The sensorimotor stage of cognitive development is the first of four phases as defined by Jean Piaget, the well-known and much revered Swiss developmental psychologist, whose work focused on the characteristics and evolution of intelligence in a human being as well as the acquisition of knowledge.

Defying the firmly established misconception, he claimed that children aren’t just smaller versions of adults nor less intelligent but that they solely perceive the environment and think in a different way than adults do.

After realizing that children at different ages make different mistakes related to problem-solving, he inferred that from birth to adulthood they all go through four stages of cognitive development as the outcome of maturation, the influence of both their physical and social surroundings and, lastly, and for Piaget most importantly, their own actions and experience.

According to his theory, every child passes through each of the qualitatively disparate stages in the same order although not at an equal speed.

This progressive development entails forming ideas, so-called schemas, which virtually serve to organize the imbibed information so that the child would comprehend the surrounding world through that preformed mold.

The cognition takes place through three processes – assimilation, namely fitting the newly absorbed information to the mold, and accommodation, viz. altering the mold in order to make it fit the previously unknown – and balancing the two mechanisms dubbed equilibration.

Understanding children’s intellectual growth can be helpful to both parents and teachers – the former can not only empathize with their kids better but also learn how to stoke their development whereas the latter can get insight in what kind of curriculum and which approach is the most suitable for students of a certain age.


From the moment of coming to this world up to the age of two, i.e. the beginning of active use of language, children are in this initial phase of their cognitive development.

Getting to know the strange place at which they arrived from their mothers’ comfy bellies is based on perception through five basic senses and physical activity reflected in the movements of their own bodies and manipulation of objects – as it can be deduced from the very name of the stage.

At the outset of this phase, infants are egocentric and regard the world as a part of their bodies – they are only aware of what is currently surrounding them, don’t comprehend causality and cannot view the world from aspect other than their own.

Hence, throughout this stage, children have to explore the world by means of trial-and-error examining the relationship between themselves and the environment in order to find the missing pieces of the puzzle!

The most significant breakthrough children achieve at the end of this chapter of their book of growth is object permanence, i.e. understanding of the continuation of the existence of objects even after they become inaccessible to the perception of the senses.

We intentionally won’t explain this concept in detail here because one of the following chapters will elaborate it thoroughly.

With all these facts in mind, parents can finally start deeming their children’s behavior such as putting toys into the mouth and throwing them around perfectly normal and, what’s more, of paramount importance for their cognitive development!


Within this stage, Piaget differentiates six sub-stages with their specific qualities, again displayed at a certain age.

1. Reflexes

This phase lasts from birth until the baby is one month old.

During this stage, the infant gets to know the world by responding to external stimuli reflexively without any signs of comprehension and with the purpose of mere survival.

So, the baby’s main actions at this point are crying, sucking objects, looking at them and following their movement with the eyes, listening to sounds and palmar grasp, namely a reflexive grip of the child’s hand when something touches the palm.

Therefore, let your child stick his or her feet in the mouth because that is how they are getting to know themselves – maybe they’ll leave a bad taste so they won’t try it again!

2. Primary Circular Reactions

The period from the first to the fourth month is marked by the formation of schemas, a fundamental part of primary circular reactions which are, in fact, intentional repetition of enjoyable actions, involving the child’s body or the nearest area around it, which previously occurred accidentally.

This means a baby will unintentionally suck his or her thumb and then repeat that pleasurable action deliberately.

The emergence of schemas which are being perfected and enriched through repetition represents the process of reproductive assimilation.

This stage also sees the creation of habits, says Piaget, reflected in the motor activities that aren’t reflexive responses.

These so-called habits open a brave new world of cognition and the ability to opt for the appropriate reaction to a stimulus.

At this age, children can even combine different schemas while performing certain actions – for example, coordinating hand movement and sucking. Talk about multitasking!

Both classical and operant conditionings become possible at this stage.

The best illustration of the former are the famous experiments of Ivan Pavlov with a dog and represents a learning process (in Pavlov’s experiments – the excretion of saliva on the sound of the bell) based on the pairing of a biological stimulus and a neutral one (in Pavlov’s experiments – the food given and the bell that precedes it).

When it comes to the latter, learning is brought about by encouraging or punishing a certain behavior.

Considering these developmental achievements – upbringing can begin! Although the infamous sentence “You’re grounded!” doesn’t have any effect yet!

