Object Permanence: Age, Piaget, Baillargeon and the Evidence

Piaget concluded that babies under about 8 months act as if a toy hidden under a cloth has stopped existing. Yet Renée Baillargeon’s experiments found signs of object permanence in babies as young as 3½ months.

Every parent has seen it. Drop a cloth over a 5-month-old’s favourite rattle and the baby looks away, as if the rattle has vanished from the universe. Do the same thing a few months later and the baby whips the cloth off, delighted. Somewhere in between, the baby has worked out one of the most basic facts about the world: things carry on existing when they are out of sight.

Psychologists call this object permanence. Jean Piaget made it a cornerstone of the first stage of his theory of cognitive development, and for decades his ages were taken as fact. Then, in the 1980s, a new kind of experiment that measured what babies looked at rather than what they reached for suggested the understanding arrives months earlier. The argument about who was right is still running, and it is one of the best examples in psychology of how the way you measure something changes the answer you get.

This guide answers the age question first, then walks through Piaget’s six stages, the famous A-not-B error, Baillargeon’s experiments and the case against them. It also covers separation anxiety, the “object permanence” idea people use about ADHD, play ideas for each age, and a free quiz to test whether you can spot each stage. If you are new to Piaget, his ideas about schemas, assimilation and accommodation are the building blocks this all rests on.

What Age Does Object Permanence Develop?

Object permanence develops gradually from birth to about 2 years old. Babies first show they expect hidden objects to still exist at around 3½ to 4½ months in looking studies (Baillargeon, 1987). They start reaching for a fully hidden toy at around 8 months, and object permanence is fully developed at around 18 to 24 months, when toddlers can find an object that was moved while out of sight (Piaget, 1954).

So there is no single “object permanence age”. There are three milestones, and which one people mean depends on how they are measuring it:

Object permanence at 6 months

Object permanence at 6 months is partial. A 6-month-old will grab a toy that is sticking out from under a blanket and will look down at the floor when a spoon is dropped from the high chair. If the toy is covered completely while the baby watches, though, most 6-month-olds stop reaching for it. In Piaget’s terms they are in substage 3, which runs from about 4 to 8 months.

Object permanence at 1 year

Object permanence at 1 year is well under way. Most 12-month-olds will search for a toy they watched being hidden, and they are beginning to follow it when it moves between hiding places. The understanding is not yet complete: a 1-year-old can still be fooled when an object is moved while they cannot see it.

Object permanence at age 2 and 3

Object permanence at age 2 is, in Piaget’s account, complete. By 18 to 24 months a toddler can hold a picture of an object in mind and reason about where it must have gone. By age 3 children are well past this milestone and are using that same ability to pretend, remember and plan. If a 3-year-old seems not to grasp that hidden things still exist, that is unusual enough to mention to a health visitor or doctor, alongside other developmental milestones.

What Is Object Permanence?

Object permanence is the understanding that objects, people and animals continue to exist even when they cannot be seen, heard, touched or otherwise sensed. A baby who has object permanence knows that the ball which rolled under the sofa is still there, and that a parent who left the room has not disappeared from existence.

The term comes from Jean Piaget, the Swiss psychologist who studied his own three children in detail and described their behaviour in The Construction of Reality in the Child (Piaget, 1954). Piaget argued that newborns live in a world of fleeting pictures and sensations. For a young baby, he thought, an object exists only while it is being looked at, sucked or held. Building the idea of a permanent object, one that has its own existence separate from the baby’s actions, takes the whole of the first two years.

In psychology definitions, object permanence is usually described as the key achievement of the sensorimotor stage, the first of Piaget’s four stages, when babies learn through their senses and movements rather than through words or symbols. It matters because it is the first sign of mental representation: the ability to hold an image of something in mind when it is not in front of you. That ability later underpins pretend play, language and memory.

Everyday examples of object permanence

• Peekaboo. The game is funny to a baby partly because your face disappears and comes back. Once babies have object permanence, they anticipate the return and start pulling the cloth away themselves.
• Searching under a blanket. A baby who lifts a blanket to find a hidden toy is showing they believe it is still there.
• Crying when a parent leaves. Protesting at a departure only makes sense if the baby knows the parent still exists somewhere else.
• Looking for a dropped toy. Watching where a toy fell, then looking for it on the floor, shows the baby expects it to still be there.
• Going to the door. A toddler who hears the doorbell and runs to the door expects someone to be on the other side.

