But those skills don’t magically appear; they develop over time. And it hasn’t been clear exactly how a 1-year-old who doesn’t have those capabilities puts objects and names together. All that was clear was that the baby could—somehow. And while some insight has been gleaned by studying babies, sticking a kid in a sterile lab doesn’t exactly replicate the chaos and clutter of daily life.

So Smith and her colleagues essentially got on babies’ level to figure it out. They put head cameras on 8- to 10-month-olds to look at egocentric vision—basically, what each baby saw during the day. Many people assume, Smith told me during a phone conversation, that what babies and adults see is pretty much the same. After all, they’re living in the same houses, riding in the same cars, and going on the same grocery runs. But that turns out not to be the case, Smith said. Babies aren’t as good at controlling their bodies, and, when they can, they aren’t interested in looking at the same stuff as adults. As a baby develops, his visual world changes, Smith added, meaning a 3-month-old has an entirely different set of visual experiences than does a 1-year-old, who will have different experiences than a 2-year-old.

The researchers wanted to get a sense of the visual worlds of babies who are just shy of the age at which children utter their first words. They decided to focus on mealtimes, because babies eat multiple times each day, often in different contexts—say, in a high chair at breakfast and then in a stroller a couple of hours later on the way to the park. Ultimately, in a theory that Smith and her colleagues have dubbed the “pervasiveness hypothesis,” they found that objects that babies see most consistently are often the first words they say. In other words, babies see stuff all day long—toys and pets, tables and chairs, clothes and food. But what they look at often varies. There are a limited number of things—a bottle, for example—that babies see each time they eat. And “bottle” is more likely than the more seasonal “strawberry” to be among the first words a baby learns.

The researchers suggest that visual experience is the key element in learning first words. To make a word “stick,” it may matter more that a baby sees a bottle often than whether his parents are pointing at it and saying “bottle.” And the more often a baby sees that bottle, the more able he is to identify it in more visually cluttered situations. (If he sees it every day on an otherwise empty high chair, he’ll be more likely to recognize a bottle on a shelf next to diapers and teething rings at Target.) That could have implications for how kids with delayed speech and other disorders are treated: potentially through visuals rather than something else. If a kid has trouble learning words, he might have a visual-processing issue, or he might live in a house where he doesn’t see objects consistently.