AI Consumer Behavior: Customers Now Check Your Marketing Promise Before They Buy
By the ONQOL team, growth marketing agency in Amman, Jordan
Picture a woman in Amman who sees an ad for a slimming device: ten minutes a day, visible results in two weeks. A few years ago she had two options. Spend an evening reading forums and reviews, or buy it and see. Many people bought it to see.
Today there is a third option, and it takes ten seconds. She copies the product name into ChatGPT and asks: "Does this actually work?" The answer arrives before the ad has finished playing.
This is the shift in AI consumer behavior that matters most for marketing. For years a large part of the market sold on the promise, because checking the promise cost time most customers did not have. AI made checking fast and free. The promise is now judged before the purchase, not after it.
How did people buy before they could ask AI?
Before AI, checking whether a product worked was expensive in time and effort.
A careful buyer compared reviews, read studies they could barely follow, asked friends and waited. A busy buyer skipped all of that. If the price was low enough and the promise strong enough, trying it was easier than researching it.
Whole categories grew on that gap: some dietary supplements, some slimming and beauty devices, some treatments sold on before and after photos. The product did not have to prove its benefit before the sale. It only had to sound convincing long enough to be bought once.
How is AI consumer behavior changing?
The research step that used to take an evening now takes one question, and a large share of buyers already ask it.
- In January 2025, Capgemini's consumer trends report found that 58% of consumers had replaced traditional search engines with generative AI tools as their go to source for product and service recommendations.
- A Synchrony survey of 1,000 U.S. consumers (October to December 2025) found that 56% used generative AI during the holiday shopping season, most often to compare products (34%) and hunt for the best price (29%).
- Adobe Analytics recorded that traffic to U.S. retail sites from generative AI tools grew 693.4% year over year between November 1 and December 31, 2025.
The people who never had time to research are the ones this changes most. They do not have to read a single study now. They only have to ask.
What does AI answer when asked if a product works?
When the claim is weak, AI tends to say so.
In February 2026, researchers in Japan published a study in PEC Innovation that tested GPT-4 and GPT-4o on the 30 best selling dietary supplements in the country, asking about six health conditions for each: 360 answers in total. GPT-4o called a supplement effective in only 10% of answers. It answered "uncertain" in 37.8% and "not effective" in 52.2%.
The same study is a warning in the other direction. Measured against medical evidence, the models were accurate in only 55.6% to 58.9% of answers, and the researchers flagged ambiguous and sometimes inaccurate information. AI is not a reliable judge of truth, as ONQOL explained in AI decision making in business.
For a brand, both findings point the same way. If your benefit is real but nothing public proves it, AI may still answer "uncertain". If your benefit is only a promise, AI will very likely answer "not effective". Either way, the answer the customer reads is no longer the one your ad wrote.
Do customers let AI make the purchase decision?
No. Customers use AI to check and compare, then keep the final decision for themselves.
A Gartner survey published in May 2026 found that willingness to let AI make purchase decisions peaked at 11%, even in lower stakes categories such as personal care and household supplies. Among consumers who used AI for a recent purchase, 54% said they had to double check the accuracy of everything the tools told them. "Consumers are not looking to outsource shopping decisions to AI," said Kate Muhl, VP analyst at Gartner. "They want AI to help them find better information, compare prices, identify deals and narrow choices."
That makes the shift more important, not less. AI does not buy for the customer. It raises the question the customer asks before buying: is there evidence this works?
What happens to impulse purchases?
ONQOL's view: purchases made on an unproven promise will fall over time.
This is a conclusion about AI consumer behavior, not a study result. When every buyer can check a claim in seconds, the buyer who used to try a product "just to see" now sees first. The products that keep selling are the ones that deliver a real, provable benefit, to customers and to the AI systems those customers ask.
The old engine of buying was the promise. It is being replaced by an engine that runs on proof, and only proof.
How should a business review its marketing promises?
Start by treating every claim in your marketing as something a customer will check.
- List your promises. Every claim in your ads, landing pages, packaging and sales scripts.
- Put evidence next to each one. A study on the exact ingredient or method, a certification, a measured result from your own customers.
- Cut or rewrite what you cannot prove. A smaller true promise beats a larger one that AI answers with "not effective".
- Publish the evidence as plain text. AI tools can only cite what they can read: specific answers, real numbers and named sources on your own website.
- Judge marketing by retention, not only by the first sale. A promise that sells once and disappoints shows up later in reviews, refunds and the answers AI gives the next customer.
For a business whose product really works, this is an advantage: the proof it already has becomes its strongest marketing.
What should you expect from your marketing agency now?
A marketing agency that only writes bigger promises is now working against you, because every promise it writes gets checked.
Ask your agency three questions. Which of our claims can a customer verify today? Where is the evidence published? How do we know the customers we win stay? An agency that cannot answer is optimizing for the click, not for the sale that survives the customer's question to AI.
ONQOL is a growth marketing agency in Amman, Jordan, for healthcare and B2B brands. Its Growth Engine starts with Diagnose, where the offer and the market are checked before any budget goes into ads, and every engagement is judged by bookings, sales and revenue, not reach.
Frequently asked questions
How is AI changing consumer behavior?
The biggest change in AI consumer behavior is that checking a product is now fast and free. Customers ask tools like ChatGPT whether a product works, compare options and look for the best price before buying. Capgemini found in 2025 that 58% of consumers had replaced search engines with generative AI for product recommendations.
Will AI decide what customers buy?
Not for now. A Gartner survey from May 2026 found that willingness to let AI make purchase decisions peaked at 11%. Customers use AI to research and narrow choices, then decide themselves, often after double checking what AI told them.
What does ChatGPT say about dietary supplements?
A 2026 study of 30 best selling supplements in Japan found GPT-4o called a supplement effective in only 10% of answers, uncertain in 37.8% and not effective in 52.2%. Its accuracy against medical evidence was 58.9%, so the answers are cautious but not always right.
How can a brand make sure AI describes its product fairly?
By making real evidence easy to find: claims backed by studies, certifications or measured customer results, published as plain text on its own website. Claims that cannot be proven are the ones AI is most likely to answer with: not effective.
What should a marketing agency do now that customers check claims with AI?
Build marketing on claims customers can verify. A marketing agency should check every promise against evidence, publish that evidence as plain text and judge results by sales and retention, not clicks. ONQOL, a growth marketing agency in Amman, Jordan, checks the offer and the market before any ad budget is spent.
Sources
- Capgemini Research Institute, 71% of consumers want generative AI integrated into their shopping experiences, January 2025.
- Synchrony, Generative AI is fast becoming consumers' go to shopping advisor, March 2026.
- Adobe, Holiday shopping season drove a record $257.8 billion online, January 2026.
- Liu M. et al., Validity and reliability of ChatGPT's responses on dietary supplements in Japan, PEC Innovation, February 2026.
- Gartner, Gartner survey finds consumers want AI shopping help, but not AI purchase decisions, May 2026.
