How our Minds Develop through Piagetian Stages

Your activity score reflects the percent correct on a set of puzzles, designed to reveal how you think about hypothetical situations. Maybe it surprised you. Maybe it felt familiar. It’s a snapshot of how your mind currently works, and maybe a nudge to think on a qualitatively deeper new way?

Jean Piaget created the first overarching theory of children's development. To describe each stage Piaget and others designed tasks distinguishing one stage from another. Our activity involved completing puzzles you might respond one way or another depending on your stage of development. Your score is a percent correct, an it corresponds with a stage (table 1). Let's explore the stages!

🐣 Sensorimotor Thought (birth to ~2 years)
Infants learn through movement - grasping, tasting, crawling. They don’t yet think in symbols, but they build knowledge through their senses and bodies. A key set of milestone here is object permanence: - coming to understand how things still exist even when unseen. Just by engaging with this activity, you demonstrate having moved past this stage. You’re using representational thought, like language, symbols, and imagination.

🌱 Pre-operational Thought (~ 2 to 7 years old)
Toddlerhood and early childhood is a stage filled with vivid imagination, but not yet logical. Children may struggle with consistency and perspective. They believe the moon follows them, or that their toys have feelings. It’s rich, but not yet structured. Scores between 0% and 25% reflect this early, emotionally expressive style of reasoning.

🧱 Concrete Operational Thought (~ 7 to 12 years old)
Logic starts to bloom in later childhood, but this stage is rooted in the tangible. Concrete thinkers solve real-world problems well but may find hypotheticals confusing or irrelevant. Scores between about 25% and 55% reflects strong reasoning within concrete, familiar contexts.

🌉 Formal Operational Thought (~ 13 years old and older)
From adolescence and beyond, formal reasoning shows up in tasks like imagining a world where gravity is reversed and predicting what changes would follow. Maybe you craft an argument for a belief you don’t hold, just to test its logic. These activities ask us to think not just about what is, but what could be.

Now the mind can fly. Formal thinking tests ideas, imagine possibilities, and follow chains of logic.. It asks us what else could be true? Scores between 55% and 100% reflect this expanding capacity. Higher scores suggest formal reasoning across a wider range of situations.

Some of us live more in the concrete. Others love abstract thought. Piaget saw these not as preferences, but as qualitatively different ways of thinking. And while not everyone reaches formal thought at the same age - or even in the same way - many of us keep growing, stretching, and shifting culminating in formal operational thought.

This activity is grounded in the work of Jean Piaget, who studied how children make sense of the world (e.g., Piaget, 1952; Dixon, 2003). He believed we develop through stages, each unlocking new tools for understanding. Research supports parts of this, with evidence of both a stage-like shift from pre-operation of concrete thought (e.g., Tomlinson-Keasey et al. 1979) and a stage-like shift from concrete operations to formal operations (e.g., Martorano, 1977). Once we cross a threshold to become capable of a stage, we experience horizontal décalage - rather than failing every task of a stage one day and passing them all the next, we see passing tasks happen rapidly after one another, often in a predictable sequence.

Though Piaget studied children and adolescents, later thinkers extended his model into adulthood. Robert Kegan (1982), for instance, explored how adults may continue to deepen their ways of making meaning through increasingly complex, layered perspectives.

Piaget didn’t just chart milestones. He asked how we move through them. He identified three core processes (e.g., Siegler, 2016):

Assimilation: We fit new ideas into what we already know, like adding a book to a shelf.

Accommodation: We adjust our mental shelves, or build new ones, to make room for ideas that didn’t fit.

Equilibration: We try to balance the old and new. When things don’t quite match, we feel disequilibrium, which nudges us to reorganize our shelves. And when our disequilibrium gets so much reorganizing our shelves can't help, we build ourselves a new study. We shift stages.

Understanding your stage of thought can help you make sense of challenges in school, relationships, and everyday life. It can reveal why abstract courses feel harder or more exciting, why some debates feel energizing while others feel confusing, and how your mind is preparing to meet new complexities.

Developing formal thought isn’t automatic. It takes facing challenges and choosing reflection and practice.

