) position, supporting the belly with one hand. Stroke or lightly scratch along one side of the spine from the shoulder blade area down toward the buttock. The baby should flex the trunk toward the stimulated side, curving the body like a C. Then repeat on the opposite side.
This reflex is present from around 25 to 30 weeks post-conceptional age and normally integrates by about nine months.2Pediatric Research. The Evolution of Primitive Reflexes in Extremely Premature Infants A retained Galant past its expected window has been associated with fidgeting, restlessness, and difficulty sitting still, because any pressure against the lower back, like leaning against a chair, triggers an involuntary wiggle. Research on children with ADHD has found that those children tend to show a higher occurrence of retained Moro and Galant reflexes compared to peers without ADHD, suggesting these unfinished developmental stages may contribute to some of the restlessness seen in the condition.6Activitas Nervosa Superior. Retained Primitive Reflexes and ADHD in Children
Tonic Labyrinthine Reflex
The tonic labyrinthine reflex, or TLR, is driven by the vestibular system and linked to head position relative to gravity. There are two components. In the forward TLR, when the infant is tilted face-down past horizontal, the limbs should flex and curl inward. In the backward TLR, when the infant is tilted face-up past horizontal, the limbs should extend and stiffen. You can test these by gently tilting the baby forward and backward while supporting them securely.
The TLR helps establish early muscle tone and awareness of body position in space. It typically integrates by about four months in the forward direction and longer for the backward component. A child who still shows a strong TLR past these windows may struggle with balance, spatial awareness, and coordination, because any change in head position involuntarily alters limb tone.
Stepping and Placing Reflexes
The stepping reflex is elicited by holding the infant upright with feet touching a flat surface. The baby should make alternating stepping movements, as if walking. The placing reflex is triggered by brushing the top (dorsum) of the foot against the underside of a table edge; the infant lifts the foot up and over the edge as if to step onto the surface. Both reflexes are present at birth but can be inconsistent, and longitudinal studies in premature infants show that stepping and placing are the slowest of the major primitive reflexes to become consistently elicitable, sometimes not becoming reliable even at term age.2Pediatric Research. The Evolution of Primitive Reflexes in Extremely Premature Infants
These reflexes tend to fade by about two months, though the stepping reflex can be “hidden” for a period before voluntary walking emerges around twelve months. Absence at birth is not always concerning if other reflexes are normal, given their natural inconsistency. But a clear asymmetry, stepping well on one leg and poorly on the other, warrants further investigation.
Standardized Assessment Scales
Checking one reflex in isolation tells you something, but checking a battery of reflexes in a standardized way tells you much more. A quantitative approach was developed decades ago that tracked nine primitive reflexes longitudinally in hundreds of normal infants from birth to two years, establishing normative data for when each reflex should be strongest and when it should fade.7Wiley Online Library (Developmental Medicine & Child Neurology). Primitive reflex profile: a quantitation of primitive reflexes in infancy Having that baseline is what allows clinicians to say whether a reflex is truly “retained” or just at the tail end of its normal range.
More recently, researchers have developed structured scales specifically for school-age children, where the concern shifts from absent reflexes to retained ones. One such scale, the Children’s Primitive Reflex Integration Assessment Scale, covers seven dimensions including the Moro, ATNR, STNR, TLR, Galant, spinal Perez, and Landau reflexes across seventeen test items.8PubMed Central. Development of the children’s primitive reflex integration assessment scale A separate validated test battery for the ATNR, STNR, and TLR administered to over 240 schoolchildren found that some degree of retained primitive reflexes showed up in the vast majority of the children tested.9MDPI / Applied Sciences. Development of Asymmetrical, Symmetrical Tonic Neck Reflex Test and Tonic Labyrinth Reflex Test (TASHUN) for the Assessment of Neurotypical Children: Validity and Reliability That finding is worth sitting with: having a trace of a retained reflex does not automatically mean something is wrong. The clinical question is about degree and whether it is causing functional problems, not simply whether a reflex is detectable at all.
When Retained Reflexes Matter in Children
The research linking retained primitive reflexes to developmental and behavioral difficulties has grown substantially. ADHD has drawn the most attention. A meta-analysis pooling data from multiple studies found a moderate positive correlation between ADHD and retained ATNR and STNR, meaning children with ADHD are more likely to show persistent versions of these reflexes than their peers.10PubMed Central. Attention deficit hyperactivity disorder is associated with (a)symmetric tonic neck primitive reflexes: a systematic review and meta-analysis Interestingly, the pattern appears to differ by sex: ADHD symptoms and balance problems have been linked specifically to persistent ATNR in girls and persistent STNR in boys.11PubMed Central. Disinhibition of Primitive Reflexes in Attention Deficit and Hyperactivity Disorder: Insight Into Specific Mechanisms in Girls and Boys
It is important to understand what these correlations do and do not mean. Retained reflexes are not the cause of ADHD in the way a virus causes an infection. The thinking is more that both the reflex retention and the ADHD symptoms reflect an underlying difference in how the nervous system matured. Screening for retained reflexes in school-age children who are struggling with attention, coordination, or behavior can add useful information to the clinical picture, but a positive finding on a reflex test is not a standalone diagnosis of anything.
