My wife stared at me in shock as I ripped open the package. The FedEx driver hadn’t even made it back to his truck as I held the item up overhead like a trophy. Fumbling for words, she asked: “Why on earth did you buy a Speedo … with dinosaur tear-away trunks?”
Honestly, I couldn’t remember. Maybe it was for a social media skit? Maybe I was planning on making her laugh? Or maybe I was just a “victim” of an online ad that showed me the wrong message at the right time.
Scroll on social media for even 30 seconds, and your brain is already a little more tired than it was before. And in that mentally foggy state, you become more open to ads that just tell you what to buy – “The facts make it clear, we’re the best!” – than to ads that invite you to draw your own conclusion.
I’m a professor of advertising who has spent years studying how social media affects consumer behaviour. And my recent research underscores how the mental tax of processing information, or “cognitive load,” changes the way people respond to product claims from brands.
Explicit versus implicit pitches
Joined by fellow researchers Stan Li and Bixuan Sun, I ran three experiments testing how people processed online ads for eco-friendly products.
In each study, half the participants first spent time on Instagram, scrolling for 30 seconds, while the other half did not. Everyone then viewed an Instagram post from a sustainable brand.
Participants in the first study saw an ad for laundry detergent sheets; the second, an eco-friendly phone case; and the third, a reusable water bottle. Each ad laid out several environmental facts about the product.
The only thing we changed was the last line of the caption. Half the participants saw an implicit conclusion: “Who makes the best, most sustainable detergent? Here are the facts, now decide for yourself.” The other half saw an explicit conclusion: “Who makes the best, most sustainable detergent? The facts make it clear – it’s TruEarth!!”
What emerged was a consistent pattern: Under normal conditions, without cognitive load, participants preferred the implicit conclusion. In other words, they wanted to think for themselves.
But when cognitive load was introduced just through scrolling on Instagram – something half of all U.S. adults do every day – participants preferred the ad that explicitly told them to buy the featured product because it was “the best.”
We found that credibility explained this phenomenon. When consumers were under cognitive load and preferred the ads with explicit conclusions, it wasn’t because they consciously noticed that the ad was telling them what to do. Nobody would ever admit to being that impressionable. Rather, they preferred clear and bold conclusions because those claims made the brands seem more credible.
I think this tracks with the way we look at people, too. Under normal conditions, someone who’s bossy or pushy can come across as arrogant and annoying. But when we’re stressed or in a crisis situation, that same assertiveness can be reassuring.
The puzzle is that sustainability claims are challenging for advertisers. You can’t taste “50% lower emissions” or see “ethically sourced” the way you can judge a coffee’s flavour or a shirt’s fit. Sometimes, you have to take the brand’s word for it. That makes credibility especially important. No brand wants to be accused of greenwashing.
The cost of cognitive load
Normally, when people have the mental bandwidth to think something through, they prefer to reach their own conclusions and are less swayed by superficial information. It feels more like their own opinion and less like an order or strong suggestion.
Imagine one friend recommending a restaurant by listing dishes they loved and letting you decide whether it sounds good, while another flatly declares: “You have to go to this restaurant, it’s the best.” We all like to think of ourselves as rational consumers who make up our own minds about what to do, say, and purchase – even if this isn’t true.
And when we have the time, patience and mental energy to really think through a purchase decision, we may prefer ads that let us draw our own conclusion, based on the facts.
But if cognitive load is in play, the calculation flips. Picture trying to evaluate that same restaurant recommendation from your friend while responding to your boss’s texts, half-listening to a podcast and keeping an eye on a pot of pasta on the stove, all at the end of a long week. You just don’t have the spare mental effort to assess the evidence yourself.
In that state, a friend who just tells you to trust them is easier to believe. The confidence sends a signal that they know what they’re talking about, and the extra clarity is a relief rather than an imposition.
That’s essentially what’s happening when people scroll on social media. Their attention is split across a feed of friends, acquaintances, advertisements, family, celebrities, influencers, brands and strangers – all competing for the same limited mental resources. When a sustainability-themed ad follows that scroll, spelling out “it’s us” rather than “you decide,” it doesn’t come across as pushy. It comes across as confident and trustworthy, precisely because users don’t have the spare capacity to work it out on their own.
If you’ve seen the 1991 movie “Father of the Bride,” you’ll know that Steve Martin’s character is a loving father and that Martin Short is not shy. But weddings are stressful. And when Martin’s cognitive load increases to his breaking point, he makes a bad decision:
And this won’t surprise you: Every consumer thinks they are more rational and less emotional than everybody else.
Of course, this could be true. Sometimes. But even the most rational person has “foggy brain” now and then. Whether you’re an early bird or a night owl, our research emphasises the importance of being in the right mental state when buying online, especially for big purchases.
The times when your cognitive load or brain fog is higher – late afternoon, later in the week, or right before a big event – are not when you should be making important financial decisions. And definitely don’t buy anything on a Friday afternoon at 4 p.m.
Instead, you should wait until the following morning, when you can think clearly.
When credibility backfires
While an explicit product claim works because it signals credibility, it can quickly tip into what looks like false advertising when it’s not backed by evidence. Worse, it could trigger a boomerang effect where you end up hating the ad or brand.
In our case, we only tested claims paired with real and specific facts, such as whether the goods used recycled materials and had verified certifications or quantified emissions cuts. But a brand that states its conclusion boldly without backing it up may find that the same trick backfires. And scepticism, once triggered, is hard to undo.
Our finding does have limitations for now. While we studied sustainability messaging in part because it’s uniquely hard to verify on the spot, it’s unclear whether the same effect about explicit messaging shows up for other claims that can be dense and hard to check, such as ads promoting health benefits or offering financial products. We all know how easy it is for false or misleading messages to go viral and do plenty of damage before their claims can be fact-checked.
But for now, if you’re scrolling, half-distracted, and a brand confidently declares itself the best, remember that confidence might be working on you exactly because your guard is down.
So unless you want to experience buyer’s remorse, consider holding off on that late-night purchase for now. Wait until the next morning.
- is an Associate Professor of Advertising and Public Relations, University of Tennessee
- This article first appeared in The Conversation
1 Comment
I went through something similar with down guard recently, and I wish I had found this article sooner. Your explanation of guard would have saved me quite a bit of trial and error.