Categories above the Basic Level𓇯 tend to be collections of similar-in-some-relevant-sense basic level objects. They're harder for children to learn, possibly because they don't usually provide a mental image.
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If I ask you to picture a bird in your head, it’s likely to be an ordinary bird you can find in your yard. Most picture the typical "small brown songbird." Few picture penguins. Similarly, if I ask you to picture a dog or a cat, you can probably easily do it. But asking you to picture a “mammal” seems weird. What you'll do is picture some basic level animal – a dog, perhaps – and then picture *that*.
Another problem with more abstract categories is that we tend to think of them only when confronted with collections of basic-level objects. More than once, Dawn has asked for help moving a couch. She never points at a couch and asks if I can help move that “furniture.” That would be weird. She says “couch.”
However, if she decides to paint a room, she’ll ask me to help move the furniture out of it: the collection of chairs, couches, end tables, and lobster trap that live in our front room, for example.