New research from performance marketing firm RTB House shows that AI tools like Google AI Overviews and ChatGPT have overtaken both social media and traditional news outlets as the most trusted sources for shopping advice. The study surveyed 1,840 consumers across the U.S., U.K., France, and Japan, and reveals a paradox for marketers: While shoppers trust AI more, they also take longer to make purchase decisions.
Forty-two percent of U.S. consumers report that AI tools increase the time it takes to reach a final purchase decision. The reason is counterintuitive - AI surfaces more brands, products, and alternatives to consider, expanding the research phase rather than compressing it. Among U.S. Gen Z shoppers, that number rises to 48 percent.
AI overtakes TikTok and newspapers as a trust source
Among U.S. and international shoppers, leading AI tools now beat TikTok, Instagram, and Facebook for trustworthiness. They also outperform newspapers and major media outlets. The study found that 46 percent of U.S. Millennials have already purchased from a brand they discovered through AI this year.
But trust isn't evenly distributed. Google AI Overviews and ChatGPT hold a clear lead in trust, while Claude and Grok lag behind in both the U.S. and global markets.
AI extends the consideration window, doesn't shrink it
Fifty-nine percent of U.S. consumers said AI is good at surfacing brands they didn't previously know, with Gen X (61%) and Baby Boomers (62%) being among the groups most receptive to new brand discovery through AI. U.S. shoppers typically visit a website 4 to 6 times before completing a purchase, and AI stretches that window even further.
For marketers, this changes the competitive dynamic. "As AI expands the consideration window, competition is fiercer than ever," said Jaysen Gillespie, VP of Product Marketing & Analytics at RTB House.
Some millennials would let AI spend money for them
The trust extends beyond research and into delegation. Forty-two percent of U.S. Millennials said they would trust an AI agent with up to $250 for purchases if a seven-day return window is guaranteed. Without any return protection, 34 percent of Millennials were still comfortable with the arrangement. Human approval before checkout remains the most requested safeguard globally.
"For more than a decade, e-commerce growth was driven by buying attention on social feeds and optimizing for instant checkouts," Gillespie said. "This research proves that era is coming to an end. Consumers are turning to AI as a new engine, using it to evaluate and discover brands, conduct price comparisons, and conduct deeper research before they buy."
Why this matters for marketers
The study suggests that the traditional playbook - chase attention on social feeds, optimize for immediate conversion - is becoming less effective. Instead of trying to compress the path to purchase, the more realistic strategy is to treat the extended consideration window, combined with the head start it gives to brands that appear in AI shows. That means marketers need to invest in being discoverable through AI while also using on-site trust signals, ethical return policies, and relevant offers during the longer consideration cycle to win transactions. As Gillespie put it: "Our advice for modern marketers would be to take advantage of that extended window."
The full report "Consumers in the Age of Agentic AI" is available on the RTB house website.
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