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In Part One, we talked about the importance of looking at Primitive Reflexes as one piece of a much larger neurological picture. A retained reflex may give us useful information, but it doesn’t give us a diagnosis, and it certainly doesn’t explain everything we see in a patient. With that in mind, let’s start with one of the earliest and perhaps most recognizable Primitive Reflexes: the Moro Reflex.

Most of us remember learning about Moro as the “startle reflex”, triggered by making a sudden movement, changing the position of an infant’s head, or creating the sensation that they are falling, and the arms suddenly extend outward before coming back toward the body. But Moro is more interesting than simply watching a baby’s arms move; at its core, Moro is a protective response to sudden change.

Where Does Moro Come From?

The Moro Reflex begins developing before birth. It can be observed in premature infants as early as approximately 25 weeks post-conception and is typically present by about 30 weeks. In the full-term infant, it is a normal and expected part of neurological development. The response we see generally occurs in two phases. First, the infant extends and abducts the arms, often opening the hands, followed by flexion and adduction, bringing the arms back toward the body.

The response can be triggered by a sudden change in head position or balance, particularly the sensation of falling, as well as sufficiently intense stimulation. Importantly, it is the sudden disruption of balance or intensity of stimulation, rather than simply how far the infant moves, that produces the response.

In early life, that makes sense.

A newborn doesn’t yet have mature voluntary motor control, postural stability, or the ability to evaluate a sudden environmental change and decide how to respond. Primitive Reflexes provide automatic responses while more sophisticated neurological systems are developing. The Moro Reflex normally begins to diminish at around three months and should disappear by approximately six months, which is where the idea of “integration” becomes important.

We commonly say that the Moro Reflex becomes integrated. That language is useful clinically, but neurologically, it can give the impression that the underlying circuitry simply disappears. A better way to think about Primitive Reflex development may be that, as the nervous system matures, higher neurological systems increasingly regulate and inhibit primitive responses while more sophisticated voluntary, postural, and sensory-motor responses develop. The infant doesn’t simply lose a response; rather, the nervous system develops better ways of responding.

What Happens When Moro Persists?

This is where things become much more interesting.

Clinical literature has associated persistence of Primitive Reflexes, including Moro, beyond their expected developmental period with neurodevelopmental concerns. Descriptions of retained Moro frequently include heightened reactivity, hypervigilance, sensory-processing difficulties, poor impulse control, disrupted attention, anxiety, and difficulties with emotional regulation. But we should pay special attention to an important word in that sentence: associated.

A retained Moro reflex does not mean a child has anxiety. It doesn’t mean Moro caused poor attention. And it certainly does not mean every child who startles easily has a retained Moro reflex. Instead, perhaps a retained Moro gives us another piece of information about how that person’s nervous system responds to stimulation, and because Moro is a whole-body response, I think it is useful to consider its possible impact from several different directions.

The Physical Side of a Retained Moro

The infant Moro response involves much more than movement of the arms.

It occurs in response to a sudden disruption of balance or intense stimulation and involves a developing nervous system that is simultaneously learning to organize head control, posture, movement, vestibular information, proprioception, and responses to gravity. As development progresses, the child develops increasingly sophisticated ways of responding to movement and changes in position. Head control improves. Righting and postural reactions emerge. Balance becomes more efficient. Voluntary movement becomes more precise. The nervous system no longer needs the same primitive whole-body response every time something unexpected happens. If Moro remains unusually active beyond the period when we would expect it to be well regulated, we might ask whether unexpected movement or sensory input is requiring more of the patient’s nervous system than we realize.

Does the patient tolerate movement well? What happens when the head moves unexpectedly? How secure is the patient when balance is challenged? Does sudden sensory input interrupt an ongoing motor task? Does the patient become physically tense or disorganized when the environment becomes unpredictable? These are observations, not diagnoses.

Balance, posture, coordination, sensory processing, and motor control are enormously complex, and a retained Moro cannot explain all of those systems, but it may give us another reason to look carefully at how efficiently the patient’s visual, vestibular, proprioceptive, and postural systems are working together.

And that brings us directly to vision.