3. Secondary Circular Reactions

Whereas children are preoccupied with themselves during the previous two stages, from the fourth to the eighth month, they switch their focus from their own bodies to objects in their surroundings.

Ergo, they now start intentionally repeating actions involving their environment (toys, other people) that they’ve discovered to cause agreeable results.

In order to make that happen, their coordination between vision and prehensility (the act of gripping) develops even further consequently enabling them to grasp an object on purpose.

Furthermore, besides reproductive assimilation developed in the previous phase through which schemas are fixed by repetition, we can notice the appearance of recognitive assimilation or the ability to choose the appropriate schema, as well as generalizing assimilation or the ability to apply the formed schema to a new situation.

In other words, a child that has shaken a rattle by accident hearing the amusing sound can now manipulate a stick and select the right move to hit a suspended rattle again thus making use of schemas shaped before, just in a different situation – here, we can clearly distinguish all three types of assimilation, respectively.

With the application of old schemas to new situations comes the process of accommodation too.

Still, it’s important to know that secondary circular reactions aren’t goal-directed but pop up as the child explores the world through random actions (inadvertently hitting the rattle).

Nonetheless, they obviously begin getting the hang of the difference between means and results at this point. In contrast to the previous phases, children who have reached this stage search for the objects that have disappeared from their view or are partially hidden and know where to find the ones which they have previously abandoned if they are within the range of their eyesight.

On the flip side, they are still not skillful enough to find the completely hidden ones.

Well, their fight for independence starts here! Begin coming to terms with that so that they wouldn’t catch you by surprise later on!

4. Coordination of Reactions

During this period lasting from the eighth to the twelfth month, children’s intentionality strengthens as their behavior becomes goal-oriented, meaning that they are now able to combine schemas and devise a strategy leading to the materialization of their objective.

The goal is now in focus, not the means.

So, if you conceal a toy under a blanket, they will uncover and then grasp it – this is a typical combination of schemas used to attain a goal.

Apart from that, they start being conscious of the distinguishable features of specific objects and recognizing them as such – this is called object recognition and it represents the basis for the development of object permanence.

For example, they will come to the realization that shaking makes a rattle produce the characteristic sound or that round objects can roll over.

These games that indicate the child’s understanding of the object’s use are actually the simplest form of symbolic play, a breakthrough from which pretend play originates, a version of playing that we’ll expand on in the corresponding phase.

If a perceived object gets taken away and isn’t within their sight anymore, they look for it, even if it is completely hidden, although they continue to make A-not-B error – this behavior indicates the dawn of object permanence.

Being more concentrated on the target than the mechanism of accomplishing the aim, children cease repeating actions discovered by chance to establish schemas as they did in the preceding phases; instead, they begin using them purposefully – and that’s how mobile schemas come to existence.

This means that a child will utter sounds (an already generated schema) to stay in touch with the parent who is out of sight (the newly gained object permanence).

These mobile schemas deliver prediction – based on specific signs, the child can become able to predict the ensuing event.

For instance, a noise causes a reaction of the child because he or she is aware it signifies that the parent is approaching. In relation to objects, children start displaying interest in novelties and unknown which sparks curiosity. They are even able to imitate the behavior of others.

Taking all these accomplishments into account, it’s no wonder that Piaget considered this stage to give birth to the first actual intelligence! Children can now really get it – both motion-wise and cognition-wise!

a. Object Permanence

Up until this fourth stage, infants can be entertained by the game of peek-a-boo – because they lack the comprehension of object permanence. This term refers to the child’s understanding that objects continue to exist although they are currently out of reach of senses.

The disappearance of an object can upset and its reappearance can surprise a young child because they cannot comprehend that the object didn’t completely vanish when it was hidden. Kids first need to form the aforesaid schemas, mental representations, of those things in order to become aware of their consistent existence.

Piaget came to this conclusion by hiding a toy under a blanket with the child watching and then observing whether or not he or she will look for it. In his experiments, children younger than eight months didn’t show interest in locating the hidden object.

Mehler and Dupoux suggested that this can alternatively mean that the child was just no longer interested in the toy or that a distraction had shifted his or her attention. It is also possible that the child lacked the motor skills necessary to regain possession of the object.

Therefore, some studies that followed examined how the child reacted to what he or she saw rather than what they reached for.

