What are Piaget’s Four Stages of Development?

piaget four stages

Every child is a unique snowflake that travels on their own journey through life. Sure, this is true, but there are undeniable developmental milestones that all of us pass through as we grow up. This is where Jean Piaget’s of the four stages of development come in.

Jean Piaget was a Swiss psychologist (1896-1980) who is most famously known for his work on child intellectual development. If you go to occupational therapy school, it’s likely that Piaget comes up very quickly in one of your intro classes.

More specifically, Piaget is known for his “four stages of development.” These stages tell us where a child should be in their development at given ages and what it should look like.

We’re going to dive into each of these four stages and give you an idea of what to expect.

Big head’s up! Piaget’s developmental stages are very well known and well regarded. That said, he was not the only psychologist doing work in this space at this time. There are other developmental theories out there that are also valuable. 

This is not to say that Piaget is right or wrong; it’s just that there is always more than one lens you can use to look at something. Piaget is a great lens, but he’s not the only one.

Another big head’s up! If you found this page because you are worried about your child’s development, stop right now and call your pediatrician. This post is purely informational and is not meant to be specific to any kiddo or situation. 

Alright, now that we have that over with, let’s talk about Piaget’s four stages of child development.

1) Sensorimotor Stage: Birth-18-24 months

The sensorimotor phase is where all babies begin when they’re born. As you can guess from the name, this stage has a lot to do with the senses. And, as with anything sensory, this makes me excited! 

Piaget’s sensorimotor phase is based on the idea that babies initially learn through their senses. Noises, movements, tastes, and smells all provide valuable information to growing babies that are just discovering the world for the first time. 

The sensorimotor stage is broken down into 6 substages that further explain the development that happens through infancy. 

1) Reflexes: 0-1 months

Reflexes are vital for survival. When a baby is born and knows how to suck on a nipple, reach for an adult, and tense up when startled, these are all reflexes that a baby needs to know in order to get their basic needs met.

Piaget's Four Stages

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2) Primary Circular Reactions: 1-4 months

At this age, babies will start repeating behaviors they find interesting or pleasurable. This is really a time of discovery and exploration. Wiggling is fun! Oooh, that noise seemed to get my mom’s attention!

3) Secondary Circular Reactions: 4-8 months

Moving on from their own bodies, babies in this stage start to involve objects in their movements. Maybe they start grabbing the rails of their crib, reaching for their teether, or banging on the floor. The key to this stage is that babies start to understand the relationship between their bodies and the objects around them.

4) Coordination of Secondary Circular Reactions: 8-12 months

This stage is when babies start to learn how to plan their movements and actually work  towards a goal. I want that toy, so I’m going to reach for it. I like the sound of clapping, so I’m going to clap. At this point, a baby’s brain is developed enough to allow for basic planning abilities.

5) Tertiary Circular Reactions: 12-18 months

You may be thinking that this is the age when mischief starts happening. Well, that’s not  by accident. During this stage, babies start to understand trial and error and start to experiment with how their actions impacts what happens next. At this stage, babies may knock over blocks, throw toys, and pull on anything in sight. While chaotic, this is an important part of their cognitive development.

6) Early Representational Thought: 18-24 months

At the end of the sensorimotor phase comes the ability for babies to understand objects as symbols. This means that babies are starting to visualize objects that aren’t there. This is a really key skill in developing object permanence, which is the ability to know that an object exists, even if you can’t see it.

In short, the sensorimotor stage is when babies begin to explore and understand the world around them. By the time they have moved on from this stage, they understand how to interact with objects, what cause and effect means, and that objects still exist even if they can’t be seen. 

2) Preoperational Stage: age 2-about 5

Facts vary about when Piaget’s second stage ends, but you can generally think that kids will move on to the third stage between the ages of 4 and 7. I know, this is a big range. But, you’ll understand why when we dive into what the preoperational stage actually is.

The preoperational stage focuses on the development of speech. While a lot of things happen between the ages of 2 and about 5ish, one of the most dramatic differences between kiddos these ages is their abilities to speak. While a 2 year old may be stringing words together, a 5 year old can tell full stories.

Yet, a child who is in the preoperational stage is lacking something very important that they will later develop in the following stages–the ability to consider multiple perspectives when thinking through a problem. In addition, the only perspective these kiddos generally consider is their own, as they can’t yet understand how to look through the lens of someone else’s.

Because children in this stage often consider only their own perspectives, they can be referred to as “egocentric.” Now, this is not the same egocentric we use to refer to self-centered adults. This egocentrism is a normal part of development. Kids in the preoperational stage are just learning how to solve problems, express their thoughts, and develop more advanced symbolic thinking. All of this is hard enough without having to worry about what’s going on in other peoples’ heads. Understanding the perspectives of others is an advanced skill, which is premature at this point.

So, the preoperational stage is when kiddos focus on their own self-mastery and develop the foundational skills they need to progress on to stage 3.

3) Concrete Operational Stage: age 7-about 11

Piaget’s third stage is when logic develops. At this age, kids are thinking in concrete ways and struggle with abstract ideas. Another key aspect of this stage is the understanding of conservation, which is the idea that if you break something up into parts, all of those parts still add up to equal the whole object. 

Progressing from the preoperational stage, kids can now use a number of different parts or perspectives to understand how to solve problems. Given that this is a new ability, kids may be experimenting with the perspectives of others and trying to understand why other people think and act the way they do.

4) Formal Operational Stage: age 12-adulthood

We’ve reached Piaget’s last developmental stage! In this fourth stage, kids progress to where they need to be as adults. Naturally, this can take varying amounts of time. 

During the formal operational stage, logic continues to develop. Specifically, deductive logic enters the picture. Deductive logic refers to the ability to understand a general principle and use that knowledge to come to a specific outcome.

Abstract thinking develops during this stage as well, which allows for problem solving hypothetical situations. 

In general, people progressing through this stage will start to think systematically, abstractly, and hypothetically, deciding which form of logic is best given the problem that needs to be solved.


Diana is a registered occupational therapist who specializes in sensory processing disorders and autism.

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