Primary and Secondary Dimensions of Credibility

What makes a source persuasive? 

The quick answer to that question is ​Credibility​. All the research unanimously agrees  that the more credible a source is, the more persuasive that source will be. 

But what exactly is credibility? 

Credibility is a judgment made by a perceiver about the believability of a  communicator ​(O’Keefe, 1990). The interesting part about this definition of credibility  is that if you look at the definition closely, you will notice that credibility is a  receiver-based construct​. What I mean by that is, it is the receiver of the persuasive  message who decides whether the speaker is credible. You can think you're credible  all you want, but if the receiver of your message doesn't believe you are credible, then  the effect of credibility on persuasion will not occur. 

A quick history lesson... Credibility is a fundamental concept to all persuasion theory  and research. The idea dates back to 384 BCE when Aristotle wrote about his concept  of ethos--the character of the source. Similar to logos and pathos, ethos was one of  Aristotle's artistic proofs. He believed that the speaker must fully develop ​his​ character  with ​his​ audience in order to be persuasive. Please note that I fully understand that the  use of "his" in this case is sexist. Unfortunately, in Aristotle's day, it was only the men  who were speaking persuasively in public. 

In the social sciences, the concept of credibility was first studied in the early 1950s in  the work of Hovland, Janis, and Kelly. If you recall from our "history of persuasion"  lecture at the beginning of the semester, Hovland, Janis, and Kelly were the social  psychologists at Yale University who started the variable analytic approach to  persuasion research. Specifically, they attempted to study persuasion by looking at  variables related to the following questions: 

● Who?  ● Says What?  ● To Whom?  ● Through What Channel?   ● To What Effect? 

Notice that the first question Hovland, Janis, and Kelly attempted to answer was  "Who?". They wanted to know what characteristics of the source of the message made  that source more or less persuasive. 

Although the study of credibility from a social scientific perspective started in the  1950s, probably the most well known of all the research studies conducted on the  effect of credibility on persuasion was conducted in 1966 by two social psychologists  by the name of Bochner & Insko. Their study was affectionately referred to as the  "sleep study" because the topic they used in their experiment was "the average  number of hours of sleep an average young adult should get." 

Below is a relatively short lecture on the Bochner and Insko study. As you listen to the  lecture, pay particular attention to why the study is so important to the study of  persuasion.  

https://www.youtube.com/watch?v=7RXYTQTSiwk 

(Links to an external site.) 

 

Who has credibility? 

Below is a chart based on the information you sent me. I only included those  responses that were uploaded by Friday morning, so it is not an exhaustive list of our  class, but we do have enough responses to see some general patterns. What does this  chart tell you about our perceptions with regard to who is credible? Is one sex  perceived as more credible than the other sex? Why do you think that is? Are any jobs  or positions perceived as more credible than others? Do you notice any categories that  are blank, or have very few numbers in them? Why do you think that is? 

 

Now let's look at ​why​ you think these people are credible. Click here (​who do I think is  credible.docx ) for a complete list of people mentioned and a general list of why you  thought your person was credible. 

What does the chart, and our class list of reasons, tell us about credibility? 

What do we know about credibility? 

There are several things we know about credibility from the research and from our own  experiences. The first one we already covered. We know that it's a ​receiver-based  construct​. In order for credibility to have an effect on persuasion, the receiver of the  message has to believe the source is credible. But... you can see from the chart (and  the list) that there are definitely patterns to who we think is credible. For example, we  had slightly more men mentioned than women. Additionally, many of the women  mentioned were family members, friends, or teachers (a traditionally feminine field).  Although there were certainly male family members mentioned too, many of the males  mentioned worked in the public sphere (e.g., experts in their respective fields,  politicians, military leaders, humanitarians, etc.). Our "results" are somewhat consistent  with what the research has found (Carli, 2004). Traditionally, men have been perceived  as more credible than women due to receivers' perceptions of their competence.  Similarly, women have been expected to be more nurturing and warmer than males,  which is probably why we find so many female family members and friends credible  (Carli, 2004).  

A second thing we know about credibility is that it is ​contextual​. What I mean by that  is we might have credibility in one setting or context, but not in another. For example,  in the context of school, and on the topic of persuasion you may find me credible, but  when I go home, no one ever listens to me (i.e., in the family context I have zippo  credibility!). One of your classmates also mentioned the contextual nature of credibility  by explaining that his dad is very credible on many topics, but he is not very  mechanically inclined. Because of that, this individual would not go to his dad for help  with his car! 