Piaget’s Stages of Object Permanence

Piaget’s stages of object permanence are the six substages of the sensorimotor stage, from birth to about 24 months. In each one, babies search for hidden objects in a more advanced way, moving from no searching at all, to finding partly hidden toys, to fully hidden toys, and finally to working out where a toy must be when it was moved out of sight (Piaget, 1954).

Piaget’s names for the substages describe a baby’s general thinking, not only object permanence, and the ages are approximate. What mattered to him was the order, which he thought was the same for every child.

Substage 1: reflexes (0 to 1 month)

In substage 1, newborns show no object permanence at all. They respond with reflexes such as sucking and grasping, and when an object leaves their field of view they make no attempt to follow or find it. Piaget described the newborn’s world as a series of pictures that appear and vanish.

Substage 2: primary circular reactions (1 to 4 months)

In substage 2, babies keep gazing at the place where an object or person disappeared, but they do not search for it. A “circular reaction” is Piaget’s term for repeating an action because it produced an interesting result, and in this substage the actions centre on the baby’s own body, such as thumb-sucking. The lingering look at an empty doorway is, for Piaget, just the continuation of the act of looking rather than a belief that the person still exists.

Substage 3: secondary circular reactions (4 to 8 months)

In substage 3, babies will retrieve a toy that is partly hidden, but not one that is fully covered. They now repeat actions that affect the world around them, such as shaking a rattle to hear the sound. They also begin to anticipate where a falling object will land and look there. Piaget’s classic observation was that if a toy disappeared completely under a cloth while the baby was reaching for it, the baby would simply stop reaching, as if the toy no longer existed.

Substage 4: coordination of secondary schemes (8 to 12 months)

In substage 4, babies search for a fully hidden object for the first time, which is why 8 months is the age most often given for object permanence. Babies can now combine two actions to reach a goal: pushing a cushion aside (one action) in order to grab the toy (another). Their understanding is still tied to their own actions, though, and that produces the most famous mistake in infant psychology, the A-not-B error, explained in the next section.

Substage 5: tertiary circular reactions (12 to 18 months)

In substage 5, toddlers follow an object as it is moved from one hiding place to another in plain view, and search in the last place they saw it go. Piaget called these “visible displacements”. Toddlers in this substage are little scientists who vary their actions to see what happens, such as dropping things from different heights. They are still caught out by “invisible displacements”, where the object is moved while hidden, for example inside a closed hand.

Substage 6: beginnings of representational thought (18 to 24 months)

In substage 6, object permanence is fully developed: toddlers can work out where an object must be even when they did not see it moved. If you hide a coin in your fist, pass your fist under a cushion and then show an empty hand, a child in this substage will look under the cushion. Piaget saw this as proof that the child can now represent objects mentally, which opens the door to the preoperational stage, pretend play and language. You can practise putting the four main stages in order with the Piaget cognitive stages game.

The A-not-B Error Explained

The A-not-B error is the mistake babies of about 8 to 12 months make when a toy they have found several times at place A is hidden at place B in front of them, and they still search at A. Piaget described it in substage 4 and took it as evidence that the baby thinks the toy’s location depends on the baby’s own past actions, rather than on where the toy actually went (Piaget, 1954).

The task works like this. A researcher hides a toy under cloth A, and the baby finds it. This is repeated a few times. Then, with the baby watching, the researcher hides the toy under cloth B. After a short delay, many babies reach straight back to cloth A, even though they watched the toy go under B. It is a striking thing to see, because the baby clearly saw where the toy went.

Why do babies make the A-not-B error?

