Growth curves vs. individual growth

Individual growth trajectories often don’t stick to statistically determined expectations.

The illustration above depicts the growth trajectory of a woman named Eleanore. Between the ages 12 and 68, she completed two different developmental assessments several times. The first assessment was the LRJA, a test of reflective judgment (critical thinking), which she completed on 8 different occasions. The second assessment was the LDMA, a test of decision-making skills, which she completed four times between the ages of 42 and 68. As you can see, Eleanore has continued to develop throughout adulthood, with periods of more and less rapid growth.

The graph on which Eleanore’s scores are plotted shows several potential developmental curves (A–H), representing typical developmental trajectories for individuals performing in different levels at age 10. You can tell right away that Eleanore is not behaving as expected. Over time, her scores have landed on two different curves (D & E), and she shows considerable growth in age ranges for which no growth is expected — on either curve.

Eleanore, who was born in 1942, was a bright child who did well in school. By the time she graduated from high school in 1960, she was in the top 15% of her class. After attending two years of community college, she joined the workforce as a legal secretary. At 23 she married a lawyer, and at 25 she gave birth to the first of two children. During the next 15 years, while raising her her children, her scores hovered closer to curve E than curve D. When her youngest entered high school, Eleanore decided it was time to complete her bachelor of science degree, which she did, part time, over several years. During this period she grew more quickly than in the previous 10 years, and her LRJA scores began to cluster around curve D.

Sadly, shortly after completing her degree (at age 43), Eleanore learned that her mother had been diagnosed with dementia (now known as Alzheimer’s). For the next 6 years, she cared for her ailing mother, who died only a few days before Eleanore’s 50th birthday. While she cared for her mother, Eleanore learned a great deal about Alzheimer’s — from both personal experience and the extensive research she did to help ensure the best possible care for her mother. This may have contributed to the growth that occurred during this period. Following her mother’s death, Eleanore decided to build upon her knowledge of Alzheimer’s, spending the next 6 years earning a Ph.D. focused on its origins. At the time of her last assessment, she was a respected Alzheimer’s researcher.

And now I must confess. Eleanore is not a real person. She’s a compilation based on 70 years of research in which the growth of thousands of individuals has been measured over periods spanning 8 months to 25 years. Eleanore’s story has been designed to illustrate several phenomena my colleagues and I have observed in these data:

First, although statistics allow us to describe typical developmental trajectories, individual development is usually more or less atypical. Eleanore does not stay on the curve she started out on. In fact she actually drops below this curve for a time, then develops beyond it in later adulthood. She also grew during age-ranges in which no growth at all was expected. Both life events and formal education clearly influenced her developmental trajectory.

Second, many people develop throughout adulthood — especially if they are involved in rich learning experiences (like formal schooling), or when they are coping productively with life crises (like reflectively supporting an ailing parent).

Third, developmental spurts happen. The figure above shows a (real) growth spurt that occurred between the ages of 46 and 51. This highly motivated individual engaged in a sustained and varied learning adventure during this period — just because he wanted to build his interpersonal and leadership skills.

Fourth, developmental growth can happen late in life, given the right opportunities and circumstances. The (real) woman whose scores are shown here responded to a personal life crisis by embracing it as an opportunity to learn more about herself as person and as a leader.

My colleagues and I find the statistically determined growth curves shown on the figures in this article enormously useful in our research, but it’s important to keep in mind that they’re just averages. Many people can jump from one curve to another given the right learning skills and opportunities. On the other hand, these curves are associated with some constraints. For example, we’ve never seen anyone jump more than one of these curves, no matter how excellent their learning skills or opportunities have been. Unsurprisingly, nurture cannot entirely overcome nature.

Growth is predicted by a number of factors. Nature is a big one. How we personally approach learning is also pretty big — with approaches that feature virtuous cycles of learning taking the lead. And, of course, our growth is influenced by how optimally the environments we live, learn, and work in support learning.


Find out how we put this knowledge to work in leader development and recruitment contexts, with LAP-1 and LAP-2.

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