"Curiosity Depends on What You Already Know," Zach St. George for Nautilus:

Scientists who study the mechanics of curiosity are finding that it is, at its core, a kind of probability algorithm—our brain’s continuous calculation of which path or action is likely to gain us the most knowledge in the least amount of time. Like the links on a Wikipedia page, curiosity builds upon itself, every question leading to the next. And as with a journey down the Wikipedia wormhole, where you start dictates where you might end up. That’s the funny thing about curiosity: It’s less about what you don’t know than about what you already do.

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Brain studies suggest that this “novelty bonus”—the additional weight we give to new options—stems at least in part from the euphoric feeling it gives us. For instance,  a 2007 study found that, like Pavlov’s dog salivating at the ring of a bell, the part of our brain that processes rewards like love and sweets activates when we expect to find something new, even if that expectation doesn’t play out. These findings, the researchers conclude, “raise the possibility that novelty itself is processed akin to a reward.”