Out of Sight, Still in Mind: What Object Permanence Really Means for Neurodivergent Kids
By Heather Weigel, MAT; edited by Mary McKone, Ed.D.
Before bed, you remind your teenage daughter that her lunch is in the fridge. The next morning, she leaves without it for the third time this week. "I totally forgot it was in there," she says.
Online, this kind of forgetting is often called "object permanence," especially in conversations about ADHD. The experience is real, but the term comes from infant development, where it means knowing that things still exist when we can't see them. Your daughter knows her lunch exists. She just didn't remember it in time. Acting on what we know, when we need to, is the harder skill, and it starts developing in the first year of life through movement.
What is Object Permanence?
The idea comes from Jean Piaget, a Swiss psychologist whose mid-1900s work laid the foundation for the study of children's thinking. In one simple test, Piaget hid a toy under a cloth while a baby watched. Before about 8 months, babies acted as if the toy no longer existed. After that, most lifted the cloth to find it. Piaget concluded that babies build their understanding of the world through action: reaching, grasping, and searching.
Decades later, developmental psychologist Renée Baillargeon measured attention instead of action, because babies look longer at surprising events. In a 1985 study, 5-month-olds watched a screen swing back like a drawbridge toward a hidden box. When the screen seemed to pass straight through the box, the babies stared longer, as if they had seen a magic trick. Their surprise suggested they still expected the box to be there.
Together, these findings suggest babies may know a hidden object exists months before they can act on that knowledge, though researchers still debate how much a long look reveals. Piaget's test measured more than knowledge. To find the toy, babies must remember where it went, resist reaching to the old spot, and move their hand intentionally. A famous infant error shows which part of that system is still under construction.
The A-not-B Moment
Picture a 9-month-old sitting in front of two cups. An adult hides a toy under Cup A, and the baby finds it. After a few rounds, reaching toward A becomes a habit. Then, as the baby watches, the adult hides the toy under Cup B, waits a few seconds, and lets the baby search. The baby reaches for Cup A again.
This is the A-not-B error, and it isn't a lapse in understanding. The baby saw the toy go under Cup B, and babies this age do much better when they can reach right away. The trouble shows up during the wait, because the task depends on two developing skills. Working memory holds information in mind for a few seconds, like a note on a whiteboard: "The toy is at B." Inhibitory control works like a brake pedal, stopping a well-practiced action, like the reach toward A, from taking over.
Both skills depend on the dorsolateral prefrontal cortex, a region at the front and upper sides of the brain. In a 1989 study, babies 7½ to 9 months old made the A-not-B error after delays of only 2 to 5 seconds, but by 12 months they succeeded after 10 seconds. Adult monkeys with damage to this region made the same error, while monkeys with damage elsewhere did not. Together with brain recordings showing frontal activity rising as babies begin to pass the task, these results suggest the younger babies' errors reflect a region that hasn't finished maturing.
However, a maturing prefrontal cortex is only part of the picture. How well the whiteboard and brake work at any moment also depends on alertness, which is controlled deep in the brainstem by the reticular activating system (RAS). This network sends chemical messengers up to the cortex, both directly and through the thalamus, the brain's relay station. The RAS releases norepinephrine, and neighboring midbrain cells release dopamine. In the prefrontal cortex, norepinephrine helps keep the note on the whiteboard during a delay, and dopamine helps screen out distractions.
These chemicals follow a "Goldilocks" pattern. Moderate levels, typical of a calm and interested state, strengthen working memory. Too little, as in drowsiness, or too much, as in stress, weakens it. Under high stress, the balance tips away from the prefrontal cortex and toward the amygdala, favoring fast, automatic reactions. The brake weakens, and old habits take over.
Most of this research comes from adults and animals, but the lesson for parents is practical. For a 9-month-old at the cups or a teenager at the front door, holding something in mind depends on how alert or stressed they are in that moment, not just on brain maturity. A tired, overstimulated, or anxious child may lose track of something they know perfectly well.
So the A-not-B error reflects a whole system still maturing, from the brainstem to the prefrontal cortex. That system doesn't develop on a fixed timetable; what the baby's body is doing shapes it.