Here are some ways to help yourself move through Piaget's developmental stages:

Play with "what if" questions. Imagine alternate outcomes.

Think about your thinking. Notice your process. Notice your thoughts, feeling, and perceptions. And reflect on them.

Explore other perspectives. Try viewpoints differing from your own.

Engage with abstract ideas. What is the meaning and purpose of life? What do we owe one another? What kind of society should we move towards and how could we get there. Just some questions to ponder.

Design and test. Try building or experimenting with your ideas.

You’re not leaving concrete thought behind. You’re expanding your reach. Learning to move between the visible and the possible.

Piaget’s theory profoundly shaped the field of Developmental Psychology, But in the last several decades it's fallen out of favor as we improved our scientific rigor and we discovered gaps and contradictions with his theory. Among the biggest challenges:

Nativism says he underestimates early infant abilities. Baillargeon (1987) suggests infants show object permanance earlier than Piaget proposed.

Cultural context matters more than Piaget recognizes. Vygotsky (1978) suggests all learning is social and shaped by culture.

Development isn’t always stage-like. Growth may be more continuous and variable (Demetriou et al., 2010).

Still, Piaget found insights into how we build understanding, and how we wobble and rebalance. And several scholars of children's development suggest criticisms of Piaget, while having some validity, often throw the baby our with the bathwater (e.g., Grobman, 2006; Lourenço & Machado, 1996). Pun intended.

Whatever your score, you’re part of something beautifully human: the lifelong process of making meaning. Development isn’t a race. It’s a journey of unfolding. Whether you’re grounded in the real or reaching for the possible. You’re thinking. You’re growing. And there’s wonder in every stage.

Uneasy Feelings about Your Results?
Please remember your results with any activity are not who you are. Your results are a 'snapshot' of a moment when you did an activity. It's just one measure, a single thread, of the many strands of who you are. Any result is a guess with statistical error. And it's possible the measure is flawed in a way so it doesn't work for you. Please do not think of your results as definitive dogma. Instead they're a starting point for our self reflection. Please keep in mind too, self-reflection can feel uncomfortable. "Bad" feelings are not actually bad. They're information. So, even if your activity result is inaccurate and flawed, you might ask yourself what your feeling is trying to tell you? Trusted teachers, friends, and therapists can be helpful. I wrote an essay elaborating with concrete examples how we can appreciate uneasy feelings about our activity results.

Scholarly Information?
You're welcome to use Copernican Revolution activities and essays for your thesis and studies. Having information about scholarly aspects like psychometric data, activity design details, and norm calculations may help. The primary focus of my essays is connecting educated laypersons with psychology. To help people like you, with advanced academic interests, I add an appendix with each activity.

Baillargeon, R. (1987). Object permanence in 3½- and 4½-month-old infants. *Developmental Psychology*, 23(5), 655–664.

Demetriou, A., Mouyi, A., & Spanoudis, G. (2010). The development of mental processing. In W. F. Overton (Ed.), *Biology, cognition and methods across the life-span* (Vol. 1, pp. 306–343). Wiley.

Dixon, W. E. (2003). *Twenty studies that revolutionized child psychology*. Prentice Hall.

Grobman, K. H. (2006). Jean Piaget - Did he do a science o Developmental Psychology? CopernicanRevolution.org

Kegan, R. (1982). *The evolving self: Problem and process in human development*. Harvard University Press.

Lourenço, O., & Machado, A. (1996). In defense of Piaget's theory: A reply to 10 common criticisms. *Psychological Review*, 103(1), 143–164.

Martorano, N. (1977). The consistency of formal reasoning in the adolescent. *Genetic Psychology Monographs*, 95, 147–224.

Piaget, J. (1952). *The origins of intelligence in children* (M. Cook, Trans.). International Universities Press. (Original work published 1936)

Siegler, R. S. (2016). *Children’s thinking* (5th ed.). Pearson.

Tomlinson-Keasey, C., Eisert, D., & Keasey, B. (1979). Concrete operational thought: A transitional phase. *Child Development*, 50(3), 700–708.

Vygotsky, L. S. (1978). *Mind in society: The development of higher psychological processes*. Harvard University Press.