• Home
  • Latest
  • Fortune 500
  • Finance
  • Tech
  • Leadership
  • Lifestyle
  • Rankings
  • Multimedia
AI

Experienced software developers assumed AI would save them a chunk of time. But in one experiment, their tasks took 20% longer

Sasha Rogelberg
By
Sasha Rogelberg
Sasha Rogelberg
Reporter
Down Arrow Button Icon
Sasha Rogelberg
By
Sasha Rogelberg
Sasha Rogelberg
Reporter
Down Arrow Button Icon
July 20, 2025, 7:33 AM ET
A man works at a table with a laptop on it. A projector in the background displays code.
In one recent study, AI hampered the productivity of software developers.Getty Images
  • AI tools don’t always boost productivity. A new study from Model Evaluation and Threat Research found that when 16 software developers were asked to perform tasks using AI tools, the they took longer than when they weren’t using the technology, despite their expectations AI would boost productivity. The research challenges the dominant narrative of AI driving a workplace efficiency boost.

It’s like a new telling of the “Tortoise and the Hare”: A group of experienced software engineers entered into an experiment where they were tasked with completing some of their work with the help of AI tools. Thinking like the speedy hare, the developers expected AI to expedite their work and increase productivity. Instead, the technology slowed them down more. The AI-free tortoise approach, in the context of the experiment, would have been faster. 

Recommended Video

The results of this experiment, published in a study this month, came as a surprise to the software developers tasked with using AI—and to the study’s authors, Joel Becker and Nate Rush, technical staff members of nonprofit technology research organization Model Evaluation and Threat Research (METR).

The researchers enlisted 16 software developers, who had an average of five years of experience, to conduct 246 tasks, each one a part of projects on which they were already working. For half the tasks, the developers were allowed to use AI tools—most of them selected code editor Cursor Pro or Claude 3.5/3.7 Sonnet—and for the other half, the developers conducted the tasks on their own.

Believing the AI tools would make them more productive, the software developers predicted the technology would reduce their task completion time by an average of 24%. Instead, AI resulted in their task time ballooning to 19% greater than when they weren’t using the technology.

“While I like to believe that my productivity didn’t suffer while using AI for my tasks, it’s not unlikely that it might not have helped me as much as I anticipated or maybe even hampered my efforts,” Philipp Burckhardt, a participant in the study, wrote in a blog post about his experience.

Why AI is slowing some workers down

So where did the hares veer off the path? The experienced developers, in the midst of their own projects, likely approached their work with plenty of additional context their AI assistants did not have, meaning they had to retrofit their own agenda and problem-solving strategies into the AI’s outputs, which they also spent ample time debugging, according to the study. 

“The majority of developers who participated in the study noted that even when they get AI outputs that are generally useful to them—and speak to the fact that AI generally can often do bits of very impressive work, or sort of very impressive work—these developers have to spend a lot of time cleaning up the resulting code to make it actually fit for the project,” study author Rush told Fortune.

Other developers lost time writing prompts for the chatbots or waiting around for the AI to generate results.

The results of the study contradict lofty promises about AI’s ability to transform the economy and workforce, including a 15% boost to U.S. GDP by 2035 and eventually a 25% increase in productivity. 

But Rush and Becker have shied away from making sweeping claims about what the results of the study mean for the future of AI.

For one, the study’s sample was small and non-generalizable, including only a specialized group of people to whom these AI tools were brand new. The study also measures technology at a specific moment in time, the authors said, not ruling out the possibility that AI tools could be developed in the future that would indeed help developers enhance their workflow.

The purpose of the study was, broadly speaking, to pump the brakes on the torrid implementation of AI in the workplace and elsewhere, acknowledging more data about AI’s actual effects need to be made known and accessible before more decisions are made about its applications.

“Some of the decisions we’re making right now around development and deployment of these systems are potentially very high consequence,” Rush said. “If we’re going to do that, let’s not just take the obvious answer. Let’s make high-quality measurements.”

AI’s broader impact on productivity

Economists have already asserted that METR’s research aligns with broader narratives on AI and productivity. While AI is beginning to chip away at entry-level positions, according to LinkedIn chief economic opportunity officer Aneesh Raman, it may offer diminishing returns for skilled workers such as experienced software developers.

“For those people who have already had 20 years, or in this specific example, five years of experience, maybe it’s not their main task that we should look for and force them to start using these tools if they’re already well functioning in the job with their existing work methods,” Anders Humlum, an assistant professor of economics at the University of Chicago’s Booth School of Business, told Fortune.

Humlum has similarly conducted research on AI’s impact on productivity. He found in a working study from May that among 25,000 workers in 7,000 workplaces in Denmark—a country with similar AI uptake as the U.S.—productivity improved a modest 3% among employees using the tools. 

Humlum’s research supports MIT economist and Nobel laureate Daron Acemoglu’s assertion that markets have overestimated productivity gains from AI. Acemoglu argues only 4.6% of tasks within the U.S. economy will be made more efficient with AI.

“In a rush to automate everything, even the processes that shouldn’t be automated, businesses will waste time and energy and will not get any of the productivity benefits that are promised,” Acemoglu previously wrote for Fortune. “The hard truth is that getting productivity gains from any technology requires organizational adjustment, a range of complementary investments, and improvements in worker skills, via training and on-the-job learning.”