Movement Builds the Mind
Piaget's idea that babies learn through action holds up in a modern form. To find a hidden toy, a baby has to look where it went, keep their body steady, and reach intentionally instead of following an old pattern. Each of those abilities grows out of movement. And a baby's first movements aren't chosen at all.
Reflexes Come First
Newborns arrive with primitive reflexes, automatic movements that begin before birth and help babies feed, protect themselves, and hold their bodies against gravity. Many of these responses are coordinated by the reticular formation, a web of more than 100 cell clusters in the brainstem that also contains the RAS. One part sends signals up to set alertness. Another sends signals down the spinal cord to control muscle tone, posture, balance, and protective reflexes. Early on, this network runs much of the show. A baby whose head position, startle, and grip are still mostly automatic can't yet direct their body toward a hidden toy.
Integration: The Body’s First Brake Pedal
Reflexes don't simply switch off. Instead, as the brain matures, higher systems learn to hold them back and fold them into purposeful movement. Specialists call this process integration. Current research describes it as inhibition at several levels at once: the spinal cord, the brainstem, and the motor cortex, the strip of brain that directs voluntary movement and fits each response to the situation.
That top-down braking resembles the work the prefrontal cortex does in the A-not-B task, where an intended action overrides an automatic one. The timelines overlap, too. Babies gain control over automatic hand and body reactions through the middle of the first year, leading up to the months when they learn to override the reach toward Cup A.
What Each Reflex Gives Way To
Each reflex has a typical window, and what replaces it adds a skill a baby needs to find hidden objects. Sources vary on the exact ages.
Asymmetric tonic neck reflex (ATNR). Often called the "fencing" reflex: when a baby's head turns, the arm on that side straightens, and the other arm bends. As it fades, typically between 3 and 9 months, the head, eyes, and hands start working independently. A baby can then look at a toy and bring both hands to it, the basic coordination needed to see where something went and reach for it.
Palmar grasp reflex. Anything pressed into the palm triggers a tight grip. This usually fades by 4 to 6 months, giving way to purposeful grasping and letting go. Lifting a cloth off a hidden toy or tipping over a cup requires that kind of control.
Moro reflex. A sudden change in head position or a loud sound triggers a full-body startle, driven largely by the vestibular system, which senses balance and motion. It usually fades by 4 to 6 months as head control and posture mature. As it fades, a sudden sound no longer throws a baby's arms wide and breaks their focus, so attention can stay on where the toy went.
Symmetric tonic neck reflex (STNR). When a baby's head tips up, the arms straighten, and the legs bend. When the head tips down, the reverse happens. It appears around 6 to 9 months, helps a baby get onto hands and knees, and usually fades by 9 to 11 months so the arms and legs can move independently for crawling.
Hands and Knees
As posture steadies, babies can sit without propping themselves up, which frees their hands to explore. In a study of babies 4½ to 7½ months old, the best predictor of understanding that an object has a hidden back side was how much the baby turned the object and passed it between their hands while looking at it. Picture a baby rotating a toy truck. Each turn reveals a side that was hidden a moment ago, and over many turns, the brain learns that what it can't see is still there. It's a close cousin of object permanence, learned through the hands.
Crawling brings object permanence out into the room. As the baby moves, the toy's position relative to them keeps changing, so the note on the whiteboard has to keep updating.
In a study of 8½-month-olds, 76 percent of babies with at least nine weeks of moving on their own found the toy at Cup B, compared with 13 percent of babies who weren't yet moving. Belly crawlers did no better than babies who weren't crawling, which suggests the type of movement matters. In a small group of babies with spina bifida, who often crawl later, performance improved once they began moving, not simply with age. Experience, not just age, appears to help build the system the A-not-B task measures.
Movement, Reflexes, and Working Memory
The link between movement and thinking continues past infancy. The cerebellum, at the back of the brain, is best known for coordinating movement, but it works closely with the prefrontal cortex. Both regions often look different in ADHD and autism. A 2024 review found a small positive connection between motor skills and executive function in children and teens, though most studies measured both at the same time and can't show which affects the other.
