#100: A Unified Model of Persuasion

No, I didn't get a new podcast theme song. This is the opening to a film made in the 1940s as World War II was underway. It's part of a series of propaganda films called Why We Fight, produced by the United States Department of War. Eventually they were screened for the public, but they were originally made for US soldiers to help them understand why their country was involved in the war. They were actually directed by Frank Capra, the same guy who would go on to direct its wonderful life a few years later. Animators at Disney made animated charts and maps, Hollywood composers wrote the music. These were well-made films. The first film in the series won an Academy Award in 1942, and in 2000 the US Library of Congress elected to preserve these culturally significant films in the National Film Registry. But I'm not telling you about these films because of their place in military history or cinema history. I'm telling you about them because they're also essential to the history of a science of persuasion. As the United States was entering the war, the Army's information and education division set up a so-called "research branch" with the mission to gather data about soldiers' opinions. In particular, they wanted to see whether the programs they were developing to boost soldier morale were actually doing anything, and to their credit, they turned to science. One of the people who ended up being instrumental was Carl Houghland, a psychology professor at Yale University who was primarily interested in how people learn. Houghland worked for the government from 1942 to 1945, applying his research skills to testing the effectiveness of propaganda films, particularly the fourth film in the Why We Fight series. In 1949, he, along with two other researchers Arthur Loomsdane and Fred Sheffield, published the book "Experiments on Mass Communication." In the book, they reported the results of their experiments, showing that propaganda films were effective in some ways, but not others. But beyond what they found, the fact that they applied their social science toolkits to the question of propaganda at all marked a real turning point in how we understand how persuasion works. It launched a new avenue of research for Houghland that continued the tradition of using meticulous scientific methods to test when a message is ultimately influential. It emphasized how persuasion depends on the kind of message being used, the audience receiving the message, and the person delivering the message. All our points we still value today. Eventually, psychology research was lousy with results about persuasion, piling up from a mountain of studies. The problem was the results didn't always add up. It was a period of crisis, as people didn't know what to make of this science of persuasion. When the results of one study didn't seem consistent with the results of another. Was there there or whatever the saying is? If social scientists were going to carry on trying to understand what makes people change their minds when they get information, they were going to have to make sense of the mess. Fortunately, 40 years or so after Houghland's crew started down this road, we started to get some clearer answers. You're listening to Opinion Science, the show about our opinions, where they come from, and how we talk about them. I'm Andy LaTrell. And welcome back. I took a longer break from producing the show than I planned on. But after putting out this show for the last four years, apparently I needed to step away for just a little bit. But we're back. Episode 100. I mean, technically more than 100 episodes have been published on this feed, but for those of you worried about the Opinion Science canon, this is officially the 100th episode. And it's an episode that I've wanted to put out for a long time. I started grad school in 2010 at Ohio State University, and my PhD advisor was Dr. Richard Petty. I'm going to call him Rich throughout this episode. He's like a famous guy in the right crowd, because he helped develop a theoretical model of persuasion that has stood the test of time. It's the elaboration likelihood model. And it organized a bunch of principles of persuasion into something that helps account for how and when a message will be persuasive. That's the idea I want to feature this week. But first, let's get on the same wavelength. When I say persuasion, I'm generally talking about what happens when a message affects a person's attitude or opinion. Messages come in all shapes and sizes. Ads on TV, campaigns, speeches, newspaper articles, visits from a salesperson. They're all messages that are trying to change your mind about something. And the things these messages are trying to change, our attitudes, are just how much we think of something positively or negatively. So it's election season here in the United States, and I live in a contested state. So all I see these days are political advertisements, messages that are trying to make me like one candidate more and oppose another. In other words, they're trying to change my attitudes toward the candidates. So how do these messages work? That's what Rich Petty wanted to know. In high school, I was on the debate team. You really have to