Babies make the A-not-B error for reasons that are still debated, and there are three main explanations:

• Memory and inhibition (Diamond). Adele Diamond tested 25 babies every two weeks from the time they first reached for a hidden object until they were 12 months old (Diamond, 1985). She argued that success needs two abilities: holding the new location in mind, and holding back the habit of reaching to A. Both depend on the prefrontal cortex, which is still maturing. This links the error to executive function and working memory.
• Movement habits (Smith and Thelen). Linda Smith, Esther Thelen and colleagues argued that the error is about the body as much as the mind. Across six experiments, they found that the reach back to A comes from the ordinary processes that guide a hand to a place: memories of previous reaches, a body-centred sense of space, and the close link between where a baby looks and where it reaches (Smith et al., 1999).
• Social misunderstanding (Topál and colleagues). József Topál and colleagues noticed that researchers hiding the toy usually smile, make eye contact and talk to the baby. Babies may read this as “this is where things go in this game”. When the toy was hidden without these communicative cues, the error rate among 10-month-olds fell from 81% to 41% (Topál et al., 2008).

These explanations are not mutually exclusive. Most researchers now think the A-not-B error tells us less about whether babies believe objects exist and more about how memory, habit and social cues compete when a baby has to act.

Baillargeon’s Object Permanence Experiments

Renée Baillargeon’s object permanence experiments showed that babies of 3½ to 5 months look longer at events in which a hidden object seems to vanish or be passed through, which suggests they expected the object to still exist. Her method, called violation of expectation, measures surprise through looking time, so it does not depend on the baby being able to reach and search.

The logic is simple. Babies, like adults, stare longer at something surprising. If a baby looks longer at an “impossible” event than at a “possible” one, the baby must have expected something different, and that expectation is evidence of what the baby knows.

The drawbridge study (Baillargeon, Spelke and Wasserman, 1985)

In the drawbridge study, 5-month-old babies first watched a screen rotate back and forth through 180 degrees, like a drawbridge, until they were bored. Then a box was placed behind the screen. In the possible event the screen rotated until it stopped against the box. In the impossible event the screen rotated through the full 180 degrees, apparently passing through the space where the box was (the box had been secretly removed). Babies looked reliably longer at the impossible event, even though it was the movement they had already seen many times (Baillargeon et al., 1985). That suggested they knew the hidden box was still there and that a solid screen should not pass through it.

Younger babies (Baillargeon, 1987)

Baillargeon then ran three experiments with younger babies using the same idea. The 4½-month-olds, and the 3½-month-olds who habituated quickly, looked reliably longer at the impossible event than at the possible one. Baillargeon concluded that these results seriously questioned Piaget’s claims about the age at which object permanence emerges (Baillargeon, 1987).

The carrot study (Baillargeon and DeVos, 1991)

In the carrot study, 3½-month-olds watched a short or a tall carrot slide behind a screen that had a window cut into its upper half. A short carrot should pass below the window unseen, and it did. A tall carrot should appear in the window as it passed, but in the impossible event it did not. Babies looked longer when the tall carrot failed to appear, suggesting they were representing the carrot’s height while it was hidden and reasoning about where it should be visible (Baillargeon and DeVos, 1991).

Reaching in the dark (Hood and Willatts, 1986)

Not all the early evidence came from looking. Bruce Hood and Peter Willatts showed 5-month-olds an object, then turned out the lights. Filmed with infrared, the babies reached towards the place where the object had been, which suggests they remembered it was there even though they could no longer see it (Hood and Willatts, 1986). Darkness removes the cloth that Piaget used, and with it the problem of having to move one thing to get another.

Baillargeon’s later work went further, arguing that babies are born with a basic expectation that objects persist and are solid, and then learn more specific rules, for example about height and containers, one event type at a time (Baillargeon, 2004).

Piaget vs Baillargeon: What Does the Evidence Show?

Piaget and Baillargeon disagree mainly about age because they measured different things. Piaget asked whether babies would search for a hidden object, which needs memory, planning and a coordinated reach. Baillargeon asked whether babies would look surprised when a hidden object behaved impossibly, which needs much less. Most psychologists now accept that young babies have some knowledge of hidden objects before they can act on it, but they argue about how rich that knowledge is.