Bower and Wishart have carried out similar experiments with infants aged from one to four months but they used the technique of switching off the lights right after the child reached for the object.

Using an infrared camera, they recorded children repeating their attempts to find the object up to 90 seconds in the dark which could imply the existence of object permanence in much younger children than Piaget assumed.

Of course, there are critics of this theory too. Many claimed that the discovery could have been made unwittingly within the given timeframe of three minutes, presumably especially due to the unsettling dark caused by switched lights.

There is another study that challenges Piaget’s theory, specifically the part related to the age when children come to understand object permanence – the “violation of expectation” research done by Renee Baillargeon.

Firstly, six-and-a-half-month-olds were habituated to a situation – a toy car that was moving down a slanting track, becoming invisible behind a screen, then reappearing on the other side.

Secondly, the children were faced with a “possible event” – the screen was lifted to let the children see a box placed behind the tracks, and then lowered back again to partially block the view of the rolling car, right in front of the box. The car passed unhindered which didn’t take children aback.

Lastly, there came the “impossible event” – the screen was raised once again for the children to see the box situated on the tracks. As the screen was dropped, the box was secretly removed from the tracks and the car passed by the former unstopped by the latter, i.e. like going through the box.

Astonishingly, the children were looking at the “impossible event” much longer than the “possible” one indirectly manifesting surprise as a consequence of the existence of a mental representation of the box in their minds.

In another study of hers, involving 3 ½ and 4 ½-month-olds, a screen was rotating by 180 degrees. After being habituated to that event, they saw a “possible” one in which a box obstructed the rotation and then an “impossible” one showing the screen rotating through 180 degrees again, unstopped by the box.

The children reacted the same as 6 ½-month-olds in the previous study. The understanding of object permanence is extremely important because it is the overture to symbolic thinking crucial for the subsequent development of language, exploration, pretend play and the understanding of separate selves.

Nevertheless, it can also cause, for parents pretty distressing, separation anxiety.

b. Separation Anxiety

This is a normal phase in children’s development during which they find it hard to accept separation from their parents so outbursts of cry and clinging to mommies and daddies that follow every goodbye characterize this period.

Younger kids who haven’t gotten their sense of object permanence developed won’t mind if you leave them with another person.

However, the ones who attained the understanding of this concept are aware that parents still exist even though they have exited the room so – they want them back and they want it NOW!

Separation anxiety can manifest itself even later in life, between the ages of 18 months and two and a half years, whereas some kids never go through it.

There are also various stressful situations which can spur the development of this condition such as a new caretaker, sibling or home, as well as family conflicts.

In this case, it is important that you stick to your plans despite feeling guilty for leaving your child; otherwise, the child will use the same tactics to make you stay with him or her.

So as to mitigate the effects, pay attention to depart when your little “tick” is satiated when it comes to both food and sleep; leave him or her with a familiar person with whom he or she has already spent some time alone before; be determined when you say goodbye, tell your child when you’ll be back and make sure you do come back at that time to build confidence and trust.

Remember – never return after hearing your little screamer’s outcry because that will only exacerbate the situation!

c. A-not-B Error

This is a typical mistake made by children at this stage, usually overcome during the next one.

In an experiment, the baby sees the researcher hide an interesting toy under the blanket “A” and he or she quickly recovers it because of the defined notion of object permanence. This is repeated several times.

However, if the researcher hides the same toy in front of the child’s very eyes under the blanket “B” afterward, the child will succumb to the “perseveration error” which means that he or she will pick up the blanket “A” although they are both within reach and it has been clearly seen where the toy was placed.

Researchers explain this phenomenon as a child’s inclination to search for the object where he or she last saw it which proves the lack of reasoning skills.

Others claim that looking for the object under the blanket “A” is reinforced through repeated actions ending in successful discoveries and thus leading to this mistake. Yet, this leaves the undeniable fact of the vanishing of this error at an older age unexplained.

Smith and Thelen performed the same experiment but varied the postures of children and waiting time eventually determining that those factors can actually be decisive for success in 10-month-olds.

5. Tertiary Circular Reactions

From the point when they turn one until they are 18 months old, children are “young scientists”, as Piaget would say.

They perform experiments using the trial-and-error method trying to figure out new means to accomplish their aims and unfamiliar properties of objects as a result of previously emerged curiosity.

