Before transferring to UC Berkeley, Saul Munn wrote dozens of flash cards to quiz himself on the city’s layout. “When I moved, I just instantly knew my way around,” said the senior, 22, who studies philosophy. “I never use Google Maps to drive.” Even with all the time he spent reviewing, he thinks, “I’m actually probably still saving time.”

The digital Berkeley geography flash cards are just a fraction of Munn’s collection of more than 2,200. He uses flash cards for memorizing Robert Frost poems and learning Chinese, but also to remind himself to reflect on what he’s grateful for, like the high he gets after working out. He reviews his cards daily, keeping track of them using the open-source flash card application Anki.

Munn is part of a small but growing subculture that uses digital flash cards — or “spaced repetition memory systems (opens in new tab)” — to sharpen thinking and retain information. Interest in the practice has increased dramatically since 2024, when podcaster Dwarkesh Patel started tweeting (opens in new tab) about his use of flash cards as complements to reading. Stripe founder Patrick Collison, Tim O’Reilly of O’Reilly Media, San Francisco street artist fnnch, and Quizlet founder Andrew Sutherland are among the financial supporters of Orbit (opens in new tab), a spaced repetition education tool developed by Andy Matuschak, a Berkeley-based memory systems researcher. Spaced repetition is the backbone of software used by Alpha Schools, the tech-backed private school network with 13 U.S. locations.

In the Bay Area, Matuschak said, “I know more than a hundred people who use spaced repetition in very broad and creative ways.”

The embrace of memory systems aligns with Silicon Valley’s zeal for optimization and the incremental improvements that can be gained from taking peptides or eating protein or soaking in ice water. It also comes at a time when many are fretting about what social media and AI are doing to cognition, a sinking feeling that New York magazine dubbed “the stupiding of the American mind (opens in new tab).” A spate (opens in new tab) of (opens in new tab) papers (opens in new tab) have drawn connections between increased AI use and a decreased ability to think critically, though researchers caution that their findings are preliminary. Regardless, the trajectory is not bright: From 2006 to 2018, one study found (opens in new tab), the average IQ score in the United States declined.

While many outsource their thinking to machines, practitioners of spaced repetition do the opposite. The digital flash card systems quiz users on information, delaying the next review for each correct question and increasing the frequency of incorrect ones. Users report becoming obsessive about retaining information. 

“I got hooked,” said Eleanor Berger, an AI business consultant with an Anki deck of about 23,000 cards. “Anything I ever thought I should probably try to remember is there.” 

For those in the Anki community, the practice of memorization is central to complex understanding, problem-solving, and creativity. Their founding document may be “Augmenting Long-Term Memory (opens in new tab),” a 2018 blog post by quantum physicist Michael Nielsen, who argues that flash cards work because of the “chunking” effect. When chess masters look at a chess board, they process memorized “chunks” of moves rather than individual maneuvers of rooks and pawns. This adds a shortcut to their working memory, letting them focus on higher-level problems. Nielsen posits that we can do this in all areas of our lives, improving cognition and creativity.

By using flash card apps like Anki — which is free on desktops and Android phones but costs a one-time $25 fee on the iPhone — to encourage this “chunking,” memory becomes no longer passive but an active choice.

Devotees of spaced repetition have seen this payoff. “It’s made me functionally smarter,” said Berger. “I don’t think my intelligence increased, but my ability to use it actually improved.” 

Power users are constantly searching for new ways to bolster their practice. Matuschak uses his homebrewed flash card software to quiz himself on friends’ birthdays and their children’s names. San Francisco software engineer Sameer Ismael uses cards to remind himself to contemplate mistakes he has made in past relationships. He likes to engage with cards that have open-ended questions that push him to ponder his decisions. “What is the fundamental root cause [of the problem]? Are you making the same mistakes right now? How would you want to rectify that?”

Until recently, the spaced repetition community operated informally online, through email threads and Discord servers. Last year, Munn was inspired to bring together a “bunch of interesting, fascinating nerds [who talk] to each other online but don’t know each other in person.” In September, he organized Memoria, a one-day conference in Berkeley dedicated to memory systems, which drew around 120 attendees.

Afterward, Munn created flash cards to match attendees’ names to their faces. He has since run into a few of them on the streets of Berkeley. He likes to say hi. “I’ll be like, ‘Oh, you’re Norm, right?’” They often don’t immediately recognize him.

Following Memoria, Munn and Ismael hosted other meetups at Bay Area hacker spaces. At the coworking space Mox in the Mission, they hosted a gathering that, according to Ismael, “was trying to be a bit more serious about things” and included only “people who really wanted to advance at the craft.”

For Anki’s most dedicated users, flash cards transcend the pure utility of making one smarter. Munn describes it as a “deeply beautiful and potentially transformative piece of tech that can be very core to your soul.”

The calculus of whether flash cards can really make one smarter changes in a world where AI might surpass human abilities. But Anki users don’t think they’ll ever stop using the cards. “Some of the things I’m learning because they’re useful, and other things I’m learning because I enjoy thinking about them,” Munn said. “It sure as hell isn’t going to be the case that AIs replace that.”