The case against Piaget

The main criticism of Piaget is that he confused competence (what a baby knows) with performance (what a baby can do). A 6-month-old who does not lift a cloth may know the toy is under it but lack the skill to remove one thing in order to get another. Baillargeon’s looking studies and Hood and Willatts’ reaching-in-the-dark study were designed to remove that barrier, and both found signs of object permanence months earlier than Piaget’s ages. Psychologists such as Margaret Donaldson made a similar argument about Piaget’s tests of older children: change the task so that it makes sense to the child, and children can suddenly do more.

The case against Baillargeon

The main criticism of Baillargeon is that looking longer does not necessarily mean “I am surprised because I know objects persist”. Marshall Haith warned against this kind of “rich interpretation”, arguing that simpler perceptual explanations should be ruled out before crediting babies with adult-like concepts (Haith, 1998). Richard Bogartz and colleagues proposed that babies may look longer at events that are simply more novel or more familiar to them, and designed experiments to separate these effects (Bogartz et al., 1997). Rivera, Wakeley and Langer (1999) re-ran the drawbridge study and argued that 5-month-olds looked longer at the 180-degree rotation even without a box behind the screen, simply because it involved more movement.

Where the debate stands

The debate stands roughly here: babies do seem to track hidden objects well before 8 months, but that early knowledge is fragile and limited, and it takes most of the first two years to become the flexible, usable understanding Piaget described. Moore and Meltzoff (2008), for example, found that 8¾-month-olds removed a cover to get a partly hidden toy but failed to use the same skill when the toy was hidden completely, and that a sound coming from the hidden toy helped 10-month-olds but not younger babies. That fits the idea that object permanence develops piece by piece rather than switching on at one age. For parents and practitioners, Piaget’s stages are still a useful guide to what you will see; Baillargeon’s work is a reminder that babies may understand more than they can show.

Object Permanence Quiz: Which Stage Is This Baby In?

This free object permanence quiz gives you ten short descriptions of real-world baby behaviour. For each one, choose the Piaget substage it best fits. It is a learning quiz for students and practitioners, not a test of your own child’s development.

Why Is Object Permanence Important?

Object permanence is important because it is the first evidence that a baby can hold a mental picture of something that is not there. Piaget saw this ability, mental representation, as the bridge from thinking through actions to thinking with symbols, which is what makes words, pretend play and remembering the past possible (Piaget, 1954).

• Cognitive development. Holding an image in mind is the basis of memory development in early childhood, planning and problem-solving.
• Language. Words stand for things that are often not present. A child who understands that "ball" refers to a ball that still exists in the toy box has a reason to use the word.
• Pretend play. Using a block as a phone means holding the idea of a phone in mind while looking at a block, a skill that appears at the end of the sensorimotor stage.
• Relationships. Knowing that carers still exist when they leave the room is part of forming attachments, and part of why babies begin to protest when those carers go.

Object Permanence and Separation Anxiety

Object permanence and separation anxiety develop around the same time, in the second half of the first year. A baby who knows a parent still exists after leaving the room, but cannot yet predict when the parent will come back, has a good reason to protest. In Schaffer and Emerson's study of 60 Glasgow babies, specific attachments, shown by protest when a particular person left, appeared from around 7 months for most of the babies (Schaffer and Emerson, 1964). You can read more in our guide to Schaffer and Emerson's stages of attachment.

The overlap is a timing link, not proof that one causes the other. Separation anxiety is also shaped by temperament, the quality of attachment and the baby's experience of carers leaving and returning, as described in attachment theory and in Ainsworth's Strange Situation. For practitioners settling babies into a nursery, the practical point is the same: short, predictable goodbyes and reliable returns help a baby learn that people who leave come back.

Object Permanence Activities, Games and Toys

Object permanence activities are simple hide-and-find games that let babies practise the skill they are working on. The best activity depends on the baby's stage: partly hidden toys for younger babies, fully hidden toys from about 8 months, and multi-step hiding games for toddlers. None of these will speed up development, but babies enjoy them because they are working at the edge of what they can do.

Activities for babies under 8 months

• Peekaboo. Hide your face behind your hands or a cloth for a second or two. Keep the pauses short at first.
• Partly hidden toys. Tuck a favourite toy under a muslin with part of it showing, and let the baby pull it out.
• Watch it fall. Drop a soft toy slowly from the high chair tray and say "Where did it go? There it is!"

