We at Planet Money often scan new economic resesarch for interesting ideas or evidence about the economy or, more broadly, the world around us. Sometimes this research informs our podcasts. Sometimes they inspire newsletters or radio segments. But often these insightful gems are just left on our proverbial shelves gathering dust. And that inspired a recurring newsletter where we take them off the shelves and provide them to you.
Welcome to the latest installment of the Planet Money Econ Paper Roundup!
Today in the Planet Money newsletter, five recent papers that lit lightbulbs in our brains, and are maybe worth taking a look at.
Brain Rot Is Real?!
People have been talking about "brain rot" for a while. The basic idea is that consuming junk content — like watching TikTok videos or doomscrolling social media feeds — makes you dumber.
Last year, Oxford University Press actually named "brain rot" the "Oxford Word of the Year." They offer a more formal definition: "the supposed deterioration of a person's mental or intellectual state, especially viewed as the result of overconsumption of material (now particularly online content) considered to be trivial or unchallenging. Also: something characterized as likely to lead to such deterioration."
Notice Oxford's definition includes the qualifier supposed before deterioration. Until now brain rot has been more of a casual observation than something backed by hard evidence.
But a new, peer-reviewed study in The Quarterly Journal of Economics (a top econ journal) suggests brain rot is very real. The economists Panle Jia Barwick, Siyu Chen, Chao Fu and Teng Li find that students who frequently use smartphone apps see much worse outcomes. This isn't just because frequent app users might be different types of people to infrequent app users. The authors build the case that these bad outcomes are actually caused by the apps: they exploit the fact that roommates are randomly assigned, and roommates influence how much students use apps. The economists find that when student uses apps more, they spend less time studying, get less sleep, and are more often late to class. And, the economists find, frequent use of apps leads students to have significantly lower GPAs and even, eventually, lower wages. Ouch.
Turn off your phones, people!
Musk's Partisan Activism Seriously Damaged Tesla Sales
Progressives typically care more about climate change and policies aimed at protecting the environment. This long helped make them an important consumer base for Tesla's electric cars. But then something happened: Elon Musk, Tesla's CEO, started using his megaphone to support right-wing policies and candidates, and he alienated many of them big time.
It's pretty obvious that Musk's vocal partisanship hurt Tesla sales. But by how much?
A new working paper by economists Kenneth T. Gillingham, Matthew Kotchen, James A. Levinsohn and Barry J. Nalebuff crunches the numbers. They find that, "Without the Musk partisan effect, Tesla sales between October 2022 and April 2025 would have been 67-83% higher, equivalent to 1-1.26 million more vehicles." Holy moly.
Even more, the economists find, "Musk's partisan activities also increased the sales of other automakers' electric and hybrid vehicles 17-22% because of substitution, and undermined California's progress in meeting its zero-emissions vehicle target."
Numbers like these may make future CEOs think twice about being very vocal in partisan politics (in any direction) and alienating crucial customers.
The Effect Of European Wine Tariffs
During President Trump's first term, he imposed tariffs on a variety of goods, including, in 2019, European wine. A recent working paper from economists Aaron B. Flaaen, Ali Hortaçsu, Felix Tintelnot, Nicolás Urdaneta and Daniel Xu looks at the effect of these tariffs, including on U.S. consumers. Their answer: they weren't good for them. Tariffs caused wine sellers and distributors to raise their prices, so much so that ultimately consumers "paid more than the government received in tariff revenue."
One finding that's particularly noteworthy, considering we're still waiting to see the ultimate effect of Trump's wave of tariffs during his second term: the economists find it took roughly an entire year for the effects of wine tariffs to ping-pong their way through the wine distribution system and ultimately raise the retail prices paid by consumers.
A Reason Why Female Politicians May Underperform In Elections
There's a pretty well-known theory in economics known as the "glass cliff." The basic idea is that companies often pick female CEOs when their businesses are struggling, which sets them up for failure.
Well, there may be something similar in the political realm. A new working paper from economists Thomas Fujiwara, Hanno Hilbig and Pia Raffler tests a hypothesis that political parties systematically pick female candidates to compete in districts where their parties are less popular. They test this theory in Germany, with candidates for the German legislature (the Bundestag) across 11 elections.
Germany is an interesting place to look at because, in recent years, it's been known for strong female leadership. Angela Merkel served as Germany's chancellor for over 15 years. And it's ranked relatively high in global rankings for gender equality. Still there, the economists write, "women constitute only 35% of members of parliament."
What helps explain this? The economists find that "female underperformance" in German elections is "explained almost entirely by women running in districts where their party is less popular." They argue that "gendered party gatekeeping" is "an important driver of female underrepresentation" in the German legislature. And they suggest this is likely true in other nations.
An Estimate Of How Bad War Is For An Economy
In a new working paper, the economists Efraim Benmelech and Joao Monteiro look at the economic consequences of war, using a pretty cool dataset that covers "115 conflicts and 145 countries over the past 75 years."
They find that wars, on average, reduce national GDP by 13% and those countries fail to recover even after a decade. They find these economic downturns are worse in civil wars. They also find that wars explode deficits and significantly stoke inflation.
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So those are our five papers for this edition of the Planet Money Econ Paper Roundup. Not the cheeriest edition we must admit, but one that we hope can help you understand the world better.
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