Developmental Psychology: Definition, Theories, & Stages
Developmental psychology is the study of how humans develop and change over their lifetimes. What insights can it offer about our progression through life?
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From the outside, it may seem cliché or cookie-cutter to talk about our childhood experiences in therapy: Do all of our present-day challenges really come from what happened when we were young? Do we really need to revisit every upsetting moment from our adolescences?
While effective therapy does not require an exhaustive review of all the things that have happened in your life, these past experiences absolutely matter. |
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What Is Developmental Psychology? (A Definition)
Let’s look at an example of the breadth of approaches developmental psychologists might use. Take the developmental milestone of learning to read, for instance. (Developmental psychologists love to talk about developmental milestones, or important moments and processes that all or nearly all people go through at some point in their lives.) One developmental psychologist might study learning to read from a cognitive perspective, trying to understand what exactly changes in the way a person thinks as they become literate. Another developmental psychologist might study how emotion regulation affects your ability to learn to read, since learning to read is no simple and quick task. Yet another developmental psychologist might conduct research to understand the question: What is the significance for one’s future well-being of learning to read a year earlier, or a year later, than most of one’s peers?
Developmental Psychology Theories
First, there is the stage theory of cognitive development, as proposed by French psychologist Jean Piaget. Piaget (2005) conducted many experiments with children to understand how they develop the ability to think with more complexity and abstraction over time. For example, he sought to establish at what age children develop the ability to understand object permanence. If you show a baby a colorful toy but then hide it behind your back, at what age do they understand that the toy is merely hidden and has not completely disappeared? He found that children begin to understand object permanence—the toy is hidden, not lost—when they are about 24 months old, on average.
Piaget proposed four stages of learning in child development (more on those in a moment). Over time, other researchers have affirmed many of his ideas while also compiling solid evidence that some of his ideas should be revised (Miller, 2022). For example, Piaget proposed a linear progression through those four stages, with children consistently growing in their ability to think abstractly and complexly. However, it turns out that this progression is not as linear as he believed; for example, children may be able to use abstract thinking in one cognitive domain, such as mathematics, long before they can use the same level of abstraction in another domain. And newer methods of testing for these cognitive abilities began to suggest that children develop them earlier than Piaget’s original research indicated. This has led some developmental psychologists to propose that his theory should be applied separately to different domains, while other developmental psychologists argue for choosing a different theory as the foundation of their work instead.
All developmental psychology theories have a few traits in common (Miller, 2022). First, they prioritize a focus on the timing of events and changes in one’s life. For example, although having a parent die is almost always painful and impactful, whether that parent dies when you are a child, a teenager, or an elderly person yourself will strongly shape its influence on you. It is the goal of developmental psychology theories to provide guidance to answer a question such as: “What are the likely differences in impact for me between losing my mother when I am in my teens versus my forties?”
A second common trait is that these theories acknowledge the wide range of developmental trajectories that are possible. Some people are born two months premature, while others are born several days late. The age at which you first go on a romantic date can vary quite widely from one culture, generation, or family to the next. There are personal and environmental influences that separately and together influence the timing of that first date; a good developmental psychology theory can account for these various influences.
Developmental Psychology Stages
Remember Piaget’s stages of development? Here’s a great summary of them if you’d like to know more about his theory:
Video: Introduction to Developmental Psychology: Piaget’s Stages
Developmental Psychology History
Developmental psychology as a field was not really a possibility until scientists began to consider that life could move through highly distinct stages (Cairns, 1998; Walkerdine, 2005). It was not until the 1700s, for example, that scientists began to really think about childhood as a distinct period of time from adulthood. For example, artwork from prior to this time often depicted children as more less adults in miniature (Ariès, 1965). But by the early 1800s, scientists were making the first attempts to describe how organisms develop from birth, and one influential scientist proposed that as we develop, we go from general structures to more organized and complex ones (von Baer, 1828-1837). Although this idea does not apply to all aspects of development, it contains a lot of truth and has inspired a great deal of research done by developmental psychologists, such as Jean Piaget (Cairns, 1998).
By the late 1800s, some doctors and scientists, such as Alfred Binet and G. Stanley Hall, were focusing exclusively on child development, even establishing clinics and research institutes solely for this purpose (Cairns, 1998). This was aided by the effects of industrialization (Walkerdine, 2005). As people worked outside the home more and more in the 1800s, they could no longer watch their children as closely, and the necessity for more schools emerged. As schooling became more commonplace and even compulsory, scientists began to focus on children as having distinct needs from adults (Walkerdine, 2005). More specifically, they began to study how children could best undergo a natural, supposedly linear, progression from being undisciplined and less capable to being civilized and productive adult members of society (Cairns, 1998).
From these origins comes developmental psychology’s focus on normative development: What does each developmental stage look like for the typical person? With time, as we shall see, the flip side of this question—Why do some people experience atypical development, and what does it mean for them?—also became a primary concern of developmental psychologists.