marshal all of your arguments together and so on and so forth. So his experience with debate set him up to be curious about the psychology of persuasion. Well, and so I didn't lead directly to the other, but it does suggest that that's a topic I was interested in. Okay, fine. But the point is that by the time he got to grad school at Ohio State in the 1970s, he had been thinking about the sorts of arguments that win debates. And it turns out there was this whole field of psychology devoted to understanding how persuasion works. Going back to Havlund's experiments during the war, the evidence had been piling up, which is maybe why it was surprising when Rich talked to one of the Ohio State professors about studying persuasion and I said avoid the topic at all costs. The heyday for research on this topic was over as far as they were concerned. It was in the 1960s that research on people's attitudes and how they change was all the rage. And it was so popular, I think, within social psychology that everybody was doing it. And that's it sort of collapsed upon itself. Because people had been churning out these studies on persuasion, but the results were not always consistent with each other. The classic case of this has to do with how much people are swayed by experts. In general, you might think that it's more persuasive when a noted expert makes an argument. And sure enough, that's something that Havlund found in his early studies. But then other studies would come out showing that expertise actually hurts persuasion or that expertise doesn't matter. It was confusing. I mean, the psychologist, Mustafa Sharif literally called it a quote "raining confusion" end quote. In the persuasion section of a 1978 psychology textbook, the author even wrote that quote, "the most disturbing aspect of these results is their inconsistency." End quote. There were papers at the time that said, "Okay, I think we're done." Until a new paradigm comes along or until this is just not very useful. But a new paradigm was about to come along. And the seeds of it had already been sewn at Ohio State before Rich got there. They would lay the foundation for their model of persuasion. So in 1968, three social psychology professors at Ohio State, Tony Greenwald, Tim Brock, and Tom Oström published a book called "Psychological Foundations of Attitudes." They'd collected up a bunch of new ideas in the science of opinions and how they change, and one of the most influential ideas presented in that book was an approach to understanding persuasion called "The Cognitive Responses Approach." Psychologists love to give fancy names to simple ideas. In this case, cognitive responses just refers to the thoughts that people have while they're digesting a message, like while you've been listening to this podcast, you might have had thoughts like, "What an interesting idea!" or, "What an annoying voice, Andy has!" Or, "I'm hungry." Those are your cognitive responses. And the breakthrough was that messages alone don't change minds. You don't just magically get a new opinion after listening to the news. Instead, the power of a message is that it can spark thoughts in your own head. It's those thoughts that can reshape your opinions. Sometimes, a message gets you thinking in a way that supports its key point. Like, if an ad for Dunkin' Donuts makes you think, "Yeah, pumpkin flavored iced coffee would be delicious," then the message got you thinking in a persuasive way. But it's also possible for you to see the ad, understand all of its key points, but have a thought like, "This is just part of some nonsense pumpkin spice trend that's gone too far." Same message, but it was your thought in response that got you to resist persuasion. This was a big idea at the time, and they came up with new ways to study persuasion that showcased the importance of people's thoughts or cognitive responses. And even though it was this bold movement in persuasion psychology that attracted Rich Petty to Ohio State as a potential grad student, by the time he actually got there, the professors felt like it was all settled science. Nobody was really doing research on this anymore, but Rich caught two lucky breaks. The first was that he was able to find a professor who was interested in persuasion. As a newly admitted student, he had to find an advisor. So I want to all the different faculty, none of whom mentioned attitudes as what they were interested in or doing. And then there was this one new guy. who was a visiting faculty member, Bob Childini. And he was doing attitudes and social influence. And so it was like, well, literally I thought, did I come to the right graduate program now, given nobody's doing this? But thank goodness Childini was there. - Okay, if you're not familiar with Bob Childini, you can check out episode 37 of this podcast called Opinion Science. I think it's called. He's published a handful of extremely popular books on persuasion and influence that are based in psychological research and communicated in a way that gives people practical strategies to influence others. It's earned him the nickname, the Godfather of influence. But in the mid 70s, none of that had happened yet. He was just a plucky new professor who happened to be visiting