The case of the software developers’ hampered productivity points to this need for critical thought on when AI tools are implemented, Humlum said. While previous research on AI productivity has looked at self-reported data or specific and contained tasks, data on challenges from skilled workers using the technology complicate the picture.

“In the real world, many tasks are not as easy as just typing into ChatGPT,” Humlum said. “Many experts have a lot of experience [they’ve] accumulated that is highly beneficial, and we should not just ignore that and give up on that valuable expertise that has been accumulated.”

“I would just take this as a good reminder to be very cautious about when to use these tools,” he added.

Join us at the Fortune Workplace Innovation Summit May 19–20, 2026, in Atlanta. The next era of workplace innovation is here—and the old playbook is being rewritten. At this exclusive, high-energy event, the world’s most innovative leaders will convene to explore how AI, humanity, and strategy converge to redefine, again, the future of work. Register now.
About the Author
Sasha Rogelberg
By Sasha RogelbergReporter
LinkedIn iconTwitter icon

Sasha Rogelberg is a reporter and former editorial fellow on the news desk at Fortune, covering retail and the intersection of business and popular culture.

See full bioRight Arrow Button Icon

Latest in AI

Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025

Most Popular

Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Rankings
  • 100 Best Companies
  • Fortune 500
  • Global 500
  • Fortune 500 Europe
  • Most Powerful Women
  • Future 50
  • World’s Most Admired Companies
  • See All Rankings
Sections
  • Finance
  • Leadership
  • Success
  • Tech
  • Asia
  • Europe
  • Environment
  • Fortune Crypto
  • Health
  • Retail
  • Lifestyle
  • Politics
  • Newsletters
  • Magazine
  • Features
  • Commentary
  • Mpw
  • CEO Initiative
  • Conferences
  • Personal Finance
  • Education
Customer Support
  • Frequently Asked Questions
  • Customer Service Portal
  • Privacy Policy
  • Terms Of Use
  • Single Issues For Purchase
  • International Print
Commercial Services
  • Advertising
  • Fortune Brand Studio
  • Fortune Analytics
  • Fortune Conferences
  • Business Development
About Us
  • About Us
  • Editorial Calendar
  • Press Center
  • Work At Fortune
  • Diversity And Inclusion
  • Terms And Conditions
  • Site Map
  • Facebook icon
  • Twitter icon
  • LinkedIn icon
  • Instagram icon
  • Pinterest icon

Latest in AI

NewslettersCIO Intelligence
WPP’s CTO says AI is reshaping advertising. But creative judgment needs to remain in human hands
By John KellJanuary 21, 2026
18 hours ago
Future of Workskills
‘AI adoption is accelerating, but confidence is collapsing’: The more workers use AI, the less they trust it. Baby boomers show a 35% drop
By Jake AngeloJanuary 21, 2026
19 hours ago
US President Donald Trump jokes with Meta CEO Mark Zuckerberg (L) as he hosts tech leaders for a dinner in the State Dining Room of the White House in Washington, DC, on September 4, 2025.
AIMeta
Trump says Mark Zuckerberg showed him a ‘Manhattan-sized’ AI data center
By Eva RoytburgJanuary 21, 2026
19 hours ago
Illustration of Claude 4 open on a smartphone
AIAnthropic
Anthropic rewrites Claude’s guiding principles—and entertains the idea that its AI might have ‘some kind of consciousness or moral status’
By Beatrice NolanJanuary 21, 2026
19 hours ago
Jensen Huang
SuccessCareers
Six-figure plumbing and construction jobs are coming, Nvidia CEO Jensen Huang says—as AI data centers need to be built
By Preston ForeJanuary 21, 2026
20 hours ago
huang
InvestingDavos
Jensen Huang says AI bubble fears are dwarfed by ‘the largest infrastructure buildout in human history’
By Nick Lichtenberg and Beatrice NolanJanuary 21, 2026
20 hours ago

Most Popular

placeholder alt text
AI
Elon Musk says that in 10 to 20 years, work will be optional and money will be irrelevant thanks to AI and robotics
By Sasha RogelbergJanuary 19, 2026
3 days ago
placeholder alt text
Economy
Jamie Dimon says he’d have no issue paying higher taxes if it actually went to people who need it. Right now it just goes to the Washington ‘swamp’
By Eleanor PringleJanuary 21, 2026
19 hours ago
placeholder alt text
Politics
Jamie Dimon tells Davos: ‘You didn’t do a particularly good job making the world a better place’
By Eleanor PringleJanuary 21, 2026
20 hours ago
placeholder alt text
Personal Finance
Current price of silver as of Tuesday, January 20, 2026
By Joseph HostetlerJanuary 20, 2026
2 days ago
placeholder alt text
Economy
Scott Bessent insists he’s ‘not concerned at all’ about investors selling America—despite the fact it’s unraveled tariffs before
By Eleanor PringleJanuary 21, 2026
1 day ago
placeholder alt text
Success
Billionaire Marc Andreessen spends 3 hours a day listening to podcasts and audiobooks—that’s nearly an entire 24-hour day each week
By Preston ForeJanuary 20, 2026
2 days ago

© 2026 Fortune Media IP Limited. All Rights Reserved. Use of this site constitutes acceptance of our Terms of Use and Privacy Policy | CA Notice at Collection and Privacy Notice | Do Not Sell/Share My Personal Information
FORTUNE is a trademark of Fortune Media IP Limited, registered in the U.S. and other countries. FORTUNE may receive compensation for some links to products and services on this website. Offers may be subject to change without notice.