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Key points
- Vagueness is a fundamental feature of much of human communication, from promises to advertising.
- New research shows that people prefer vagueness in order to save time, but this can come at a possible cost.
- Tune into the vagueness of a misleading promise to gain greater knowledge of who and what to believe.
A friend says “We’ll talk later,” or “I’ll call you soon.” Someone you’re supposed to meet is going to be late: “I’m on my way.” As unsatisfying as such statements can be, for some reason they work. You accept these vague promises without wondering if they'll ever come to pass.
Similarly, advertising slogans, from tech companies to political messages, come packaged with similar room for interpretation. Nike promises that you can, with their products, “Just Do It.” Just as memorable was the “Yes We Can" campaign ad. No one stops and thinks “Do what?” or “Can what?” much less “How?” These campaigns are as successful as they are vague. Their massive popularity suggests that the less specific the promise, the better.
The Vagueness of Persuasive Messages
In their scan of the media environment, Roma Tre University’s Giorgia Mannaioli and colleagues (2024) note that vagueness in communication isn't limited to these generic promises. Instead, it “is intrinsic to the linguistic code and arguably represents the default condition in everyday communication.” You might hear a person described as “tall” and be satisfied with this description, even though it begs the question, “Taller than what or who?” This common way of speaking (rather than saying the person is 6 feet 4 inches) is generally acceptable, the authors note, because at least it is “good enough” to give you an idea of the person’s stature. It’s enough information for you to compare the actual person, when you meet them, with their description.
However, vagueness also carries with it the potential to mislead the person who receives the communication when there is no such obvious basis for judging. “Marked vagueness,” Mannaioli et al. observe, applies to those vague promises that you'll never be able to test against reality. They are “neither completely verifiable nor falsifiable.” And yet, it is these statements that the authors maintain have the greatest power to persuade.
Thinking back on those two advertising messages, they fit marked vagueness criteria not only because they can never be proved or disproved, but because “every single receiver can interpret vague expressions as referring to anything they want.” Vague messages also use modifiers such as “more than,” “everything,” “many,” and “some.” They carry with them an implicit meaning rather than an explicit one. Therefore, like a projective test, people put their own meanings into them. Having done so, the message recipients believe that it was their own idea in the first place. After all, you know what you can “do," and that's what you imagine the ad means to you (run, jump, walk, or whatever). Putting the icing on the cake is the “egocentric bias,” in which you trust what you believe was your own conclusion
Why Does Vagueness Work?
The theory underlying the Tre University study is vagueness taps into people’s natural tendency to process information as quickly as possible in the shallowest and easiest way possible; the “now or never bottleneck” in language processing. You’ve got so many messages coming in from everywhere that there’s practically no time to fact-check all of them, so you accept, again using their words, “good enough” communication. This desire to process quickly at the expense of accuracy fits with what the authors call the “cost reduction hypothesis." You'd rather fast-think than slow-think because it takes less mental work.
To test the idea that people prefer vagueness because it’s so easy and quick to process, the authors set up an online experiment in which their 315 participants (average age 34 years old) were compared in their reading times of statements varying in vagueness along two dimensions: the provision of context and the degree of precision of the message. Here are examples of each type of statement (context refers to the second sentence and precision to the third in each example; italics added for illustration):
Non-precising context ("many," "few"); vague target ("some"):
Francesco is setting the table for his brother’s birthday party. There will be many guests and on the table there are few glasses. Francesco goes into the kitchen and takes some glasses.
Precising context ("ten," "eight"); vague target ("some"):
Francesco is setting the table for his brother’s birthday party. There will be ten guests and on the table there are eight glasses. Francesco goes into the kitchen and takes some glasses.
Precising context ("ten," "eight"); precise target ("two"):
Francesco is setting the table for his brother’s birthday party. There will be ten guests and on the table there are eight glasses. Francesco goes into the kitchen and takes two glasses.
To ensure that participants actually read the statements, they received questions about each one, such as, “Whose birthday was it?”
As you can see from these examples, once an exact number becomes provided, you have to stop and do some mental arithmetic as you figure out whether Francesco is doing the right thing. There's no arithmetic involved in the vaguest condition, the non-precising context and vague target. "Many," "some," and "few" are all you need to think about. There's your cost reduction.
Turning to the results, the non-precising/vague target condition produced the fastest reading time, consistent with the cost reduction hypothesis. Participants didn’t seem to pause and contemplate the meaning of the vague statements. As the authors suggest, vague statements stimulate “top-down” processing. You form an impression of what these statements mean, not bothering to look for any kind of deeper meaning or possible inconsistency: Vagueness works “by potentially diverting attention from questionable content details.” Did Francesco provide enough glasses in that first scenario? Probably. You don’t need to bother figuring out the details.
Moving From Vagueness to Specificity
Now that you know how easy it is to slip into the vague meanings that someone provides you without stopping to think or question, the next step is to figure out how to deepen your own cognitive processing. This is a good time in the U.S. to look at all the promises in political ads and see how easily you’re lured by the implicit meanings they try to create. You may already have your mind made up on your candidates, but it can be entertaining to see just how far they go on the vagueness dimension. From a practical standpoint, those ads that try to lure you into buying a product deserve a closer peek behind the curtain of vagueness to see if there's any there there.
When it comes to the vagueness of promises made by people in your daily life, similarly, it may be worth pressing a bit more on the details of phrases such as “soon” or “later.” Although you don’t want to seem tactless or rude, it may be worth it for your own peace of mind to have some kind of assurance of what they mean. If vagueness is indeed the “default” mode of communication, they may not even realize that they’re failing to give you the information you’d like to have to alleviate your worries.
To sum up, knowing about this important subtlety of communication can help you gain a greater understanding of how easy it is to be persuaded. Going “deep” may take longer when it comes to thinking, but your decision will be better as a result.
References
Mannaioli, G., Ansani, A., Coppola, C., & Lombardi Vallauri, E. (2024). Vagueness as an implicit-encoding persuasive strategy: An experimental approach. Cognitive Processing, 25(2), 205–227. 10.1007/s10339-023-01171-z
