Let’s look at primitive reflexes. What are they, and why are they important?
Primitive reflexes are automatic movement survival reflexes that we have as babies. They appear in a particular order in the womb and during the first year of life. As babies use these reflexes and develop through their movement milestones, the reflexes gradually integrate one by one as more mature voluntary and postural control develops. Ideally, most primitive reflexes are integrated during the first year of life as the brain and nervous system mature (Martello, 2023; Leisman & Melillo, 2025).
They include things like the breastfeeding reflex, movement reflexes that help the baby birth, roll and crawl, and reflexes like the startle reflex that help the baby react to unpleasant or startling stimuli. Place your finger in a baby’s palm and they will close their hand to hold your finger. This is the palmar grasp reflex, one of the primitive reflexes commonly seen in newborns (Futagi et al., 2012; Sigafoos et al., 2021).
So why is this important for children and adults?
We were all babies once, and the way we developed and moved through our early milestones plays a huge role in how our bodies and brains developed. Those early months helped shape who we are today.
You may have heard the term neurodivergent. This term is used to describe someone whose neurological development is different from what is considered typical. Sometimes this includes differences in early developmental milestones. For example, a child may not move through milestones in the typical timeframe or may skip some altogether – crawling being a common example. When early movement development is altered, primitive reflexes may also fail to fully integrate (Martello, 2023).
Movement is incredibly important for the developing brain. When babies move, they receive constant sensory feedback through their muscles, joints and senses. This feedback helps build connections in the nervous system and supports brain development. Primitive reflexes originate primarily from lower brain centres in the brainstem, which help babies move and respond to the environment before higher brain areas are fully developed (Leisman & Melillo, 2025).
As development progresses, higher brain centres gradually gain control over these reflexes and inhibit them. This shift allows more mature movement patterns and cognitive functions to develop. These higher brain centres are involved in things like emotional maturity, social interaction, problem solving and higher-order thinking, as well as regulation of the nervous system (Leisman & Melillo, 2025).
When reflexes do not integrate properly, this can create what some researchers describe as “bottom-up interference.” This means lower brain centres continue to drive reflexive responses that can interfere with the functions of higher brain areas (Melillo et al., 2022).
This may contribute to difficulties with movement coordination, emotional regulation, attention, social interaction and learning. Research has shown associations between retained primitive reflexes and neurodevelopmental differences including autism, ADHD, learning disabilities and sensory processing differences (Martello, 2023; Sigafoos et al., 2021; Leisman & Melillo, 2025).
Many people are surprised to learn that primitive reflexes can sometimes remain partially active beyond infancy. When this happens, it can provide useful insight into how the nervous system developed and how movement and sensory systems are functioning.
Some signs that primitive reflexes may still be active can include:
- Coordination difficulties
- Poor balance or posture
- Trouble crossing the midline of the body
- Challenges with handwriting or fine motor skills
- Sensory sensitivities
- Difficulty sitting still or regulating movement
- Emotional reactivity or difficulty regulating stress responses
- Learning challenges such as reading or attention difficulties
These signs can have many different causes, and primitive reflexes are just one piece of the puzzle. However, assessing them can provide valuable information about how the nervous system is functioning and whether targeted movement work may help.
This is why assessing primitive reflexes can be useful, even beyond infancy. Primitive reflexes can be assessed in both children and adults, and it’s actually not uncommon for people to have one or two reflexes still partially retained.
Once reflexes are identified, specific movement-based exercises can be used to encourage integration. Research suggests that sensorimotor and movement-based programs can help reduce primitive reflex retention and improve motor coordination and behavioural outcomes in some populations (Hirose et al., 2025; Tele-Heri et al., 2025).
The goal of these exercises is to reduce the “bottom-up” interference in the nervous system and allow higher brain areas to function more effectively. When the nervous system becomes better integrated, people may notice improvements in movement, coordination, emotional regulation and overall functioning.
Common Primitive Reflexes I Test in Clinic
There are a number of primitive reflexes that can be assessed in both children and adults. In clinic I commonly test the following reflexes:
Root and Suck Reflex
These reflexes help a baby locate and latch onto a food source for feeding. When the cheek or mouth is stimulated, the baby turns toward the stimulus and begins sucking. If these reflexes remain active later in life they can sometimes contribute to oral sensitivities, speech or feeding difficulties.
Snout Reflex
This reflex causes the lips to pucker when the area around the mouth is lightly tapped. It is normally integrated early in infancy. If it remains active it can sometimes influence speech patterns or oral motor control.