Activities for babies from 8 to 12 months

• Under the cup. Hide a toy under an upturned cup or bowl while the baby watches.
• Treasure under the blanket. Cover a toy completely and encourage the baby to find it.
• Object permanence box. This Montessori-style toy is a box with a hole in the lid and a tray at the side. The baby posts a ball through the hole, it disappears, and then it rolls out into the tray. Shape sorters and ball runs work in a similar way.

Activities for toddlers from 12 to 24 months

• Two or three cups. Hide a toy under one cup, then move it to another while the toddler watches.
• Hidden in the hand. From about 18 months, hide a small toy in your closed hand, pass your hand under a cushion and leave it there, then show your empty hand.
• Simple hide and seek. Hide behind a door or curtain, with a bit of you showing at first.
• Tidy-up games. "Where does teddy live?" encourages toddlers to remember and find things that are put away.

Open-ended resources such as treasure baskets and boxes with lids give babies plenty of chances to hide and find things for themselves. The types and stages of play guide covers how this kind of exploratory play develops.

Object Permanence and ADHD

"Object permanence" in ADHD is an informal, popular term, not a clinical one. People use it to describe an "out of sight, out of mind" pattern: forgetting about tasks, belongings or even friends when they are not in view. It does not mean adults with ADHD lack object permanence in Piaget's sense; they know perfectly well that hidden objects still exist. ADHD diagnostic criteria do not mention object permanence (American Psychiatric Association, 2013).

What people are usually describing is closer to difficulty with working memory, the mental workspace that holds information in mind while you use it. A meta-analysis of 26 studies found that children with ADHD showed deficits across several kinds of working memory, with the largest effect sizes for spatial tasks (Martinussen et al., 2005). If information is not being held in mind, things that are not visible are easier to forget, which matches the everyday experience people describe.

Object permanence in relationships

Object permanence in relationships is another informal use of the term. People with ADHD sometimes say they do not think to message friends they are not seeing, or that they "forget" people in long-distance relationships. This is about attention and memory, not about caring less. Practical strategies that people find helpful include keeping things visible (clear storage, notes, photos), setting reminders to contact people, and explaining the pattern to friends and partners. If ADHD is suspected, a proper assessment comes from a qualified professional; see our overview of ADHD, autism and dyslexia for how these conditions differ.

Object Permanence vs Object Constancy

Object permanence and object constancy are often confused, but they come from different theories. Object permanence is Piaget's cognitive idea: knowing a physical object exists when you cannot see it. Object constancy comes from psychoanalytic theory, especially Margaret Mahler and her colleagues, and refers to keeping a stable, emotional sense of a carer, including both their good and frustrating sides, when they are absent (Mahler et al., 1975).

A baby needs object permanence before object constancy is possible: you cannot hold a steady feeling about someone who, as far as you know, has stopped existing. Object constancy is closer to Bowlby's idea of an internal working model, a mental picture of relationships built from early experience.

Do Animals Have Object Permanence?

Many animals have object permanence, and researchers have tested them with versions of Piaget's hiding tasks. Dogs are one of the best-studied examples. In tests with several breeds of adult dogs, Gagnon and Doré (1992) found that dogs solved invisible displacement problems, the substage 6 task, although they were less successful on these than on visible displacements. When smells were masked, the dogs still performed in the same way, suggesting they were using a mental representation of what they had seen rather than following their noses.

So yes, dogs have object permanence: your dog knows you still exist when you leave for work. Whether a dog understands when you will be back is a different question, and one the hiding tasks do not answer.

How to Cite Piaget's Object Permanence

Piaget's object permanence is usually cited as Piaget (1954), the year the English translation of The Construction of Reality in the Child was published in the United States. The original French book, La construction du réel chez l'enfant, appeared in 1937. In APA 7, cite the edition you used and, if you want to show the original date, write it as (Piaget, 1937/1954).

A reference list entry for the 1954 translation looks like this: Piaget, J. (1954). The construction of reality in the child (M. Cook, Trans.). Basic Books. For Baillargeon, the most cited object permanence papers are Baillargeon, Spelke and Wasserman (1985) for the drawbridge study and Baillargeon (1987) for the younger infants; all are in the reference list below.

