Researchers from the University of Iowa (UI) studied how 16 month olds learn the words for non-solid objects—things as oatmeal or applesauce or milk—that infants generally take longer to learn and found that those who messed with the substance the most learned the words more quickly. Babies' brains usually pick up words for more immutable objects such as blocks, apples, or daddy, more easily because they can prod and pinch them and they remain the same, more or less, while non-solid objects are a bit more confusing. Think about applesauce: sometimes it's shaped like a bowl, sometimes like a spoon and sometimes like a big blob on the floor. Or consider the similarities between glue and milk; if you didn't touch them, they could seem pretty similar.
To test how toddlers learned the names of gloppy, changeable substances, researchers introduced 14 oozy items, mostly things the kids could safely put in their mouths, like applesauce, pudding, juice, or soup. As they offered the kids the items, they gave them made up names, such as "dax" or "kiv." A short while later they asked the kids if they knew the name of one of the substances, presented in a different size or shape. Kids who could remember the name of the item were obviously relying on more than just what it looked like.
The kids who had really got their hands—and sometimes the walls or floors—dirty, seemed to be the ones who understood the differences in texture or viscosity better. All that fooling around was actually learning. It also helped if they were in a high chair. "It turns out that being in a high chair makes it more likely you'll get messy, because kids know they can get messy there," said Larissa Samuelson, associate professor in psychology at UI, who with doctoral student Lynn Perry and others, oversaw the Developmental Science paper. "Playing with these foods there actually helped these children in the lab, and they learned the names better."
Image: Messy child, via Shutterstock