To illustrate – the child might utter various sounds or carry out diverse actions just to determine what attracts the attention of the parent or experiment with dropping a ball from different heights to see what happens.

Regarding object permanence, children don’t make the A-not-B error anymore and are capable of locating hidden objects within sight but not yet able to determine the location of the ones out of view.

So brace yourself to have your house turned into a laboratory!

6. Early Representational Thought

In this final sub-stage of the sensorimotor phase lasting from the 18th to the 24th months, the process of the formation of symbols representing events or objects is ongoing.

This is when they make the transition from apprehending the world through mere senses and actions to grasping it via metal operations and representations.

Problem-solving, insight and creativity both stem from this phase of a child’s development and object permanence becomes fully developed. A child at this age is able to view the problem on a mental plain, pick an effective solution and apply it in reality.

Let’s say a child leans against a tabouret which starts to move.

Upon realizing the problem (he or she might fall), the child secures the tabouret by placing it next to an ottoman firmly and then confidently leans against it again.

After solving the conundrum in the mind, the child conveyed the thought-out plan to the real world and materialized it.

At this point, children no longer make the A-not-B mistake and they can deduce where the toy may be even if the hiding process was unseen.

For instance, if the ball rolls under the table, they can assess the course and search for the ball at its predicted destination.

No more stashing candy, mom and dad! If your little detectives see nothing more than you heading to the kitchen with hands full of sweets, the latter’s days are numbered!

a. Pretend Play

Pretend play is a term referring to a type of play in which a toddler uses one object to represent another by assigning roles.

In the period between 9 and 17 months of age, children get to the first base with the development of their ability of pretend play through symbolic play – learning to pair things (for example, a spoon and a bowl, a comb and hair) and use them appropriately (drink imaginary tea from play teacups). And with object permanence comes memory.

When all these conditions are fulfilled, pretend play arises!

So, children at this age entertain themselves by holding fictional tea parties and “cooking” using toys, talking on a block or a banana as a phone; imitating adults by feeding a doll, etc.

It is worthy of noting that this game remains solitary until the age of three when they start giving out roles to others too.

The benefits of pretend play are manifold.

Firstly, it develops children’s cognitive skills since it involves inventing scenarios and resolving made-up issues.

Secondly, it nourishes their social-emotional skills through imitation of adults, enacting specific roles and interaction with dolls (hugging, rocking, and kissing). Next, their motor skills get refined as they handle toys and engage in more physical activity.

Last but not least, this kind of play is of monumental importance for the development of their language skills since every language system rests on symbols which represent sounds and words that stand for actual objects, feelings, events and the like. Additionally, they get a chance to practice using words suitable for a particular situation.

Therefore, provide your child with anthropomorphic toys that can serve as babies, boxes of various shapes and sizes to represent different household objects and even your own clothes to help them fully get into the role!


Just like plants need water, soil and sunlight – children need their parents’ support to thrive!

Parents can be of great help to their children during this stage, backing them up in multiple aspects!

To develop their ability to distinguish different sensations, let them touch a cold and then a warm object. Moreover, to make them perceive different items as being unlike, expose them to similar toys of dissimilar sizes or colors.

And lastly – pay attention, you coddlers – stop incessantly holding your babies into your arms!

They need freedom to research the world employing motor skills, even primitive ones such as crawling, rolling or wiggling. Leave them alone – just make sure the environment is safe!


As you were able to see, the sensorimotor stage of cognitive development is the time of grand, utterly transformative transitions.

The child metamorphoses from a mere observer of the world to which he or she solely instinctively reacts, to a genuine person, in the full sense of that word, who can not only respond befittingly via adequate moves to outer stimuli and is well-aware of all the happenings in the surrounding world, but is able, as well as ready and willing, to engagingly act on problems that come up, fearlessly venture to try everything out and learn from mistakes.

Throughout this process, you, parents, shouldn’t lose your patience and get frustrated – kids are not trying to infuriate you by repeating actions nor are they less clever because they make wrong choices!

Repetition is the mother of retention and if you don’t make mistakes, you don’t make anything!

In conclusion – your biggest contribution to your children’s development will be to expose them to as many different challenging situations as possible, leave them to deal with the latter alone and intervene only to give them helpful hints when they get stuck!

The Sensorimotor Stage of Cognitive Development

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