Conclusion

Object permanence is the understanding that things still exist when they are out of sight. Piaget traced it through six substages, with babies searching for a fully hidden toy at around 8 months and mastering hidden moves by 18 to 24 months. Baillargeon's looking-time experiments suggest babies have some sense of hidden objects from about 3½ months, though critics argue those studies may be measuring simpler perceptual reactions. Both views agree on the direction of travel: from a world of disappearing pictures to one of lasting objects, people and relationships.

For anyone working with babies, the practical message is simple. Hide-and-find play, peekaboo and calm, predictable goodbyes all give babies the chance to practise this new understanding, at whatever stage they are at. The sociocultural view of Vygotsky adds that the adult playing the game matters too.

Frequently Asked Questions

At what age is object permanence fully developed?

Object permanence is fully developed at around 18 to 24 months, according to Piaget. That is when toddlers can find an object that was moved while hidden, which shows they can picture it in their mind. Earlier forms appear from about 4 months, but these are partial.

Which stage of Piaget's theory is object permanence in?

Object permanence belongs to the sensorimotor stage, the first of Piaget's four stages, which lasts from birth to about 2 years. It is the main achievement of that stage and develops across all six of its substages. By the preoperational stage, from about age 2, children already have it.

What is an example of object permanence?

A classic example is a 9-month-old lifting a blanket to find a toy they saw being hidden. Others include a baby pulling a cloth off your face during peekaboo, or a toddler checking the toy box for a ball that was put away earlier. Each one shows the child expects the hidden thing to be there.

How do you test object permanence in babies?

1. Show the baby an attractive toy and let them reach for it.
2. While they watch, cover the toy completely with a cloth or cup.
3. See whether they remove the cover to find it. Searching suggests object permanence; looking away suggests it is not yet there.
4. For older babies, move the toy between two covers to check for the A-not-B error.

Is object permanence a symptom of autism?

No. A lack of object permanence is not a symptom of autism, and it is not part of the diagnostic criteria, which focus on social communication and restricted or repetitive behaviours (American Psychiatric Association, 2013). Autistic children develop object permanence. If a child shows little interest in hidden things at an age when peers do, it is worth raising with a health professional for a general developmental check.

Does object permanence apply to people?

Yes. Object permanence covers people as well as things, and Bell (1970) found that most babies grasped the permanence of people before the permanence of objects. When a baby cries as a parent leaves, they are showing they know the parent still exists, which is why object permanence is linked to separation anxiety.

Is object permanence innate?

This is the heart of the Piaget and Baillargeon debate. Piaget believed object permanence is constructed slowly through the baby's own actions. Baillargeon argues that babies start life with a basic expectation that objects persist, which experience then refines. The evidence shows early sensitivity to hidden objects, but not whether it is present at birth.

When does object permanence go away?

Object permanence does not go away once it develops. It stays for life. What changes is the behaviour around it: separation anxiety usually fades during the toddler and preschool years as children learn that people come back. Adults who describe "losing" object permanence, often in relation to ADHD, are using the term informally to mean forgetting what is out of view.

Do dogs have object permanence?

Yes. Adult dogs pass the hardest of Piaget's hiding tasks, finding an object that was moved while hidden, though they do better on easier visible moves. Experiments that masked smells showed dogs were relying on what they had seen rather than their sense of smell (Gagnon and Doré, 1992).