Moro and Visual Development

We sometimes talk about visual development as though the eyes are learning their skills independently from the rest of the body, even though it is proven that they aren’t. From infancy onward, vision develops while the child is learning to control the head, orient to gravity, maintain balance, reach, roll, sit, crawl, stand, and eventually move through space. Basically, the eyes, head, and body are learning to work together. Visual information helps guide movement. Vestibular information tells the nervous system about head movement and position. Proprioceptive information helps establish where the body is in space. Postural systems provide the physical stability from which increasingly precise visual behaviors can develop. That relationship becomes particularly interesting when we think about Moro because one of its primary triggers is an unexpected disruption of balance or change in head position.

Imagine trying to develop stable visual attention while movement of the head repeatedly demands an unnecessarily large neurological response. Or even worse, trying to maintain fixation while the nervous system is simultaneously working hard to manage balance and body position. Have you ever tried to follow a moving target while peripheral movement, sound, head position, and vestibular information are all competing for attention?

We cannot say that a retained Moro causes poor fixation, tracking, convergence, accommodation, or another binocular vision disorder. The research does not support making that leap. There is, however, emerging research examining relationships between persistent Primitive Reflexes and differences in fixation and ocular motility. That research is interesting, but it remains developing and does not establish causation.

Perhaps an even more useful concept for us clinically is visual stability. Efficient vision requires the nervous system to maintain useful visual information despite the fact that our bodies and our environments are constantly moving. We turn our heads, we walk, objects move around us, people enter our peripheral vision, our balance shifts, sounds occur, and lighting changes. Yet somehow we continue reading the page, tracking a ball, navigating a crowded room, or maintaining eye contact during a conversation, which requires incredible cooperation among the visual, vestibular, proprioceptive, postural, motor, and attentional systems.

If unexpected movement or sensory stimulation continually produces an excessive response, maintaining visual stability may require more effort.

For the Vision Therapist, that creates some interesting questions. What do we observe about fixation when the patient’s head moves? What happens to eye movements when balance becomes more challenging? Can the patient maintain visual attention while moving? What happens when peripheral visual stimulation is introduced? Can the patient continue a visual task while auditory and vestibular information compete for attention? Does visual performance change as sensory load increases?

Those questions don’t require us to claim that Moro caused the visual problem; rather, they simply recognize that vision is operating inside the same nervous system.

The Emotional Side of Moro

The emotional side may initially seem very different from posture, balance, and visual stability, but the nervous system doesn’t necessarily divide itself that neatly. As mentioned above, Moro is fundamentally a protective response to sudden change. Clinical descriptions of persistent Moro include associations with hypervigilance, anxiety, sensory-processing difficulties, poor impulse control, disrupted attention, and difficulties with emotional regulation.

But remember, association is not causation.

A retained Moro doesn’t diagnose anxiety, nor does it tell us someone has an emotional disorder, and it never permits us to predict that one will develop. But consider the experience of a nervous system that is unusually reactive to its environment:

Unexpected movement gets your attention, noise gets your attention, something moving through your peripheral vision gets your attention, a change in balance gets your attention, a busy environment becomes harder to filter. Even if the complete infant Moro response isn’t occurring every time, what might heightened reactivity do to attention? What might it do to sensory tolerance? How much energy might be spent continually determining which sensory information matters and which can safely be ignored?

Now add a difficult visual task.

The patient is being asked to maintain posture, stabilize the head, control the eyes, process visual information, ignore competing sensory input, sustain attention, remember what they are doing, and produce an appropriate response.

If those processes require considerably more effort than they should, eventually what we see may look emotional.

Frustration. Avoidance. Irritability. Anxiety. Anger. Tears. Shutting Down.

That doesn’t mean Moro produced the emotional response. The emotional response may reflect the cumulative experience of repeatedly being asked to function in an environment that requires more neurological effort from this patient than it does from someone else, which is where the physical, visual, and emotional sides of Moro begin to come together. Because the patient doesn’t arrive in our therapy room as a visual system, a vestibular system, a motor system, and an emotional system. They arrive as one person.

