“You May Also Like: Taste in an Age of Endless Choice” A book by Tom Vanderbilt To see long excerpts from “You May Also Like” at Google Books, click here.

You know that when you search for the best price on shoes or a dishwasher or a hotel online, Google is watching you. But so are armies of marketers, psychologists and neurologists. They don’t just want to know what you ultimately decide. They want to know why. Why a blue dress rather than green? Why Coke rather than Pepsi? Did you actually read the online reviews? Did they sway you?

It turns out that our reasons, from shopping decisions to the songs on our playlists and the dog breeds we find adorable, are shockingly arbitrary. In “You May Also Like,” Tom Vanderbilt parses out what we know about the science of personal preferences. In this lively, wide-ranging study, Vanderbilt argues that “our tastes are so elusive, even to us”; no matter how strongly we announce our opinions, he marvels at “what a fleeting grasp we have of the things we put in our mouths or before our eyes.”

Vanderbilt begins by analyzing the world of search engines, on sites such as Amazon, Netflix and TripAdvisor, to see how accurately their algorithms can predict our tastes. He is particularly interested in how we’re influenced by online reviews — and by how many of them are fake: He discovers that up to 70 percent of reviewers haven’t read the book or stayed in the hotel. Researchers at Cornell claim to be able to spy fake hotel reviews with 90 percent accuracy.

Vanderbilt also looks at the correlation between taste and socioeconomic status, and spends time with experts — a famous cat-show judge, panels of wine and cheese tasters — to see how their processes of discrimination differ from those of ordinary consumers. Like Eskimos who know a hundred words for snow, the taste czars in the lab at McCormick, the spices and flavoring company, can identify and describe all 23 flavors in a Dr Pepper. It gets weirder than that: “Trained sensory panelists can even tell which women have consumed garlic pills based on the scent of their amniotic fluid alone.”

“You May Also Like” is full of such bizarre tidbits. It’s a dense distillation of current research — and as such, not exactly a breezy read. Vanderbilt includes more than 60 pages of footnotes, from scholarly sources as diverse as the International Journal of Psychophysiology and the Journal of Interactive Marketing, about studies as different as “The Revolution Will Probably Wear Mom Jeans” and “Neural Portraits of Perception: Reconstructing Face Images From Evoked Brain Activity.” The footnotes have a David Foster Wallace-like wit as Vanderbilt calls our attention to such issues as whether people find doughnuts less yummy if they taste them in a salmon cannery and whether rats enjoy grape Kool-Aid more if it is infused directly into their stomachs.

Vanderbilt makes a convincing argument about the tyranny of popularity in determining our choices. We like things better when we become more familiar with them — whether it’s a vegetable, a painting or a tune. Things that are popular tend to get more so. You’d think that having access to millions of songs on Spotify would give less-renowned bands a chance, but you’d be wrong. “The route to the top of the charts has in theory gotten more democratic, less top-down, more unpredictable. … But the hierarchy of popularity at the top, once established, is steeper than ever. In 2013, it was estimated that the top 1 percent of music acts took home 77 percent of all music income.”

The importance of popularity might seem like an easy equation, but on the other hand, we also crave novelty, and “exposure contains a hidden peril: We begin to like some things less the more we are exposed to them.” Vanderbilt is quite funny about hipsters and their desperate wish to belong to the cool group — but also to be individual, and thus recoiling from others who sport chin beards and drink craft beer. “The subtle movement of people trying to be like each other and people trying to be different from each other” is not, by the way, an exclusively human trait. He references one zoological study in which a Zambian chimp put a blade of grass in her ear, for no reason whatsoever, and the other chimps, finding the look fetching, copied her.

“You May Also Like” is intended for a lay audience, and Vanderbilt mostly succeeds in making his summaries of the science clear and engaging. Sometimes the array of subjects can get dizzying; Vanderbilt is fond of a quick jump-cut between past and present, and he can overcompress, as he does in one section where he jams together Oscar Wilde, Saks Fifth Avenue, the 19th-century novelist Charlotte Perkins Gilman and Steve Jobs. The effect can be like too many pop-up windows open and flashing at once. Still, he is to be commended for the sheer range of material he makes accessible.

Vanderbilt is especially persuasive in his explanation of how “liking is really about anticipation and memory. Even as you are looking forward to something, you are looking backward to the memory of the last time you enjoyed it.” “You May Also Like” explains why people are so fond of music they listened to in college and why they’re so bad at realizing that their tastes are going to change — see bell bottoms, bad tattoos and what Vanderbilt calls “the High School Popularity Problem,” which is how hard it is to look past the “radiant prom king” to the “terminally shy geek, prone to be picked on or aggressively ignored, a seemingly unaccomplished sort who goes on to change the world.”

Lisa Zeidner’s most recent novel is “Love Bomb.” She teaches in the MFA program in creative writing at Rutgers University at Camden.

©2016, Washington Post Book World Service/Washington Post Writers Group

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