What makes specific marketing messages feel convincing while others fail to inspire trust, and why do some political slogans seem to linger in people’s minds more effectively than competing claims? Recent research from the University of California, San Diego’s Rady School of Management suggests that persuasion is shaped not only by whether people agree with a message, but by how confident they feel in making that judgment. The study highlights a surprisingly small linguistic detail — whether a word has an easy, obvious opposite — as a key factor influencing belief and confidence.

According to Giulia Maimone, who conducted the research during her doctoral studies at the Rady School of Management, effective communication goes beyond agreement alone. People continuously assess whether statements are true or false, but they also develop a sense of certainty about those decisions. That sense of confidence plays a critical role in how persuasive a message becomes. Language, the research shows, can subtly strengthen or weaken that certainty, helping to explain why some messages resonate more strongly than others.

The study, forthcoming in the Journal of the Association for Consumer Research, finds that messages often hinge on the types of words they use. In particular, the researchers focus on “reversible” words, which have apparent and readily accessible opposites, such as intense and mild, or guilty and innocent. When people encounter a claim framed with such words and disagree with it, they tend to replace the original term with its opposite mentally. This process differs from how people respond to words that lack a precise opposite.

This difference matters because rejecting a reversible word requires an additional mental step. Retrieving and substituting the opposite word demands more cognitive effort, which in turn reduces people’s confidence in their opposing belief. By contrast, when a word does not have an obvious opposite, people usually negate it by adding “not”, a more straightforward process that leaves them feeling more certain in their disagreement. As a result, messages using non-reversible words often provoke stronger resistance.

For marketers and political communicators, this creates a subtle strategic advantage. When a positive claim is framed with a reversible word, people who accept the message feel confident in their belief, while those who reject it tend to feel less optimistic about their counter-argument. Even disagreement, then, becomes softer. The wording does not necessarily change minds, but it weakens the confidence of opposition, increasing the overall persuasive power of the message.

The researchers tested these ideas both in controlled experiments and in a real-world field study involving Facebook advertisements. Across more than 1,000 participants, they found that language designed to generate higher confidence judgements led to greater engagement, including higher click-through rates. Together, the findings show that persuasion depends not only on what people believe, but on how firmly they believe it — and that carefully chosen words can quietly shape that certainty.

More information: Giulia Maimone et al, How Word Reversibility Impacts Judgment Confidence, Journal of the Association for Consumer Research. DOI: 10.1086/740066

Journal information: Journal of the Association for Consumer Research Provided by University of California – San Diego