Retained reflexes are one place researchers look for that connection. Some children still show signs of primitive reflexes past infancy. A 2026 review of 14 studies of children ages 3 to 11 without diagnosed conditions linked retained reflexes with weaker balance, coordination, and hand skills, as well as lower reading, spelling, and math scores. A 2023 analysis of 229 children with ADHD found moderate links between ADHD symptoms and the ATNR and STNR, though its authors called the evidence preliminary.
Intervention research is mixed. In one of the strongest studies, a randomized, double-blind trial found that only a specific reflex-based movement program reduced a retained ATNR in 8- to 11-year-olds with reading difficulties; general placebo movements and no movements did not. The published summary reports the reflex results but not reading results. Many other programs have no comparison group, and the field still lacks a standard test for retained reflexes.
No study has directly tested whether retained reflexes affect object permanence. If they play a role, it's most likely on the acting side: steadying the body, directing attention, and overriding automatic responses. For now, retained reflexes are best understood as one possible sign of how a child's movement and alertness systems are maturing, not a proven cause of working-memory differences. Movement and thinking grow side by side, but improving one doesn't automatically improve the other.
When the Trail Looks Different
Movement is one route into object permanence, but not the only one. A difference in the senses, the body, or the whiteboard and brake can change how and when a child shows what they know.
Visual impairment. Sight usually shows a baby where an object went and guides the hand there. Without sight, sound has to do both jobs, and it's less reliable, because a toy that goes quiet gives no sign that it still exists. In a classic study, blind babies first reached for objects at about 10 months, compared with about 5 months for sighted babies, and only when the object made a sound. Their crawling was delayed as well. Object permanence still develops, on a later timeline built from hearing and touch.
Limited self-movement. Babies with spina bifida or other movement differences have fewer chances to practice tracking objects as they themselves move, so their progress often follows the start of independent movement.
Down syndrome and other intellectual disabilities. In one study, children with Down syndrome ages 20 to 43 months most often reached the A-not-B stage that most babies pass at 8 to 12 months. Yet many could watch an action and copy it later from memory, showing more memory than the hidden-toy task captured. Testing can also be uneven, because some children avoid tasks they find hard.
Brain chemistry differences. PKU is a metabolic condition screened for at birth and managed through diet. Even with early treatment, children whose blood levels ran moderately high showed weaker working memory and inhibition, while other thinking skills stayed on track. The whiteboard and brake depend on both chemistry and structure.
Prematurity. Healthy babies born at 32 weeks or earlier could all find a toy under a single cup at 8 months corrected age (counted from the due date). With more cups and longer delays, they scored lower than full-term babies on working memory and resisting distraction. The concept was in place, but the skills for acting on it were still catching up.
Across these differences, the understanding that objects continue to exist proves remarkably sturdy. What varies is the timing and the systems for acting on it. The same is true of the lunch left in the fridge.
Correcting the ADHD Myth
People with ADHD do not lack object permanence. Your daughter knows her lunch exists. What differs is the acting side, the same split the A-not-B task revealed in babies. ADHD researchers often describe it as a difficulty doing what you know, not knowing what to do.
Three skills are involved. Two are familiar from the cups. Children with ADHD show large differences in working memory, for both words and visual-spatial information. Differences in inhibitory control make it harder to resist whatever grabs attention in the moment, such as the dog, a sibling, or a show. The third skill is prospective memory: remembering to do something at the right future moment. It turns "I need to grab my lunch, or I'll be hungry later" into actually picking it up on the way out the door.
Prospective memory is where the lunch problem lives. Remembering at the right moment usually depends on a cue, and a busy morning offers few. Once the lunch is out of sight, nothing brings the plan back to mind. A rushed or stressful morning weakens the whiteboard and brake even further. That's why visible cues work so well. A sticky note on her shoes that says "Lunch is in the fridge" brings the plan back at exactly the right moment.
The prefrontal cortex is one of the last brain regions to mature, and it keeps developing into the mid-20s, so the whiteboard and brake are still under construction in every teenager.
