The halo effect is a commonly cited reason to pay attention to aesthetics. This refers to people’s tendency to assume that when things are good in one way, they must also be good in other ways (for instance, that attractive people are smarter). Even if you discount the notion that attractive things work better, there is still good reason to make websites and products beautiful, because beautiful presentation in a sense rubs off on everything else connected with it.
We also use visuals to convey other favorable impressions, such as credibility. And this often pays off — after all, in a choice between a clearly amateur website and one that looks professionally designed, more people are going to feel comfortable trusting the better designed site. More trust means greater message acceptance and more sales.
Most of the time.
Researchers have identified certain circumstances where a credible-seeming source can actually harm the persuasive value of messaging. This finding underscores the importance of having strong copy even before considering presentation.
When credibility hurts
Credibility is a tricky variable. To understand this, we need to first distinguish between “credibility” and “persuasion.” Credibility relates to the source of a message. A credible source is one that seems believable. However, persuasion relates to the recipient of a message. A recipient is persuaded if they accept the argument the source is making. So greater persuasion means more people accept the argument after hearing it.
It seems truistic to say that a credible source is more persuasive; yet in reality this is not always the case. In a 2006 study, Zakary Tormala, Pablo Briñol, and Richard Petty found that more credible sources can actually produce lower persuasion in certain unique cases.
Generally, people are more strongly persuaded by individuals they see as more credible. To illustrate, think of a doctor (high credibility) and a high school student (low credibility). We’re generally more likely to trust an argument given to us by the doctor than by the student. But there is one case where this trend is counterintuitively reversed. This case is when the argument the speaker is making is weak.
What does it mean when we say that an argument is weak? Some arguments are just less persuasive than others. Consider the following arguments:
- You should buy Medicine X, even though it is more expensive, because it is 10 times more effective than the generic brand. (Strong argument)
- You should buy Medicine X, even though it is more expensive, because it works a little better for a few people than the generic brand. (Weak argument)
The first argument is clearly more persuasive (i.e., more likely to make people run out and buy Medicine X). The second argument is rather uncompelling.
If people hear a weak argument and then learn that it came from a low-credibility source (the high school student), they won’t show much persuasion (only a small number will buy Medicine X). No surprises there. But what is more surprising is what happens when they learn that the weak argument came from a high-credibility source (the doctor). In this case, persuasion will actually be even lower (no one at all will buy Medicine X). So if the marketing team for Medicine X doesn’t have data on their side, they’ll actually sell more by running advertisements with the student as a spokesman than with the doctor.
In other words, a weak argument is always inferior to a strong one, but it is worse to hear a weak argument from someone who seems credible.
Why it happens
The authors of the study suggest that this effect may be related to people’s confidence. A high-credibility source gives people a greater feeling of confidence about their impressions. So if they read a less-than-stellar endorsement, knowing that the endorsement came from a credible source makes them more confident in their judgment based on that argument — in this case, that the medicine isn’t worth the money.
By contrast, if they read the same lackluster endorsement and learn that it came from a low-credibility source, they become less confident in their judgment. A less credible source increases ambiguity and makes it more difficult to judge the validity of their impressions, which causes attitudes to remain more moderate.
What this means for design
If we extend these findings to the messages in our websites (or apps, or ads, or any other communication vehicle), Tormala et al’s results suggest that credible-looking websites might do more harm than good when the messages aren’t strong. When the primary goal is to persuade (to persuade your customer to buy a product, to persuade Americans to eat more vegetables, etc.), you are better served by first ensuring that persuasive appeals are convincing and logically sound even before investing in making your site look professional and credible. (Of course, ideally you do both.)
In light of the popularity — and usefulness — of rapid exposure tests such as FiveSecondTest (and even 50-ms tests), it can be easy to overemphasize the importance of visual design factors. While these are certainly important, Tormala et al’s study highlights the importance of paying as much attention to content as to aesthetics. A website is first and foremost a tool for communication. Expending all of your resources on creating a credible exterior may actually harm the persuasive impact of your site if the messages it contains are weak.
Tormala, Z. L., Briñol, P., & Petty, R. E. (2006). When credibility attacks: The reverse impact of source credibility on persuasion. Journal of Experimental Psychology, 42, 684-691.