Examples of Developmental Psychology
Another example of a crucial developmental psychology theme is that of the question of nature versus nurture (Cairns, 1998). To what extent do our genes versus our environments determine who we become? As ample research has shown, our genes and environments influence our development both separately and in combination with each other.
Developmental Psychology Topics
Developmental psychologists, although not medical doctors, are also interested in the timing of the acquisition of key motor skills, from throwing a ball to writing one’s first letters (Thelen, 2000). This may be because motor development is often closely related to psychological development.
Another pair of topics from developmental psychology that I think are especially important are the concepts of equifinality and multifinality (Cicchetti & Rogosch, 1996). Equifinality means that a variety of different experiences can all lead to the same result, while multifinality means that a single experience can lead to many different results. These concepts are helpful reminders that we cannot assume that a child’s diagnosis of ADHD, for example, comes from any particular cause, nor that it will inevitably lead to a particular outcome for them in adulthood.
Developmental Psychology Degrees
Developmental psychologists attend both master’s and PhD programs. In the United States, at least, these are focused exclusively on conducting research and learning to teach about psychology.
Developmental Psychology Job Description & Careers
After completing their degrees, most developmental psychologists end up working at colleges or universities and engage in teaching, research, or both (Slater & Bremner, 2017). Some developmental psychologists may also work in settings where care is provided for others; these contexts can range from early childhood care clinics to nursing homes.
Developmental Psychology: Early Childhood
Developmental Psychology: Adolescence
Developmental Psychology Disorders
Finally, like clinical psychologists, developmental psychologists are interested in psychopathology, or the various forms of atypical and impairing psychological disorders that people may develop. However, developmental psychologists approach this topic from their own lens, often called a developmental psychopathology lens (Rutter & Sroufe, 2000), in which they focus specifically on how and why psychopathology develops and how it impacts us throughout the lifespan. This is different from the clinical psychologist approach, which is more concerned with how to treat or cure psychopathology.
Articles Related to Developmental Psychology
Books Related to Developmental Psychology
Final Thoughts on Developmental Psychology
For budding scientists and psychologists interested in taking a broad perspective on the human experience across periods of time and developmental stages, I think developmental psychology is an excellent field to focus on. Developmental psychologists regularly make very meaningful contributions to the fields of education, medicine, and human services, even if they do not work directly in these spaces.
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References
- Ariès, P. (1965). Centuries of childhood: A social history of family life. Random House.
- Arnett, J. J. (1999). Adolescent storm and stress, reconsidered. American Psychologist, 54(5), 317–326.
- Bijou, S. W. (1976). Child development: The basic stage of early childhood. Prentice-Hall.
- Cairns, R. B. (1998). The making of developmental psychology. In R. M. Lerner (Ed.), W. Damon (Series Ed.), Handbook of child psychology: Vol. 1. Theoretical models of human development (5th ed., pp. 419–448). Wiley.
- Cicchetti, D., & Rogosch, F. A. (1996). Equifinality and multifinality in developmental psychopathology. Development and Psychopathology, 8(4), 597–600.
- Cicchetti, D., & Rogosch, F. A. (2002). A developmental psychopathology perspective on adolescence. Journal of Consulting and Clinical Psychology, 70(1), 6–20.
- Hurford, J. R. (1991). The evolution of the critical period for language acquisition. Cognition, 40(3), 159–201.
- Kohlberg, L. (1984). The psychology of moral development: The nature and currency of morality stages (Essays on morality development, volume 2). Harper & Row.
- Miller, P. H. (2022). Developmental theories: Past, present, and future. Developmental Review, 66, 101049.
- Montroy, J. J., Bowles, R. P., Skibbe, L. E., McClelland, M. M., & Morrison, F. J. (2016). The development of self-regulation across early childhood. Developmental Psychology, 52(11), 1744–1762.
- Thelen, E. (2000). Motor development as foundation and future of developmental psychology. International Journal of Behavioral Development, 24(4), 385–397.
- Piaget, J. (2005). The psychology of intelligence. Routledge.
- Rutter, M., & Sroufe, L. A. (2000). Developmental psychopathology: Concepts and challenges. Development and Psychopathology, 12(3), 265–296.
- Slater, A., & Bremner, J. G. (Eds.). (2017). An introduction to developmental psychology. John Wiley & Sons.
- von Baer, K. E. (1828–1837). Über Entwickelungsgeschichte der Thiere: Beobachtung und Reflexion (Vols. 1–2). Bei den gebrüdern Bornträger.
- Vygotsky, L. S., & Cole, M. (1978). Mind in society: Development of higher psychological processes. Harvard University Press.
- Walkerdine, V. (2005). Developmental psychology and the study of childhood. Childhood: Critical Concepts in Sociology, 3, 13–25.
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