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Diversity more than doubles learning

U. IOWA (US) — Toddlers who play with a broad array of objects named by shape learn new words twice as fast as those who play with similar objects.

Outside a laboratory setting, one month after training, children in a new study who had been exposed to a diverse group of objects were learning an average of nearly 10 new words per week. Toddlers in a group that were given like objects were picking up four a week—typical for children that age without any special training.

The study is published in the journal Psychological Science.

Researchers aren’t sure how long the accelerated learning continues, but say they can explain why it may have occurred.

All of the children given extra training with words figured out that shape was the most important distinguishing feature when learning to name solid objects. This attention to shape, called a “shape bias,” is not typically seen until later in development.

However, the researchers believe that kids exposed to more variety took the knowledge a step further, also learning when not to attend to shape.

Children in the variable group learned, for example, to focus on material rather than shape when hearing names for non-solid substances.

“Knowing where to direct their attention helps them learn words more quickly overall,” explains Lynn Perry, a doctoral student in psychology at the University of Iowa and lead author of the study.

“The shape bias enhances vocabulary development because most of the words young kids learn early on are names of categories organized by similarity in shape. And, developing the ability to disregard shape for non-solids helps them learn words like pudding, Jell-O, or milk.”

The study included 16 children who knew about 17 object names when the study began. Half of the kids were taught names of objects by playing with groups of toys that were nearly identical; the other half used toys that differed significantly – for example, a small, cloth, jack-o-lantern bucket; a trash bucket with no handle; and a traditional plastic bucket.

When tested on unfamiliar objects that fit into the categories they’d been taught—such as a bucket they’d never seen before—kids in the variable group performed better, demonstrating an ability to generalize the knowledge.

“We believe the variable training gave them a better idea of what a bucket was. They discovered that the buckets were all alike in general shape, but that having a handle or being a particular texture didn’t matter,” Perry says.

“In contrast, the children exposed to a tightly organized group of objects developed such strict criteria for what constitutes a bucket that they were reluctant to call it a bucket if it was different from what they’d learned.”

In additional tests, researchers looked at whether the tots learned names of new objects by focusing on substance or shape. The variable group tuned into shape for solids but material for non-solids, a distinction children aren’t typically capable of making until the age of 3, when their vocabulary reaches 150 nouns.

Further investigation is necessary to pinpoint exactly why the variable group had more success in this area, but the researchers say their study is the first to show that variability at the local level can help children learn something more global about the importance of particular object features for different categories of things.

“What children learn about one category sets the stage for their future learning,” says Larissa Samuelson, assistant professor of psychology.

“Similar exemplars help children learn specific names for specific objects. But variable exemplars teach them more about the whole category, which helps them learn names of other new things faster.

“That’s why kids in the variable group learned more outside the lab—they learned more about naming in general, not just specific examples of the specific categories they’d seen in the lab.”

The study was funded by the National Institute of Child Health and Human Development.

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