When Emotional Regulation Becomes Something More

Although there is an association between a retained Moro Reflex and emotional dysregulation, and research outside the Primitive Reflex literature has demonstrated relationships between emotional dysregulation and more significant psychological distress, including suicidal ideation and behavior, it is important that we are abundantly clear: there is no research which establishes a connection between the Moro Reflex and suicide, and we should never imply that it does, as suicide is complex and multifactorial. But if someone we are working with expresses significant hopelessness, emotional distress, or thoughts of self-harm, we should never dismiss what they are telling us as simply part of a retained reflex. The reflex finding and the patient’s emotional state are separate pieces of information.

As Vision Therapists, we may find ourselves in a unique position. We may spend thirty, forty-five, or sixty minutes one-on-one with the same patient every week, sometimes for months. During that time, patients talk. They tell us about school, work, relationships, frustrations, successes, and sometimes things that have very little to do with why they originally walked into our office. We don’t need to become mental health professionals, but we do need to know when to listen a little more carefully, without assuming the emotional dysregulation is Moro related. Obviously, we are not in a position to diagnose the psychological piece; however, our responsibility is to recognize when what we are hearing extends beyond our expertise and make sure it reaches the appropriate person, whether that is the supervising doctor, a parent or guardian when appropriate, or another qualified healthcare professional.

Although a retained Moro may offer one piece of information about neurological dysregulation, it should never prevent us from hearing what the patient is actually telling us.

What Happens After Brain Injury?

This is another area where Moro becomes particularly interesting.

A person can go decades without anyone thinking about their Moro Reflex. Then they experience a concussion or other traumatic brain injury and suddenly struggle with motion, balance, busy visual environments, light, noise, eye movements, convergence, accommodation, attention, autonomic regulation, or emotional regulation. We know that traumatic brain injury can disrupt many of these systems.

Visual problems following concussion are well documented. Difficulties involving convergence, accommodation, smooth pursuits, saccades, and the vestibulo-ocular reflex have all been reported following concussion.

The area that is much less clear is whether it is accurate to say that the Moro reflex itself has actually “returned.” Neurologically, Primitive Reflexes normally come under increasing higher-level inhibition and regulation during development. Neurological injury can interfere with inhibitory control, and the appearance of certain primitive or “release” reflexes in adults is a recognized neurological phenomenon; however, most of the established adult neurological literature describes reflexes such as grasping, rooting, snout, or palmomental responses. Evidence specifically demonstrating that concussion routinely causes the developmental Moro reflex to re-emerge is much more limited.

So I think we need to be careful.

If a patient following brain injury suddenly demonstrates increased startle, sensory sensitivity, vestibular intolerance, emotional reactivity, or movement patterns that resemble a primitive response, implying their “Moro came back” seems to be an over-simplification.

Perhaps the position is to consider the question:

“Has this injury changed the nervous system’s ability to regulate a protective response that was previously under effective higher-level control?”

We may not yet know the answer, but I think it is a question worth asking. For those of us working with brain injury patients, it reinforces the importance of looking beyond any single visual finding. The patient struggling with convergence may also be struggling with vestibular processing. The patient who can’t tolerate a busy visual environment may also be dealing with sensory overload. The patient who becomes anxious during movement may be experiencing something very different neurologically from someone who simply doesn’t want to participate, since the systems interact.

What Does the Research Actually Tell Us?

This is where I think it becomes especially important to separate what we know from what we suspect.

We know that Moro is a normal Primitive Reflex in infancy. It appears before birth, is present in the full-term infant, begins to diminish during the first several months of life, and normally disappears by approximately six months. We know that persistence of primitive reflexes beyond their expected developmental period can be associated with neurological or neurodevelopmental concerns. There is clinical literature associating persistent Moro with hypervigilance, sensory-processing difficulties, attention and impulse-control difficulties, anxiety, and emotional dysregulation. There is emerging research examining relationships between retained Primitive Reflexes and fixation and ocular-motor findings. We also have substantial evidence that Traumatic Brain Injury can disrupt visual and vestibular systems, including convergence, accommodation, pursuits, saccades, and vestibulo-ocular function. Although research outside the Primitive Reflex literature demonstrates relationships between emotional dysregulation and psychological distress, we do not currently have sufficient evidence to say:

• Retained Moro causes anxiety
• Retained Moro causes a particular binocular or ocular-motor disorder
• Retained Moro is a predictor of psychiatric conditions
• Integrating Moro will treat an emotional disorder
• A concussion routinely causes the Moro reflex to return

Those are much stronger claims than the current evidence supports, and acknowledging those limitations makes the conversation more useful, not less.

