The Truth Effect

You’ve probably heard the saying “blind as a bat.” Few would dispute the statement, yet it is entirely false.¹ (See the real story below.) We believe in the truth of many claims simply because we’ve heard them before and haven’t thought much about them. Marketing professionals call this condition the “Truth Effect.”

Truth Effect study

Researchers conducted three experiments exposing 237 subjects to an equal number of true and false advertising claims over the course of two sessions. Subjects saw some claims only in the first session, some only in the second session and some in both sessions. In each experiment, one group of subjects was asked to gauge the truth or falsity of the claims on a seven-point scale from “definitely false” (1) to “definitely true” (7). Another group rated whether the messages were easy to understand, from “difficult to understand” (1) to “very easy to understand” (7). In session two, all subjects were additionally asked to judge whether they had previously seen the item in the earlier session (yes or no). From the results, researchers determined claims heard more than once were more believable — whether these claims were actually true or false.²

Studies show frequency of repetition increases the believability of simple advertising messages.

EXECUTIVE SUMMARY

• The more often you expose your audience to your message, the more likely they are to believe the message is true (especially in the absence of claims to the contrary), regardless of whether the claim is true or false.

• Complex messages increase audience involvement. However, they lower the believability of your claims and lessen the Truth Effect.

• More complex feature/benefit messages should be reserved for brochures, websites and materials used closer to the actual buying decision.

• In the face of competitive claims, increased frequency can help advertisers maintain and foster believability of their own simple message.

Understanding the Truth Effect

Most people reading the introduction accept the claim as true, but it is entirely false. Bats have good eyesight, and some bats have exceptional vision, three to four times better than humans.¹

However, many of us still believe that bats are blind — and our belief illustrates the two major tenets of the Truth Effect:

1. Repetition leads to belief, regardless of the truth or falsity of the statement. We’ve heard over and over that bats are blind — therefore, it must be accurate.
2. “Low involvement” fosters belief. Unless we’re chiropterologists (scientists who study bats), our involvement with bats is probably low. We don’t care much about their eyesight and have likely never heard evidence disproving the myth that they’re blind.

Recognition of the claim is a critical element of the Truth Effect, which suggests the importance of consistency in advertising. Your audience must recognize your message for you to get the benefit of the Truth Effect. Repetition and consistency, even within the same forum — for example, two ads for your product in the same issue of a magazine — have been proven to enhance the Truth Effect.⁴

Conclusion: Keep it simple

In the study cited on page one, higher involvement with advertising claims led to greater skepticism. When participants in the study were asked to consider whether claims were actually true or false, they became far more critical.

Of course, your prospects will need to compare the relative merits of your product and competitors’ products when making a buying decision. However, prospects have to believe in you before they’ll even consider buying from you. Simply exposing prospects to claims is sufficient to increase their belief in related statements they hear later.⁵

The Truth Effect, suggests you should use simple, attention-getting claims in your advertising to foster believability. More complicated features and benefits should be left to brochures, websites and other sales materials closer to your prospect’s actual buying decision. By keeping advertising simple and letting sales materials fill in the details, your communications work harder at every step in the marketing process.

¹ The National Parks Service. (2024). Myth busters. https://www.nps.gov/subjects/bats/myth-busters.htm.

² Hawkins, S.A. & Hoch, S.J. (1992). Low-Involvement Learning: Memory Without Evaluation. Journal of Consumer Research, 212-225. https://doi.org/10.1086/209297

³ Bacon, F.T. (1979). Credibility of Repeated Statements: Memory for Trivia. Journal of Experimental Psychology: Human Learning and Memory, 5(3), 241-252. https://doi.org/10.1037/0278-7393.5.3.241

⁴ Schwartz, M. (1982). Repetition and Rated Truth Value of Statements. American Journal of Psychology ’95 (Fall), 1043-1056. https://doi.org/10.2307/1422132

⁵ Begg, I., Armour, V., & Kerr, T. (1985). On Believing What We Remember. Canadian Journal of Behavioural Science, 17(3), 199-214. https://doi.org/10.1037/h0080140