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An inquisitive physicist delves into the psychology and neuroscience of human curiosity

Why: What Makes Us Curious

Mario Livio
Simon & Schuster
268 pp.
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Was it really curiosity that killed the cat? In Why: What Makes Us Curious, astrophysicist Mario Livio provides the answer, although I won’t reveal it here (are you curious yet?). In the book, Livio explores curiosity by using inquisitive people, including scientists, artists, and philosophers, as anecdotal examples. He also presents ideas from psychological and neuroscientific experiments to explain what happens in the various parts of the brain when curiosity is stimulated.

Livio—who was drawn to the subject by his own lifelong curiosity— begins by describing different kinds of curiosity, as defined by the 20th-century psychologist Daniel Berlyne. “Perceptual curiosity,” Berlyne argued, is aroused by new, ambiguous, or puzzling climates. Picture the reaction of an urban child seeing a yak for the first time.

“Epistemic curiosity,” Livio writes, quoting Immanuel Kant, is the “appetite for knowledge.” This, he argues, has been a main driver of scientific inquiry throughout history.

“Specific curiosity” is exactly what you’d expect: wanting a specific piece of information. “Diversive curiosity,” on the other hand, refers to both “the restless desire to explore” and “the seeking of novel stimulation to avoid boredom.” As an older adult, I was relieved to read that although perceptual and diversive curiosity may decline with age, “[s]pecific and epistemic curiosity … apparently stay fairly constant throughout much of adult life.”


Curiosity is often portrayed as negative (or fatal in the case of cats), but novelty can help maintain attentiveness.

Livio has a way of indulging his readers, inviting them to draw parallels between their own inquisitive tendencies and those of history’s geniuses. Who wouldn’t want to compare themselves to Leonardo da Vinci and Richard Feynman, whom Livio believes possessed the most curious minds that ever existed? Likewise, readers may discover similarities between their own sense of curiosity and those of living polymaths like philosopher and linguist Noam Chomsky, astronaut Story Musgrave, Queen rock guitarist Brian May (who also possesses a Ph.D. in astrophysics), or the columnist Marilyn vos Savant (of “Ask Marilyn” fame), whose IQ has been measured at a “staggering 228.”

Some of the early ideas about scientific curiosity were inspired by the 19th-century philosopher and psychologist William James, who proposed that “metaphysical wonder” is a response to inconsistencies in our understanding of the world, “just as the musical brain responds to a discord.” Much of the contemporary research on curiosity, however, is rooted in psychologist George Loewenstein’s 1994 “information-gap theory.”

The gap, according to Loewenstein, occurs when we encounter scenarios that are incompatible with our existing understanding of how the world works. Curiosity, he argued, comes into play when we try to reconcile reality with expectation. How, though, do we determine just how much we know and don’t know?

Over the years, psychologists have spotted other problems with the information-gap theory. For one, the theory regards curiosity as a negative or unpleasant state, but many experiments have found that novelty and variety are often considered “positive and enjoyable experiences that fuel excitement and attentiveness.”

For me, the neuroscientific evidence was more persuasive than the psychological research. In 2009, for example, Caltech researchers tried to identify the neural pathways of epistemic and specific curiosity. While the participants answered trivia questions, scientists scanned their brains using functional magnetic resonance imaging (fMRI). The brain regions activated included the left caudate and the lateral prefrontal cortex, areas that are “energized” (as Livio describes it) if a reward is anticipated, which suggests “that the acquisition of knowledge and information has value in our minds.”

In another study, researchers at Leiden University in the Netherlands scanned the brains of participants while they tried to identify intentionally blurred objects. Perceptual curiosity, they found, activates brain regions known to be sensitive to unpleasant conditions. When the object was revealed, however, the participants’ reward circuitry was activated. Livio concludes that “being perceptually curious is a bit like being deprived, conflicted, or hungry,” whereas satisfying one’s curiosity is “comparable to having good food, good wine, or good sex.”

Livio’s writing style lacks the poetic feel of the recently published translations of books by the theoretical physicist Carlo Rovelli. But his writing is straightforward and (mostly) conversational. He seems comfortable in story-telling mode, especially when he relates one of the book’s many anecdotes.

Ultimately, this cogent book presents the scientific research on curiosity in understandable ways without too much jargon. It answers many (although not all) of our potential questions about curiosity—including what many originally believed killed the cat.

About the author

The reviewer is a freelance writer and critic based in South Dakota.