All of us want to be more effective communicators.

One key to effectiveness is credibility, or believability.

I'm going to tell you about credibility - what it is, how you increase your own credibility, and what effect that has on your persuasive success.

The Perception of Credibility

One of the most important communication skills is persuasive effectiveness. Our ability to persuade people, to change their attitudes, to change their intentions, to change their behaviors. To sell them things, to convince them of things. Persuasion is a critically important communication skill. And one of the key factors in persuasive effectiveness is credibility.

Now all of us had heard the word credibility, and all of us have a general sense that it's better to be credible than not to be credible. Or, it's better to have high credibility than to have low credibility. But what exactly is credibility? Well, we can have a sort of intuitive sense, like believability. To what extent do I believe this person? Can I trust them? Do I believe they know what they're talking about?

When I talk about credibility, I'm talking about perceived credibility. That is, the extent to which the audience perceives that the speaker or the communicator is credible. Credibility isn't really in the speaker necessarily, although there are characteristics that are associated with credibility. When researchers study credibility, they study the audience's perception of the speaker's credibility. In this post, for convenience I'm just going to use ‘credibility,’ but I always mean perceived credibility - credibility in the eyes of the audience.

Two Dimensions of Credibility

There's been a lot of research on credibility and that research has revealed that there are two underlying factors that are at work when people perceive a speaker as credible. In an obvious and intuitive way, they are expertise and trustworthiness.

1. Expertise

Expertise refers to the extent to which the audience perceives the speaker to be skilled, intelligent, knowledgeable, expert, and so on. Expertise is about the extent to which the audience believes the speaker knows what's true. That is, they have the knowledge, the skill, the expertise to know what's true.

2. Trustworthiness

The second dimension of credibility is called trustworthiness. Again, I think this is pretty intuitively obvious as well. Trustworthiness is about the extent to which the audience perceives the speaker to be honest, just, fair, and open-minded. These are the sort of sub dimensions of trustworthiness. Whereas expertise is about whether or not the speaker knows what is true, trustworthiness is about whether or not the speaker will tell the truth regardless of whether they know what's true or not.

These are the two main dimensions of credibility. If you want to be seen as credible, you have to enhance your expertise and your trustworthiness; the extent to which people perceive you as an expert and as someone who's honest, and fair, and trustworthy. So those are the two main dimensions of credibility.

5 Credibility Factors

What makes people seem more or less credible? Anything that influences these judgments of expertise or trustworthiness should make the communicator appear to be more credible. Research has identified five different factors that influence perceptions of credibility.

1. Credentials

The first is pretty obvious: credentials. This is the extent to which someone, by their education or occupation or position, has a status which reflects credibility. I'll often say, I am a PhD. I'm a college professor at Northwestern University. These things are intended to enhance my credibility.

Education, occupation, and experience will enhance your credibility, to the extent that the audience knows about them. If the audience doesn't know about them, if I don't introduce myself as having a PhD or being a college professor, then all of my expertise and experience and occupation won't enhance my credibility because the audience won't know about it.

2. Non-Fluency in Speech

The second factor which detracts from your credibility is non-fluency or dis-fluency in speech. So if you use the wrong words, if you stumble over your words, or mispronounce words, or have long pauses, or say a lot of “ah, um, uh,” then these dis-fluencies will make people perceive you as less credible. You will be perceived as either less expert or less trustworthy. I have a previous post where I talk about how you can reduce your “ums” and “ahs.”

3. Citing Credible Sources

The third factor that increases credibility is the extent to which you cite reliable evidence or reliable sources. So if you cite a study that was published in the New England Journal of Medicine or in the Journal of Science, or a high credibility newspaper or news source, then the credibility of that news source rubs off on you, and you yourself appear credible. It's better to cite a specific study than to say just something like “Studies show” or “Everybody knows.” Citing specific credible sources enhances your credibility because it makes people think that you know what you're talking about.

4. Position of Advocation

The fourth factor that influences perceptions of credibility is a really interesting one. It has to do with the position that the communicator is advocating. What this means is that if I advocate a position which appears to be against my own interest, then I will seem more credible. An example might be something like a Democratic politician praising or advocating for a Republican politician, or a prosecutor advocating for lower sentencing guidelines. Because these positions would appear to be against their own interests, it seems the only reason they would advocate for them is because they must really be true. They must really be telling the truth, or they must really know what they're talking about to advocate for a position which is against their own interest. So whenever you advocate for something that's against your perceived interests, then people will perceive you as being more credible.