Ohio State for a year. And so he enriched it some research together on attitude change, which would chart the course for a long career chasing similar questions. But after that year, Childini headed back to his post at Arizona State, and the two of them would continue collaborating by phone and even by mail. - Literally, you'd have to mail manuscripts back and forth if you're working on it together. So it was really kind of amazing. But yeah, thank goodness for Bob Childini. - And it wasn't just Rich who was lucky to find Bob. The feeling was mutual. Here's Bob Childini. - I remember after a couple of weeks writing back to my colleagues here in Arizona saying, "My God, they have good graduates through this year. My God, I was astounded." - So the first bout of luck was connecting with Childini that first year. But the other lucky break was one that would have a more stable influence. The same year, Rich started grad school. So did a guy named John Kessiopo. I obviously would have loved to talk to John for this episode, but he unfortunately passed away in 2018. Although he left us too soon, he used every ounce of the life he had, becoming a force in social psychology in his own right, founding a movement called social neuroscience that looked at the biological drivers of social behavior and helping pioneer the scientific study of loneliness. But in 1973, he and Rich Petty were new graduate students in Ohio. Rich was living on campus and John was living with his girlfriend, but it didn't take long before Rich was fed up with the dorms and John had broken up with his girlfriend and like some 70s sitcom, they moved into a house together in the middle of winter. So John and I kind of roamed in together and then you get to know somebody very well. We're taking all the same classes together and just had lots of time to interact. I became really good friends. That house, by the way, was a very run down, part of the most run down place that I'd ever lived in in my life. And so when we went home for Christmas break, there was a break in and everything we owned of any value was stolen. And then we got our heating bill for the winter and it was five times our monthly salary because the house had no insulation. Everything leaked like a sieve. It was a particularly cold winter. And we just had the heat cranked up. And then we got our heating bill, which took us another year and a half to pay off once we moved. So anyway, so we ended up moving at the end of the year to something that couldn't be more different than that old house. And it was to this brand new apartment complex. With one very important feature, the heating was in the rent. But that first drafty run down house actually turns out to be a really important location in the story because it was in that house that Rich and John were trying to study for the class on attitudes and persuasion. But remember, the state of the science then was a mess. It felt like there were a million findings that didn't have anything to do with each other. And their textbook wasn't helping them. Each chapter was just a list of studies. Just some rays of all these studies that the test was going to be, can you memorize all these studies? Which is rather difficult because they all would find different things. So they needed a way to make sense of all the confusion. Was there any order to the chaos? And if you're starting to picture a wide-eyed conspiracy theorist connecting pictures on the wall with strings, I feel like you're not far off. I'm sure the painting the wall with the chalkboard paint was not my idea. I'm sure that was John's idea. Because he just loved to doodle and write and work out things. And he was very mathematically oriented. And so of course in Matthew, we were writing out equations and things. You heard that right. They painted the wall in their dingy campus house to turn it into a giant chalkboard. They needed a way to map out all of these studies in this clunky textbook to see if they could figure out any themes that would help them remember which studies found what. You can imagine making a big matrix on the board with the different variables down one column and other characteristics of studies. Bob Chaldeanie again. I remember visiting them. And this entire wall was covered with chalk, what they had found, what they were predicting, and what they were going to do next, and so on. Not only did they do social psychology at the office, they lived it. They breathed it. So after all that, how did Richard John do on their test? Probably fine. But that's really not the point. Because it turned out that this attempt to make sense of things just so they could do OK on a test, unlocked something. All of these conversations at the chalkboard in their house got them thinking that maybe there really was some order to be found. Maybe the themes they came up with as memorization tricks captured real differences in how messages can change minds. This all came to a head when Rich was finishing up his PhD dissertation. Once Chaldeanie had gone back to Arizona, Rich needed a new advisor, an actual Ohio State professor. The psychologist Tim Brock became his mentor. Tim read the first draft of the dissertation. And also the studies are all well and good. But