Autism and AuDHD
Autism research shows the same split. In a small 1981 study, all 16 autistic children ages 3 to 6 reached the highest level on hidden-object tasks, matching typically developing children at the same developmental level. Later research has located the differences in the whiteboard and the brake instead.
In a study of babies with an older autistic sibling, there were no group differences on the A-not-B task at 12 months. By 24 months, babies with an autistic sibling showed weaker working memory than babies without that family history, and those later diagnosed with autism also showed weaker inhibition. The differences emerged in the acting layer, not in the concept itself.
The earlier sections may help explain why. Motor differences are common in autism, which fits with the cerebellum-prefrontal cortex partnership. Persistent primitive reflexes have been reported in some autistic children, and many experience differences in sensory response and arousal. Under the Goldilocks pattern, an overwhelming environment could make it harder to hold information in mind, though that connection is an extrapolation, not a tested finding.
For children who are both autistic and ADHD, often called AuDHD, no research looks specifically at object permanence. Both profiles involve differences in working memory, inhibition, arousal, and movement. It's reasonable to expect those differences to add up while the core understanding stays intact, but that is also an extrapolation.
Layered Supports
Whatever a child's profile, the same four layers can be supported: the body, alertness, the whiteboard, and the brake. Support tends to work best when it reaches more than one layer.
The body: movement and exploration.
Offer plenty of floor and tummy time, the postures and movements that gradually replace early reflexes.
Give babies time to sit and handle objects freely, turning them and passing them from hand to hand.
Make room for hands-and-knees crawling, and resist rushing past it.
Keep active play going as children grow, with climbing, balancing, and coordination games.
Alertness: the Goldilocks zone.
Protect sleep. Tired brains hold less in mind.
Build predictable routines for moments that demand memory, like leaving the house.
When your child is overwhelmed, help them settle before asking them to remember or switch tasks.
The whiteboard: working memory.
Play peekaboo and hide-and-find games. They're object permanence practice in disguise.
Keep important items visible with hooks, clear bins, open shelves, and a "launch pad" by the door.
Place reminders where the action happens, like a sticky note on shoes or the front door, and use checklists, timers, and phone reminders for multistep routines.
With older kids and teens, build cues together. A system they help design, like where the sticky note goes or which phone reminder to set, is one they're more likely to use.
The brake: inhibitory control.
Play stop-and-go games like "Red Light, Green Light," "Freeze Dance," and "Simon Says."
Reduce what competes with the plan. A morning routine finished before the screen goes on asks less of the brake.
When to ask a professional. Talk with your pediatrician and ask about developmental screening if your baby:
isn't reaching for a wanted toy by about 6 months, or looking for dropped objects by about 9 months;
uses one side of the body noticeably differently from the other;
doesn't follow objects with their eyes or turn toward sounds;
loses skills they once had.
For older children, talk with your pediatrician or your child's school if forgetting and follow-through cause ongoing problems at home or school. Occupational and physical therapists can assess motor development, and a reflex integration practitioner can evaluate reflex patterns. Reflex-based work can be one layer of support alongside changes at home, school accommodations, and medical care.
Out of Sight Is Not Out of Existence
In everyday conversation, "object permanence" has become shorthand for "out of sight, out of mind," an experience many neurodivergent people describe as especially strong. The shorthand points to something real, but the science is more precise. Object permanence is one of the first big ideas a baby figures out, and it holds up remarkably well. It develops in children who are blind, children born early, autistic children, and children with ADHD. What takes longer, and varies more, is the ability to act on it.
That ability comes from a system that matures over years. The brainstem sets alertness and, at first, runs the body's reflexes. As higher brain areas learn to hold those reflexes back, deliberate movement takes over: reaching, grasping, exploring, and crawling. Through that movement, the prefrontal cortex develops its whiteboard and its brake. When any part of this system develops differently, the route changes, but the destination usually doesn't.
The teenager who leaves her lunch in the fridge hasn't forgotten it exists. Without a cue at the right moment, the note on her whiteboard fades, and a rushed morning makes that more likely. Seeing this changes the question from "Why don't you care?" to "What would help you keep this in mind?" Often the answer is simple: put it where she can see it.
Sources
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