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Stages in Cognitive Development

Stages in Cognitive Development

As Rich Pollett’s post illustrates with these gifs of super cute kids, young children are still developing how they understand the world around them. Importantly, not only do they gain more knowledge as they grow, they also change fundamentally in how they use it. Psychologist Jean Piaget (1896–1980) proposed four stages of development as follows: 

the sensorimotor stage, from birth to age 2;

the preoperational stage, from age 2 to about age 7;

the concrete operational stage, from age 7 to 11;

and the formal operational stage, which begins in adolescence and spans into adulthood.

Originally shared by Rich Pollett

Piaget’s theory of cognitive development

These adorable children undergoing this psychological testing aren’t quite in the “Concrete Operational” stage yet.

Piaget’s theory of cognitive development:


Join the Conversation


  1. I support Piaget’s theory, and used it as support in dozens of papers, but I am still not convinced about the ages. He said he wasn’t sure either, and altered them at one point. I believe in the stages of development, but I also believe they overlap and are not restrictive i.e. if the conditions are right a child can learn something beyond their current stage of development.


  2. Brian Holt Hawthorne it’s a trade-off between gifs and videos. On my speedy wifi at home, the gifs run smoothly and instantly. A video represents a larger commitment in that many will be too lazy to play it. In such cases, the gifs capture one’s attention instantly and consistently get more engagement than a video. However, I can see how gifs are annoying if the internet connection is slow, though. 


  3. Curtis Edwards this is not my field of study, but your point about age ranges being only approximate makes sense. There must be quite a variation in cognitive development at younger ages.

    Bill Carter , I was thinking it would be fun to run some of these tests by Ms. Z and see how she responds 🙂


  4. Rajini Rao On my 1.5Mbit DSL WiFi at home, these GIFs basically never load, no matter how long I wait. Now, that might be a bug in the iOS Google+ app. I basically skip over animated GIFs because they are too slow to load, whereas I know that videos will immediately start playing when I tap them.

    So, your intuition about the trade off may not be correct for those of us who are stuck out in the Slow Zone.


  5. Rajini Rao It must be nice living in a civilized place with decent connectivity. I can’t wait until we get our municipal fiber network done. Until then, I am thrilled to have even 1.4MBps (what I actually get) when nobody else in the house is using it.


  6. It’s not a matter of fast/slow or big/small or even whether or not it’s a GIF. 6 MB image files are idiotic. I could post a 12 MB static image and that would be idiotic. If you’re going to post something that’s more than a couple hundred Kb, then link to it.


  7. Brian Holt Hawthorne I linked to the video on YouTube in my comments above, for anyone interested. The G+ platform is well known (and beloved) for the ability to host gifs and large images, and it is somewhat astonishing to hear all the complaints, to be honest. My most popular science outreach posts use gifs. Personally,  if I don’t like/have patience to read a post, I move right along!

    Rich Pollett ‘s post that we have shared here is a famous demo on cognitive development: a peek into a well-known theory of developmental psychology. Piaget’s work was new to me and it was fun to think about his ideas. This particular example illustrates “lack of conservation”. According to the Wiki article on this topic, “conservation itself is defined as: the ability to keep in mind what stays the same and what changes in an object after it has changed aesthetically. One who can conserve is able to reverse the transformation mentally and understand compensation”.


  8. Rajini Rao Fortunately, I wasn’t using Google+ over a cellular connection when that post came up or it would have eaten up a significant amount of my monthly data alotment. It is not about skipping over posts, but about posting a huge image which Google+ will automatically download without me realizing it, while I read the nice text, which is what I come to Google+ for. Those of us in third-world countries like the USA have to pay obscene amounts for Internet bandwidth, when we have it available at all.

    As much as I loved these posts, I just can’t run the risk of having another one popup while I am on my cellular plan.


  9. Brian Holt Hawthorne that’s a risk we all take at any website or email we choose to download. It’s not the responsibility of the Science on Google+ page to take into account individual connections. As I said, it’s a trade off between using gifs that may be large versus links that require a commitment to click. Overwhelmingly more people respond and engage with gifs (even silly cat gifs) than with links. Notice that our posts always provide links as well so you can navigate to them before your image fully downloads. For many, 6 MB image/gif is not a challenging size. 


  10. Yes, and I’m voting with my feet and taking responsibility by leaving. If posting videos packed into a single file that a browser may or may not play for you increases your engagement, by all means, do it. I’ll be outside that trend. I generally find items that “engage” me annoying. It’s equivalent to boosting the volume on ads and voiceovers in ads that literally shout at their audience. Good luck with that strategy.


  11. Thanks for voicing your opinion, Daniel Norton . The science community is here to discuss science. I have been trying to get the discussion back on track for some time. Consider the topic of internet speed closed in this thread. Moderator’s Comment: Off topics comments will be deleted from this point on. 


  12. Curtis Edwards – There is a lot of variability in ages and Piaget is often criticized for underestimated children’s competence. For example, according to Piaget, it is not until 8-months that babies understand that things continue to exist when they disappear (object permanence). He based this on the finding that babies before 8-months do not reach for a hidden object. However, in more recent studies conducted by Renee Baillargeon and others (e.g.,, this research shows that infants obtain object permanence earlier than proposed by Piaget. These recent studies examine infants’ looking times (they look longer to unexpected events) rather than relying on more sophisticated behaviors such as reaching. Piaget also underestimated children’s abilities to use symbols (the understanding that one object can stand for another object). Judy DeLoache and others (e.g., have shown that infants and young children can appreciate and use symbols. At the same time, some adults never reach formal operations and many of us rarely use hypothetical-analytical thought throughout the day (we primarily use heuristics and quick approximations). I believe Piaget was right; however, when proposing the idea that knowledge is built off of earlier stages. It would be impossible to understand  and use symbols (preoperational stage) if one did not already have the ability to mentally represent objects in the environment (sensorimotor stage).