A third thing we know about credibility is credibility is ​dynamic​. That means ​who​ we  find credible at one point in time, may not be the same person we find credible at  another point in time. I think a good example of this is journalists. Fifty years ago,  journalists were perceived as very credible. People like Walter Cronkite or Barbara  Walters were sure to have made your list of credible people. In fact, Walter Cronkite  was once known as ​"the most trustworthy man in America."​ But times change,  priorities change, and perceptions of credibility change. In an era of "fake news" and  journalists sometimes sharing opinions rather than facts, very few of my students ever  mention journalists. In fact, up until this semester, my journalist column was always  empty. This semester, however, two journalists made the list! That is likely due to the  fact that during the COVID-19 crisis, we are dependent on them for information. 

Similarly, doctors and scientists have always made my list (Bill Nye is always a  favorite!), but the specific doctors and scientists tend to change over time. For  example, up until this semester, no one ever mentioned ​Dr. Anthony Fauci. This  semester, however, two people mentioned Dr. Fauci. Of course, this is reflective of our  current situation, but it is also a good example of the dynamic nature of credibility. 

In addition to who we find credible changing over time, a single person's credibility can  change from the beginning of a message to the end of that message. Have you ever  listened to someone speak and you thought they were credible, but then they said  something offensive or inaccurate? Just like that, they lost credibility in your eyes!  

Probably the most important thing we know about credibility, however, is that it is a  multi-dimensional construct.​ We know that from the research, and we know that  from the "activity" we did in class. Credibility is not one thing. It's a lot of different  things. Just look at the length of our list! 

Below is a short lecture on the primary and secondary dimensions of credibility. Please  listen to the lecture and compare our class list of "reasons" to it. Did our list include all  of the primary and secondary dimensions of credibility? I think it did...  

https://www.youtube.com/watch?v=DSlyQGRkaBI 

(Links to an external site.) 

 

Now that you know what the primary and secondary dimensions of credibility are, I'd  like you to apply your knowledge to a speech that was given by President Barack  Obama at the University of Maryland College Park in 2009. In this speech, he was  trying to garner support for his health care reform plan. Please listen to his speech and  then complete your ​Discussion Question​ on it (​Primary and Secondary Dimensions of  Credibility). 

https://www.youtube.com/watch?v=Y3XkOK57Fn4 

(Links to an external site.) 

 

The Sleeper Effect 

I just spent the majority of this lecture emphasizing the point that credibility enhances  persuasion. Highly credible sources are more persuasive than low or moderately  credible sources. The effect of credibility on persuasion diminishes over time, however.  That is because ​credibility is a peripheral cue to persuasion​. When the cue is  present (i.e., the credible source is standing in front of us), it affects persuasion, but  when the credible source is no longer there, the credibility of the source ceases to  influence us. What that means is that in general, credibility has a direct linear effect on  persuasion, but this effect is fleeting (i.e., it goes away over time). 

There is a case, however, when a low credibility source can actually be more  persuasive over time. This case is called the ​Sleeper Effect​. Simply stated, the ​Sleeper  Effect​ is a phenomenon in which a message from a low credibility source actually gains  in persuasiveness over time. This is because low credibility initially acts as a  "discounting cue"​. Because the source of the message is not credible, we initially  "discount" the message. We don't listen to it fully or we don't believe it. BUT... If that  low credibility source has good arguments, then as time wears on, we may forget who  said the message, but we remember what the message said. If the arguments in the  message are strong, and we think about them at a later date, we can actually be  persuaded by a low credibility source long after the message was delivered. 

What is the lesson to be learned by the Sleeper Effect? The lesson is, yes, it's  important to establish your credibility with your audience, but it is equally, if not more,  important to have good, strong arguments. When all else fails, have strong arguments! 

Enhancing Credibility 

In conclusion, credibility is a very strong predictor of persuasion. Credibility is a  receiver-based construct, however, so it must be established with your audience. If  you don't have any special training or knowledge to make you credible to speak, there  are still things you can do to enhance your level of credibility with your audience. Some  of these things include: 

● Be prepared to speak  ● Provide evidence for your arguments  ● Tell your audience why you are qualified to speak  ● Build trust  ● Display goodwill  ● Be likable and sociable  ● Be a dynamic communicator in both language and delivery  ● Establish similarity with your audience (Why? Because the research shows 

that we like people who are similar to us)  ● Get the audience involved in what you are talking about  ●