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Macmillan Childrens Publishing Group


How Our Bodies Shape Our Minds

Dennis Proffitt and Drake Baer

St. Martin's Press




FOR REASONS THAT NO ONE REALLY UNDERSTANDS, we have little or no memories about what it was like to be an infant or toddler. And, of course, we can’t simply ask infants to report on their experience because they can’t yet talk. Tapping into the developing minds of infants and toddlers requires terribly clever researchers asking the right sort of questions. What kind of bodies do infants and toddlers have? How do their bodies change over time? And with these bodies, what do they do? The most general finding deriving from this research is that the simple exercise of their developing motor skills teaches children about what the world is and how it works. This is how human knowledge gets off the ground. As children develop, they first discover that the world is filled with gum-able things that, as time goes by, maybe turn out to also be graspable, throw-able, roll-able, or pliable things. No one initially teaches children how to explore their environment. The cradle of knowledge is exercise and play. Children learn to interpret their experience by actively creating it via crawling, walking, falling, and so forth. Moreover, what we learn in childhood forms the foundation for all the new experiences and discoveries that are to come. And, correspondingly, if we’re going to run studies that get at what it’s like to be a child, we need to design experiments that allow children to roam free.


ON ANY GIVEN DAY, New York University’s Infant Action Lab is abuzz in pint-size activity. Led by the pioneering developmental psychologist Karen Adolph, the lab has revealed much about how kids come to discover what their bodies can do in the world in which they find themselves. On the day of Drake’s visit, the range of work being done spoke to the scope of the team’s inquiries. Research assistants were busy coding data that had been sent back from far-flung laboratories around the world: one was studying a traditional cradling practice in central Asia, where babies are swaddled to the point of immobilization in a cradle for 20 some hours a day, up until 18 months of age. (Don’t worry; they turn out fine.) Other Action Lab researchers were going into homes and observing the natural activity of tots. Parents were bringing five-year-olds into the lab to see how they handle what Adolph calls the “hidden affordances of everyday objects,” as in, how kids learn the opportunities for active play afforded by the objects in their enlarging surroundings, whether it’s navigating a Kleenex box or opening a water bottle.

Adolph is tall, slim, and moves about her lab with a certain frenetic precision—the product, one surmises, of decades spent shepherding toddlers, their mothers, and a constant stream of graduate students, postdocs, and undergraduate research assistants. To mix archetypes, she’s equal parts fairy godmother and mad scientist, an iconoclast turned matriarch who, by virtue of her area of study, has been forced to invent not only novel hypotheses but the many bizarre, fascinating platforms, tumbling mats, and quasi–jungle gyms needed to test out what small humans are actually doing as they learn to perceive the world and move through it. Her enthusiasm is infectious. What could be more interesting than studying how, through development and play, our species achieves its commonsense understanding of the world?

Enter through the doorway into the lab, round the corner past the computer bay, and you’re in a bright, welcoming playroom, what feels like the stage for a high-production-value children’s TV show. This is where the action in the Infant Action Lab takes place. The atmosphere is opposite the sterility that the word laboratory might conjure up: Adolph’s lab is brightly but not oppressively lit. Primary colors abound. Across the broad center of the room lies a recessed strip in the shape and manner of a long-jumper’s pit but solid instead of sand. On the near wall stands shelf after shelf of toys. On the far wall hangs what looks like a horizontal ladder, which turns out to be an adjustable set of monkey bars; and standing next to the other walls are apparatuses for which Adolph is perhaps best known in academic circles. Adolph wants to know, not just what infants can do but also what they think they can do. For example, a typical study might investigate the maximum steepness of an incline that a crawling infant can descend without tumbling, the maximum steepness that they will attempt to crawl down, and how their awareness of their own abilities changes with experience. To answer such questions, Adolph employs platforms and ramps, the height and angle of which can be adjusted with great precision. The fruit of a longtime industrial design collaboration, these apparatuses allow for hills and cliffs and gaps to form and disappear, depending on the experiment in question. Every apparatus has shock-absorbing feet, so that if the floor vibrates this way or that—a real danger when the subway rumbles beneath the building—equilibrium can be maintained. On top of that, the entire room is under the surveillance of cameras, so all behavior therein can be captured and later coded. One is reminded of the Transformers movies as Adolph demos her wares—all gears and garage door openers, slopes and bars, feats of sophisticated, yet utterly approachable, engineering. For all the complexity, the lab is a cozy, easy place for babies and parents to be. “Even when baby is in a headset, everybody is happy,” she says.

