Is Twitter “making” us stupid? Are phones “making” us lonely? Do today’s kids have a lower tolerance for boredom, because screens? These kinds of freshman-essay, conventional-wisdom hypotheses about tech’s effects on our collective mental state can sometimes feel impossible to discuss in a productive way. The conversation is too broad; there are too many variables; it’s too alarmist and turns me into a knee-jerk contrarian. (Come on! Surely kids have always been distractible.) Undaunted by the challenge of talking about these matters intelligently, historians Luke Fernandez and Susan Matt have a new book, Bored, Lonely, Angry, Stupid: Changing Feelings About Technology, From the Telegraph to Twitter, that walks through a lot of complicated history and leaves you more confused than ever. In a good way.

The book wrestles with two big questions: How have American emotions changed over time? And how has technology aided and abetted those changes? The study of the kinds of emotions an entire nation has experienced over time faces huge definitional challenges. Even looking at people who lived at roughly the same time, the feeling we now describe as “boredom” meant one thing to Thomas Jefferson, who counseled his daughter to avoid the “ennui” of her privileged life through mental activity; something else to James Williams, a 19th-century black American who described the “gloomy monotony” of slavery; and something else to the young female workers at the Lowell, Massachusetts, mills, who angled for seats near the windows so they could break up the repetition of their tasks with glances at the river.

And how do you even measure rates of something like boredom over time? Emotions are necessarily self-reported, and reporters are communicating not only their feelings but also the way they’ve been taught to feel about those feelings. The question of whether technology “causes” changes in the human heart is at least as knotty. “Technology alone does not determine feelings, but the larger culture, of which it is one part, undeniably shapes them,” is the best Matt and Fernandez can do. It’s a mess! But the mess is fascinating.

Example: The advent of accessible photography in the late 19^th century did not “make” us more vain, or more interested in presenting our lives to others in a favorable light. But over time, the democratization of access to cameras seems to have combined with a million other big and small factors to have the same effect. Domestic photographs from the 19^th century look weird to us because they’re so dark and sad, and the people are so unsmiling, Fernandez and Matt point out. In the 19^th century, Fernandez and Matt write, grinning was seen as something for (they quote communications scholar Christina Kotchemidova) “peasants, drunkards, children, and halfwits.” This is why the portraits in the cult-classic book Wisconsin Death Trip look so creepy to contemporary audiences. Historian Nancy West has made the argument that, in the course of its early advertising campaigns, Kodak taught Americans how to present themselves as happy. It wasn’t until the 20^th century that Americans learned to don that cheerful, “we’re doing great” look when cameras were around.