Palmar Grasp Reflex
When pressure is placed in a baby’s palm, the fingers automatically close around the object. This reflex supports early grasping behaviour but should integrate as voluntary hand control develops. Retention can sometimes be associated with fine motor challenges such as handwriting or manual dexterity.
Asymmetrical Tonic Neck Reflex (ATNR)
When a baby turns their head to one side, the arm on that side extends while the opposite arm bends, creating the classic “fencing” posture. This reflex supports early rolling and hand-eye coordination. If retained, it may influence posture, coordination, reading, writing, or crossing the midline.
Symmetrical Tonic Neck Reflex (STNR)
This reflex links head movement with arm and leg movement. When the head bends forward, the arms bend and the legs extend; when the head lifts, the opposite occurs. It plays a role in transitioning from crawling to more upright movement patterns.
Tonic Labyrinthine Reflex (TLR)
The TLR relates to head position in space and helps babies learn how to control their body against gravity. If it remains active, it may influence posture, balance, coordination and muscle tone.
Moro Reflex (Startle Reflex)
The Moro reflex is the baby’s automatic startle response. When triggered, the arms move outward and then back in toward the body. This reflex helps babies respond quickly to sudden changes in their environment. If it remains active later in life it can sometimes be associated with heightened stress responses or sensory sensitivity.
Babinski Reflex
When the sole of a baby’s foot is stimulated, the big toe extends upward and the other toes fan out. This reflex normally integrates as the nervous system matures. Persistence beyond early childhood can indicate delayed neurological development.
Spinal Galant Reflex
When the skin along one side of the lower back is stimulated, the trunk curves toward that side. This reflex assists movement through the birth canal and early mobility. If retained, it may be associated with posture, fidgeting, or difficulties sitting still.
Primitive reflex assessment and integration exercises are used as part of a broader physiotherapy and neurological assessment. They are not intended to diagnose neurological or developmental conditions but can provide useful information about movement patterns and nervous system development.
About the Author
Jackie Bollen is a physiotherapist and founder of Reflecting Health, where she specialises in brain-based physiotherapy approaches including primitive reflex integration and hemispheric brain balance. She works with both children and adults to support movement, nervous system regulation and overall wellbeing.
References:
Futagi, Y., Suzuki, Y., & Toribe, Y. (2012). The Grasp Reflex and Moro Reflex in Infants : Hierarchy of Primitive Reflex Responses. International Journal of Pediatrics, 2012(2012), 1–10. https://doi.org/10.1155/2012/191562
Hirose, N., Tashiro, Y., & Takasaki, T. (2025). Effects of a 12-Week Exercise Intervention on Primitive Reflex Retention and Social Development in Children with ASD and ADHD. Children (Basel), 12(8), Article 987. https://doi.org/10.3390/children12080987
Leisman, G., & Melillo, R. (2025). Evaluating Primitive Reflexes in Early Childhood as a Potential Biomarker for Developmental Disabilities. Journal of Paediatrics and Child Health, 61(6), 846–851. https://doi.org/10.1111/jpc.70053
Martello, J. M. (2023). Persistent Primitive Reflex and Developmental Delay in the School-Aged Child. Journal for Nurse Practitioners, 19(10), Article 104767. https://doi.org/10.1016/j.nurpra.2023.104767
Melillo, R., Leisman, G., Machado, C., Machado-Ferrer, Y., Chinchilla-Acosta, M., Kamgang, S., Melillo, T., & Carmeli, E. (2022). Retained Primitive Reflexes and Potential for Intervention in Autistic Spectrum Disorders. Frontiers in Neurology, 13, Article 922322. https://doi.org/10.3389/fneur.2022.922322
Tele-Heri, B., Csapo, K., Szabo, J., Papp, C., Gesztelyi, R., & Zsuga, J. (2025). Effects of a 6-Month Exercise Intervention on Primitive Reflexes in Children with Developmental Language Disorder—A Case for Multisensory and Sensorimotor Integration. Children (Basel), 12(12), Article 1616. https://doi.org/10.3390/children12121616
Sigafoos, J., Roche, L., O’Reilly, M. F., & Lancioni, G. E. (2021). Persistence of Primitive Reflexes in Developmental Disorders. Current Developmental Disorders Reports, 8(2), 98–105. https://doi.org/10.1007/s40474-021-00232-2