References

• American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). American Psychiatric Publishing.
• Baillargeon, R. (1987). Object permanence in 3½- and 4½-month-old infants. Developmental Psychology, 23(5), 655-664.
• Baillargeon, R. (2004). Infants' physical world. Current Directions in Psychological Science, 13(3), 89-94.
• Baillargeon, R., and DeVos, J. (1991). Object permanence in young infants: Further evidence. Child Development, 62(6), 1227-1246.
• Baillargeon, R., Spelke, E. S., and Wasserman, S. (1985). Object permanence in five-month-old infants. Cognition, 20(3), 191-208.
• Bell, S. M. (1970). The development of the concept of object as related to infant-mother attachment. Child Development, 41(2), 291-311.
• Bogartz, R. S., Shinskey, J. L., and Speaker, C. J. (1997). Interpreting infant looking: The event set × event set design. Developmental Psychology, 33(3), 408-422.
• Diamond, A. (1985). Development of the ability to use recall to guide action, as indicated by infants' performance on AB. Child Development, 56(4), 868-883.
• Gagnon, S., and Doré, F. Y. (1992). Search behavior in various breeds of adult dogs (Canis familiaris): Object permanence and olfactory cues. Journal of Comparative Psychology, 106(1), 58-68.
• Haith, M. M. (1998). Who put the cog in infant cognition? Is rich interpretation too costly? Infant Behavior and Development, 21(2), 167-179.
• Hood, B., and Willatts, P. (1986). Reaching in the dark to an object's remembered position: Evidence for object permanence in 5-month-old infants. British Journal of Developmental Psychology, 4(1), 57-65.
• Mahler, M. S., Pine, F., and Bergman, A. (1975). The psychological birth of the human infant: Symbiosis and individuation. Basic Books.
• Martinussen, R., Hayden, J., Hogg-Johnson, S., and Tannock, R. (2005). A meta-analysis of working memory impairments in children with attention-deficit/hyperactivity disorder. Journal of the American Academy of Child and Adolescent Psychiatry, 44(4), 377-384.
• Moore, M. K., and Meltzoff, A. N. (2008). Factors affecting infants' manual search for occluded objects and the genesis of object permanence. Infant Behavior and Development, 31(2), 168-180.
• Piaget, J. (1954). The construction of reality in the child (M. Cook, Trans.). Basic Books. (Original work published 1937)
• Rivera, S. M., Wakeley, A., and Langer, J. (1999). The drawbridge phenomenon: Representational reasoning or perceptual preference? Developmental Psychology, 35(2), 427-435.
• Schaffer, H. R., and Emerson, P. E. (1964). The development of social attachments in infancy. Monographs of the Society for Research in Child Development, 29(3), 1-77.
• Smith, L. B., Thelen, E., Titzer, R., and McLin, D. (1999). Knowing in the context of acting: The task dynamics of the A-not-B error. Psychological Review, 106(2), 235-260.
• Topál, J., Gergely, G., Miklósi, Á., Erdőhegyi, Á., and Csibra, G. (2008). Infants' perseverative search errors are induced by pragmatic misinterpretation. Science, 321(5897), 1831-1834.

Further Reading and Research

Recommended Articles

• Piaget's Theory of Cognitive Development
• Attention Span Development
• The Still Face Experiment

Suggested Books

• Piaget, J. (1954). The Construction of Reality in the Child. Basic Books.
  • The original account of object permanence, built on Piaget's observations of his own three children, with the six substages described in detail.
• Gopnik, A., Meltzoff, A. N., and Kuhl, P. K. (2000). How Babies Think. Weidenfeld and Nicolson.
  • A readable tour of modern infant research, including what looking-time studies reveal about babies' understanding of objects.
• Eliot, L. (1999). What's Going On in There? Bantam Books.
  • A neuroscientist's guide to how the brain and mind develop in the first five years, with chapters on memory and early thinking.

Recommended Websites

• PubMed: Topál et al. (2008) on the A-not-B error
  • The abstract of the study showing that communicative cues roughly double the A-not-B error rate, with links to the full paper and later comment.
• Center on the Developing Child, Harvard University
  • Short guides and videos on executive function and working memory in early childhood, the abilities behind success on hiding tasks.
• Encyclopaedia Britannica: Object permanence
  • A concise encyclopaedia definition of object permanence and its place in Piaget's sensorimotor stage.

Kathy Brodie

Kathy Brodie is an Early Years Professional, Trainer and Author of multiple books on Early Years Education and Child Development. She is the founder of Early Years TV and the Early Years Summit.

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To cite this article please use:

Early Years TV Object Permanence: Age, Piaget, Baillargeon and the Evidence. Available at: https://www.earlyyears.tv/object-permanence/ (Accessed: 7 November 2026).