Averages can conceal how people and science learn

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Sandy Schaffer
Picture a learning curve. Most of us imagine a smooth upward slope that rises with steady mastery. It is the ultimate image of progress.

But that image, as behavioral sciences writer Bruce Bower reports in “Kids learning curve not so smooth” (SN: 11/26/16, p. 6), may well be an illusion of statistics, created when people look at averages of a group instead of how individuals actually learn. That’s what scientists at the University of Cambridge found when quizzing preschoolers’ developing ability to understand that other people can have false beliefs, an important milestone in the development of a theory of mind.

For many learners, the study suggests, mastery comes in fits and starts, a graphical zigzagging that denotes steps forward and back. Insight into a problem can be quick for some, but many people follow a more meandering path to knowledge and understanding.

I recognize the truth of this in my own life, be it learning about a new subject or (especially) a new skill. I see it in my 5-year-old daughter as she learns to read. If you are not struck by a single dramatic aha! you can still make it work by moving forward, then back, aiming for progress and mastery.

Scientific advances also do not always follow a smooth upward curve. As staff writer Meghan Rosen writes in “Dinosaurs may have used color as camouflage” (SN: 11/26/16, p. 24), paleontologists did have a fairly sudden insight into how to get clues about the colors that decorated dinosaur skin: Look for pigment-containing structures called melanosomes. But identifying these microscopic structures in well-preserved fossils of soft tissue, while distinguishing them from bacteria that might have feasted on the fresh dead dino skin, has been a bit of a zigzag. There’s an ongoing back-and-forth critique between those scientists who claim they’ve discovered melanosomes and those who question such claims. It may be a long time before we know whether we will be able to truly repaint dinosaurs’ colors accurately, or use that information to better understand their lifestyles or habitats (as many scientists working in the field hope). But current investigations are already taking us closer to that goal, even if via a meandering path.

The danger of looking at the average, as evidenced in Bower’s news story, is also at play in Amy McDermott’s story “Lichens are an early warning system for forest health” (SN: 11/26/16, p. 20). Lichens are very sensitive to air pollution, a quality exploited for decades to monitor the air quality of forests and alert forest managers to looming issues. But if you were to look at overall lichen abundance you might not see any problem. Air pollution tends to encourage some species while discouraging others — a subtlety that a lichen average growth rate might miss. With on-the-scene reporting in the Pacific Northwest, McDermott details the history of lichen use in environmental quality studies and the new effort to use lichens as an indicator of climate change in forests.

Looking at averages can tell you part of a story, but it rarely tells you the whole story. What you may miss is the rich variety found in the real world — be it in students or lichens or even scientific perspectives.

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