What Should the Vision Therapist Take Away?

Perhaps the most useful thing about identifying a retained Moro isn’t the ability to attach another label to the patient, but instead the opportunity to observe more carefully. What happens when the patient’s head position changes? What happens when we introduce movement? What happens when balance becomes more challenging? What happens when the visual environment becomes busier? What happens when auditory, visual, and vestibular demands occur at the same time? Does visual performance deteriorate? Does posture change? Does attention disappear? Does the patient become overwhelmed?

And perhaps most importantly:

How much effort is this nervous system using to accomplish something that we hope will eventually become automatic?

Those observations may tell us considerably more than simply recording “Retained Moro” on an evaluation form. The Moro Reflex reminds us that vision develops inside a nervous system that is simultaneously learning to move, balance, orient to gravity, filter sensory information, regulate arousal, and respond to the world around it. A retained Moro Reflex may be one small clue that helps us understand how that nervous system is organizing and how hard it may be working.

It is not a diagnosis, and it is not an explanation for everything we’re seeing. It is but one more piece of information about the whole person sitting in front of us, and perhaps one more reason to ask better questions.

Stay tuned for Part Three: the Tonic Labyrinthine Reflex (TLR) and the developing relationship between gravity, posture, and vision.

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References

Rogier G, Chiorri C, Beomonte Zobel S, Muzi S, Pace CS, Cheung MW-L, Velotti P. The multifaceted role of emotion regulation in suicidality: Systematic reviews and meta-analytic evidence. Psychological Bulletin. 2024;150(1):45–81. doi:10.1037/bul0000415. PMID: 38376911.

Pattnaik P, Al Khalili Y. Moro Reflex. [Updated August 2, 2025]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026. PMID: 31194330.

Chamarthi VS, Gunasekaran V, Daley SF. Primitive Reflexes: Comprehensive Neurological Assessment Across the Lifespan. [Updated June 17, 2026]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026. PMID: 32119493.

Pecuch A, Gieysztor E, Wolańska E, Telenga M, Paprocka-Borowicz M. Primitive Reflex Activity in Relation to Motor Skills in Healthy Preschool Children. Brain Sciences. 2021;11(8):967. doi:10.3390/brainsci11080967. PMID: 34439585.

Gieysztor EZ, Choińska AM, Paprocka-Borowicz M. Persistence of primitive reflexes and associated motor problems in healthy preschool children. Archives of Medical Science. 2018;14(1):167–173. doi:10.5114/aoms.2016.60503. PMID: 29379547.

Domingo-Sanz VA. Persistence of Primitive Reflexes Associated with Asymmetries in Fixation and Ocular Motility Values. Journal of Eye Movement Research. 2024;17(2):1–33. doi:10.16910/jemr.17.2.5. PMID: 39246715.

Master CL, Bacal D, Grady MF, Hertle R, Shah AS, Strominger M, Whitecross S, Bradford GE, Lum F, Donahue SP. Vision and Concussion: Symptoms, Signs, Evaluation, and Treatment. Pediatrics. 2022;150(2):e2021056047. doi:10.1542/peds.2021-056047. PMID: 35843991.

Master CL, Bacal D, Grady MF, Hertle R, Shah AS, Strominger M, Whitecross S, Bradford GE, Lum F, Donahue SP. Evaluation of the Visual System by the Primary Care Provider Following Concussion. Pediatrics. 2022;150(2):e2021056048. doi:10.1542/peds.2021-056048. PMID: 35909153.

Wallace B, Lifshitz J. Traumatic brain injury and vestibulo-ocular function: current challenges and future prospects. Eye and Brain. 2016;8:153–164. doi:10.2147/EB.S82670.

Rogante E, Cifrodelli M, Sarubbi S, Costanza A, Erbuto D, Berardelli I, Pompili M. The Role of Emotion Dysregulation in Understanding Suicide Risk: A Systematic Review of the Literature. Healthcare. 2024;12(2):169. doi:10.3390/healthcare12020169. PMID: 38255058.