Related to this, say you're trying to sell something. If you talk about all the attributes of your product versus the attributes of a product that your competitor makes, and you acknowledge that your product is not superior on every single dimension but maybe is equal on some dimensions and only superior on a few, you'll be perceived as more credible than someone who says their product is superior to the competitors on every dimension.

5. Liking

The final factor is liking. To the extent that the audience likes the communicator, they will perceive them not as more expert, but as more trustworthy. So liking and trustworthiness tend to be very similar dimensions, and if an audience likes the speaker, they will also tend to trust the speaker. It doesn't make the audience think that the speaker is knowledgeable or expert, but it does make them think that they are likely to be telling the truth.

So I guess that means make yourself likable, if you can. Maybe use a little bit of humor, but not too much. This will enhance perceptions of likability, and maybe then enhance perceptions of trustworthiness, and therefore your credibility.

The Paradox of Credibility

I've defined credibility. Now we should ask ourselves, well, what effect does credibility have on communication outcomes?

Is it always better to be a high credibility speaker? I think intuitively, before I looked at the research, I thought, yes, I always want to enhance my credibility. Credibility is good. High credibility is good, low credibility is bad. I want to be seen as a credible speaker, and certainly as someone who's like an illegitimate expert because I have a PhD and so on. I believe in credibility, and I think it enhances my effectiveness.

But the research is actually more complicated than that. Having high credibility is not always the most effective position to be in. The first thing to understand is that sometimes credibility doesn't matter very much. Credibility tends to matter most when the audience doesn't care very much about the issue that you're talking about.

This seems a little bit counter-intuitive. You would think, well, the more the audience cares about the issue, the more they should care whether I'm an expert or whether I'm trustworthy. But the opposite is true. When people care a lot about an issue, they do a lot of their own thinking about it. They process your message very deeply. Credibility is a somewhat superficial characteristic of the speaker of the source of the message. But when people care very much about an issue, they analyze the message itself.

Source factors, like credibility or attractiveness, are less important than the strength of the arguments, for example. To the extent that people really care about an issue, they will tend to examine the message quality and the strength of the arguments more than they'll pay attention to superficial source factors like credibility.

So credibility is (counter-intuitively) most important when people don't care very much about the issue. If people are just superficially engaged in an issue, then they'll mostly just rely on superficial source cues, like credibility, to decide what to do, or what position to believe, or what attitude to have, or what behavior to engage in. "I don't really care very much if that person is an expert, I'll just do what they say." Whereas when they really care about an issue, they'll ignore the surface characteristics and look more at the arguments.

Another factor that matters very much, and this is pretty obvious, is when the speaker's credibility is revealed to the audience. Sometimes when you read an article or see certain kinds of advertisement, you're not sure who the source is until the end of the message. Credibility doesn't have any effect unless the audience knows about your credibility.

The only time credibility is going to have an effect is when the audience knows about your expertise or your trustworthiness before being exposed to your message. If they only find out at the end, they're not going to know very much about your credibility and it won't impact how they process the message. So it's kind of obvious, but if you want your credibility to have an impact on your effectiveness, then you have to let people know about your credibility before you talk to them.

To return to this fundamental issue, is it always better to have high credibility or is it sometimes better to have low credibility? It turns out it's actually sometimes better to have low credibility. High credibility is more important when the audience disagrees with the speaker's message. Under those circumstances, the high-credibility communicator's expertise and trustworthiness have an opportunity to change the minds of people who oppose the position that they're advocating. When you're communicating a message that the audience already agrees with, one that is consistent with the audience's attitudes, then low credibility speakers actually have the advantage.

This seems really strange, but Dan O'Keefe, the persuasion researcher whose textbook I used to develop most of the material for this lecture, explains it this way. When a low credibility speaker is talking about a topic and advocating for an issue that you already support, even if they're not doing a very good job advocating it, you're going to fill in. You're going to sort of in your mind, help them make the arguments. Fill in more facts, fill in more data, fill in more better arguments, and make up for the fact that they're a low credibility speaker. In fact, compensate for them. Because the issue that they're advocating is one that you also advocate, and you don't want the low credibility person to look bad, you mentally help them out with the argument. That paradoxically is why low credibility speakers are more effective when they're advocating a position that the audience already had.

Summary

So there you have it! That's what credibility is. I've talked about ways you can enhance your own credibility, and I've talked about the circumstances under which credibility is important.

Credibility is really only important when the issue is relatively of low importance to the audience, so they process superficial source views like credibility. When it's high importance, they're going to process the substance of the argument and not so much the characteristics of the speaker. You have to, of course, tell people about your credibility in advance of communicating with them if you want credibility to make any difference.