Infant researchers are some of the most creative scientists around—they have to be. Infants don’t talk, so you can’t ask them questions. Unlike the young adults, who make up most of the participant pools for psychology experiments, babies don’t comply with instructions. You have to set up experimental circumstances in which young ones can behave freely and thereby show the experimenter what they know and are capable of doing. When study participants come into Adolph’s lab, the process begins with Adolph or a colleague affirming consent with the caregiver. Then it’s time to deck the child in whatever technological rigging is necessary: like a tiny head-mounted camera for eye-tracking studies or a weighted vest or Teflon shoes to test how kids compensate for changes to their body’s dynamic balance. The actual running of experimental trials is “a coordinated circus,” Adolph warns, with the parent standing to the side and a researcher keeping close to the baby in case they fall. If it’s off a platform—which happens with scientific regularity in novice walkers—then the researcher has to pluck them out of the air.

In the vernacular of psychology, Adolph strives for “ecological validity”: if you set up an experiment to be more like real life, you’ll likely get more accurate information about human behavior as it naturally occurs. Consider the matter of a baby’s first steps. For more than a century, researchers had assumed that toddlers walked in straight paths, taking the shortest, most efficient route from point A to point B, right? Adolph thought the same, until she stumbled on to a series of results indicating otherwise. For one fateful experiment, the graduate student she was working with wasn’t quite handy with the catch-the-infant-out-of-the-air-drill, so they moved the trials from a raised platform to the floor. Then, when asking the tot to walk, the kid did everything but go in a straight line. Adolph sensed she was on to something, so she contacted every living researcher whom she knew had done similar walking studies, and they all reported the same pattern. Everybody threw out more data than they kept, because the babies were so reliably irregular. Wandering about was the norm; a straight line was the exception.

The assumption that infants walk in a straight line speaks to a larger problem in science, Adolph says: experiments are run in a manner that’s convenient for the experimenter, like testing locomotion in a straight line. Then theories are constructed for explaining the phenomenon, and these theories become taken as truth. It’s a classic example of what William James, one of the fathers of the field, termed the psychologist’s fallacy: rather than seeing human behavior as it is, psychologists’ views of human nature are biased by their own preconceptions about what it should be.

Karen Adolph is the rare researcher who can set her assumptions aside when the results of an experiment turn out other than expected. When she found that the babies in her studies didn’t walk in straight lines, as the research literature suggested they should, she decided to study how infants naturally walked when unconstrained. The results of these studies showed that babies dance their way through their world following their own creative muse as opposed to the dictates of efficiency. One could make infants “walk the plank” and thereby study linear walking, but what would the results mean? This is not how infants naturally walk. If you want to study what infants do, then you need give them the freedom to do what they want. Adolph is the master of this ecological approach to infant development.

One of Adolph’s formative moments came when she was first immersing herself in psychology as a college undergraduate. She recalls coming to her adviser distraught, weepy about a lecture on perception, presented in its classical, conventional way. Mainstream accounts of perception, both then and now, resemble the cliché about history being one damn thing after another. For visual perception, that means: first light forms an image on the retina, and then certain features of the image are extracted, sent to the visual cortex for processing, which is followed by still more processing, and so it goes. Listening to or reading such accounts would never suggest that all of this is going on within a living, behaving, goal-directed person.

“This just can’t be like this, this can’t be how we see,” she remembers her undergraduate self saying through tears. Her adviser looked at her and said, “Well, it’s not.” Then he reached to his bookshelf and said, “Here, read this.” He handed her The Senses Considered as Perceptual Systems, the second book by James J. Gibson. “To me, it was like discovering religion,” Adolph says. “That was my biggest epiphany.” It lead her to James and his developmental psychologist wife, Eleanor Gibson, known together affectionately as Jimmy and Jackie.1 (For the sake of clarity, we’ll refer to the pair as Jimmy and Jackie.) In partnership, the Gibsons were revolutionizing how we think about visual perception and its development.


COMMON SENSE TELLS US that the world is as it appears, that our experience of the world is the world. We see what is there. Every time we stop at a curb rather than stepping out in front of an oncoming bus, we affirm our belief that it is best to believe in the veracity of our experience. This naive realism asserts that there is a one-to-one correspondence between the world and our experience of it.

Once examined, however, naive realism fails to jibe with the facts. To begin with, the stimulus information for vision (light’s input) is generally assumed to be an image projected on the back of the eye—the retina—where the neural photoreceptors are located. This retinal image is two-dimensional, upside-down, and lacking in the constant properties that are prevalent in perception. For example, the size of an object’s projected retinal image varies with distance—the image gets bigger as the object gets closer—and yet our perceptions are of objects having constant sizes. Hold a pencil out at arm’s length, then bring it toward your face. Notice that the pencil’s appearance gets bigger while its actual size is perceived to remain the same.

Copyright © 2020 by Dennis Proffitt and Drake Baer.