Reflex Testing in Preterm Infants
Preterm babies present a unique challenge for reflex testing because the timeline is shifted. All the standard reflexes emerge over the course of fetal development, and being born early does not accelerate that process. A landmark longitudinal study of extremely premature infants found three distinct emergence patterns. The grasp reflexes, both palmar and plantar, were the earliest and most reliably present, showing up in all premature infants from 25 weeks onward. The Moro, ATNR, and Galant appeared in some babies at 25 weeks but were not consistently present until about 30 weeks. The stepping, placing, and positive support reflexes were the latest to develop and were still inconsistent even at full-term equivalent age.2Pediatric Research. The Evolution of Primitive Reflexes in Extremely Premature Infants
The practical takeaway for clinicians and parents is that reflex assessments in preterm infants should always be interpreted against corrected age, not chronological age. A baby born at 28 weeks who is now twelve weeks old is neurologically closer to 40 weeks, not to a three-month-old born at term. Reflexes that would be concerning if absent in a full-term three-month-old may be perfectly normal for that baby’s level of brain maturation.
Primitive Reflexes Reappearing in Adults
Primitive reflexes are not strictly a pediatric topic. When the cortex loses its ability to suppress brainstem activity, whether through dementia, stroke, or other forms of brain damage, these reflexes can re-emerge. In neurology, they are called “frontal release signs” because they often indicate that the frontal lobes have lost their inhibitory control. The reemergence of primitive reflexes in older adults is frequently observed in various types of dementia and reflects diffuse cerebral dysfunction.12Srpski arhiv za celokupno lekarstvo. Primitive reflexes in developing and adult brain – from intellectual disability to dementia
The reflexes most commonly tested for in adult neurological exams include the palmomental reflex (scratching the palm produces a chin twitch), the glabellar tap (repeatedly tapping the forehead between the eyebrows to see if the patient keeps blinking instead of habituating), the snout reflex (tapping the upper lip causes a puckering response), and the grasp reflex (placing an object in the patient’s palm triggers involuntary gripping they cannot easily release). Research on elderly community residents with cerebrovascular disease has examined the prevalence of these frontal release signs and their relationship to cognitive and mood-related variables.13International Journal of Geriatric Psychiatry. Primitive reflexes in cerebrovascular disease: a community study of older people with stroke and carotid stenosis
Finding one frontal release sign in an older adult does not by itself confirm dementia. Some studies have found isolated primitive reflexes in otherwise healthy elderly people. The concern escalates when multiple signs appear together, especially alongside memory problems, personality changes, or declining daily function. In that context, the return of reflexes the person’s brain suppressed in infancy serves as a tangible marker that cortical control is slipping.
Practical Tips for the Exam
Technique matters more than most people realize when testing reflexes. A few principles apply across the board:
- State of the infant: A sleeping, crying, or very hungry baby will give unreliable results. Test during a quiet, alert state when possible.
- Symmetry over presence: For reflexes like the Moro, grasp, and ATNR, asymmetry is often more concerning than a weak response on both sides. One-sided absence may point to a peripheral nerve injury or focal brain lesion, while bilateral weakness suggests a more generalized issue.
- Repetition: If a reflex does not appear on the first attempt, try again after a brief rest. Fatigue or habituation can temporarily suppress a response. But if it consistently fails to appear across multiple attempts, note the absence.
- Corrected age: As discussed for preterm infants, always interpret the reflex profile against corrected gestational age, not the calendar age from birth.
- Documentation: Record not just whether the reflex was present or absent, but its strength (strong, weak, trace) and completeness (full pattern versus partial). This is what quantitative reflex profiles are designed to capture, and it makes follow-up comparisons far more useful than a simple yes/no.
The testing techniques themselves are not difficult to learn, and many of them can be demonstrated by a pediatrician in minutes. Where the skill really lies is in interpreting the constellation of findings: which reflexes are present, which are absent, how strong they are, and whether the overall pattern matches the infant’s developmental stage. A single unexpected finding is a reason to monitor. A cluster of abnormal reflexes is a reason to refer for further evaluation.
Who Should Be Doing the Testing
In clinical settings, primitive reflex assessment is standard practice for pediatricians, neonatologists, pediatric neurologists, and developmental therapists. Occupational therapists and physiotherapists who work with children often perform reflex screening as part of their intake evaluations, especially when a child has been referred for coordination problems, learning difficulties, or sensory issues. Some schools and child development programs have begun incorporating basic reflex screening as well.
There is also a growing cottage industry of non-clinical practitioners offering “retained reflex integration” programs, often combining reflex testing with exercise-based interventions. Some of these draw on legitimate research, and the standardized assessment tools being developed in the peer-reviewed literature are designed to be administered by trained professionals outside of hospital settings.8PubMed Central. Development of the children’s primitive reflex integration assessment scale But the quality and rigor vary enormously. If you are having your child’s reflexes tested outside a clinical setting, it is reasonable to ask what standardized protocol is being used, what the tester’s training background is, and whether positive findings will be shared with the child’s physician for context. A reflex test is a screening tool, not a diagnosis, and it is most valuable when interpreted alongside the child’s full developmental and medical history.