  13. Rajini Rao My apologies for the meta discussion. Thanks for posting the link to the video. I have always had an issue with this Piaget study and similar studies, where the researchers are clearly speaking differently than their subjects. I don’t see this as a lack of conservation, but rather that the children understand something completely different in the words that the researchers are using.

    In the video, three scenes are presented. In the first, the subject is shown two equal size and shape glasses of liquid and agrees that they are the same. Then, one glass is poured into a tall thin vessel, and the researcher asks if one has more than the other or if they are the same. By “more”, the researchers intends to ask “which has a greater volume of liquid.” The subject interprets “more” in the terms she has learned since first speaking. Taller people are bigger and older. “More” is not a term for comparing volumes, but rather for comparing sizes. So clearly, the tall thin vessel has more than the short, squat vessel. Piaget says this is a lack of understanding the concept of conservation. Any child will tell you that the researcher is speaking a different language.

    The second scene is similar, with two identical rows of quarters being the “same”. When one row is spread out to take up more space, the subject correctly reports that that row now has “more.” In her ideolect, “more” primarily refers to spatial extent, not volume, and certainly not number. Note that when the two rows had the same spatial extent, the subject applies a secondary meaning of more, that of quantity, and counts the two rows to ensure the are truly the same. Once one row is spread out spatially, however, it is obviously more in spatial extent and the subject no longer needs to count them to apply the secondary meaning of the term.

    The final scene with the graham crackers is interesting in that we finally see the subject using number. However, the researcher now drops the use of the term “more” and wants to know whether or not the division is “fair.” Any parent of a child this age will know that if you asked the child, which of these piles would you rather have they will take the one with two whole graham crackers, rather than the one with two half graham crackers, assuming the child likes graham crackers. Children clearly understand quantity of snacks. However, the researcher neither asks the child which pile has more, nor which they would prefer, but whether the division is fair. From an early age, we drill into children that when sharing sweets or treats among siblings or friends, it does not matter whether the pieces are of identical size. Bert and Ernie from Sesame Street have perhaps the classic take on the cake division problem. So, when shown two piles of graham crackers, one containing two small pieces and one containing two large pieces, and asked by an adult authority figure whether this is fair, the child looks at the piles, looks at the adult, and declares, yes, this is fair, proud that she has seen through the adults attempt to shame her for being greedy for the two larger pieces.

    As a former student of psycholinguistics and a parent of now grown children, I have to wonder whether the people designing these studies have any clue about children and language whatsoever.


  14. Brian Holt Hawthorne  that’s a fair criticism- it’s not clear if the children simply interpreted the words differently. Hopefully, current tests take into account the ambiguities of language and its interpretation by children.  Perhaps the answers given by the test children changed as they grew older, leading Piaget to propose a progression of development.

    We consistently underestimate children! As Chris Robinson mentioned, more recent studies where eye movements are tracked, reveal even infants to be capable of more than we ever thought. 

    Psycholinguistics sounds like a very interesting topic. I’m going to have to look that up. 


  15. Brian Holt Hawthorne – Conservation errors are very well documented. I don’t share your your concern about using the word “more” (kids have no trouble understanding “more” and many younger children don’t know “volume”). Furthermore, there are studies that show these errors without using “more”. Here is some anecdotal evidence from this evening. My wife made two pizzas of the same size. She sliced my daughter’s pizza into 8 pieces and my son’s pizza into 6 pieces. My 5-year-old complained and said that his sister had more, so my wife cut two of his pieces in half so he also had 8 pieces. He was happy! My 5-year-old was the only one to use the word more. On a related note, adults also show conservation errors (e.g.,


  16. aps can be shown a bunch of shapes and a bunch of shapes in a certain order behind a window and raise the blind for a split second and that ape can place them in order.people cant do that because our brains are two crowded with memories and emotions,the calcium bonding and sinaptic order in wich they fire can be disrupdid by a mere change in diet or the ph of our bodies.thats where your cognative response answers will come from.calcium bonding is sinap


  17. brian scott sparks ,brian I only saw that true for a Couple Special Chimps that were studied.Way superior at task than any mature human.I’m not sure your conclusion [calcium bonding & our brains being Too Crowded]is the correct assumption to make.It seems to negate how much Better ‘some chimps’are than humans at this task.Stuff they did was basically Impossiblre for humans to even come close to replicating.Just saying…….


  18. I think these experiments show more about how Adults can misunderstand what’s going on.  The children are right for a sensible understanding of “fair” and “more”.

    For example, with the quarters, one row has 12 inches of quarters, and the other has 17 inches of quarters.  The child is right that 17 inches is more than 12 inches.  It’s the adult who doesn’t understand the child’s concept of “more”.

    Imagine if I showed an adult two identical 12oz cups – one with 8oz of water, and the other with 11oz of gasoline.  Now I ask which one has more liquid.  The adult will say the gasoline cup has more (it’s almost full, and the other is 3/4 full).  The person would be wrong since there is more water – more mass, more molecules.  Or am I wrong for only thinking in terms of mass when the other person was thinking in terms of volume?


  19. Brian Holt Hawthorne, Sorry – posted before reading your post.  I agree.  A much better test would be to have different amounts of a favorite drink and pour the smaller amount into a narrow glass – then ask the child which one they want.


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