where's your theory? For dissertation, you need to go off and develop a theory of attitude change. That's what I'd like to see in your dissertation, which is quite a challenge when you think your dissertation's done and your challenge to write a theory. It was a chance to integrate all of these thoughts that had developed from the Chaldeanie study working with John, studying for the test, to put it all in a handy form at the end of the dissertation. And Tim goes, great, you got a theory, so forth. In my mind, it was like, well, this is kind of a nice roadmap of becoming an assistant professor starting the next year that now we can start to test those things. And John Cassiopo was also about to start as an assistant professor at another university. But they would have these weekly phone calls to talk about what research was next on the docket, which was just a continuation of what we had done in grad school. So we were able to continue that, which was so critical, as a beginning assistant professor. So the two of them did a bunch of studies, thought long and hard about different pieces of the puzzle. And in 1986, they published their full elaboration likelihood model, which took their early attempts to make sense of the psychology of persuasion. I'd love to know what we actually had on the board. And provide a complete integrated theory for all the different sorts of variables that matter and when they result in successful persuasion. That grand theory here in a moment. [MUSIC PLAYING] OK, so Rich Petty and John Cassiopo had spent years trying to see if persuasion could be understood systematically. From just trying to pass a test to sketching out a real theory, they did eventually get there. And their breakthrough comes down to one really important insight. Human beings are limited. Our brains can only think carefully about so much stuff before they're spent. So we're picky about what we pay attention to. Imagine your phone battery is at 5%, and you don't have a charger with you. You're going to get really choosy about what you use your phone for, same with your noggin. There's an enormous number of things in the world that you could pay attention to. Think of all the messages you could see or hear throughout the day. You couldn't possibly carefully consider all of them. Instead, we only tend to give something our undivided attention when our mind battery is fully charged. And it's something we actually want to understand. In Rich and John's model, carefully thinking about and reflecting on a message is called elaborating on the message. And the key idea is that the ways in which a person will be persuaded by a message depends on how likely the person is to be elaborating on it. Hey, wait, that's the name of the model, the elaboration likelihood model. And it's worth noting that this is a continuum. You could be thinking super hard about a message. You could be completely oblivious to it, but you could also be thinking about it a little bit or a lot. This partly depends on your ability to think, kind of like how charged up your mind battery is. If you're just too tired or distracted to process a complicated argument, you just aren't going to. But you could be perfectly capable of thinking about a message and have no desire to do so. So you also have to want to think. Like the message has to be about something that matters to you or surprises you or affects you. The seed of this idea, by the way, goes all the way back to Rich's first study with Bob Chaldeini. By the time Chaldeini got to Ohio State, he had already done some research on what people do when they're about to talk about their opinion with someone who disagrees with them. He had found that people will show. shift their own opinion to be more neutral in these situations, presumably because they think it'll make the other person like them more. But do people really back away from all of their opinions that easily? One thing Rich noticed when he was looking at Chaldeen's study was that. The topic he was using was really unimportant to people and I'm like, "Nobody cares about whatever this is." And so we varied something that was going to be very important later in my career and that's how important the topic was to you. And they found that sure, if the topic is not important to the person, that person will become more neutral if they're about to talk to another person with the opposite view. But that doesn't happen if the topic is important. In fact, people even became somewhat more entrenched in their own view if the topic was important. So, it was clear that the topic matters. It changed the rules of the game. And it was that basic idea that evolved into the elaboration-likelihood model. Because when the topic is important to you, you're invested in what messages on that topic have to say. You become more likely to elaborate. And the reason this matters is that according to the elaboration-likelihood model, persuasion works differently depending on how much people are thinking about a message. To simplify it a little bit what this often means is that different sorts of things are persuasive, depending on how much people are willing and able to think. Let's start with how persuasion can work when people cannot think very much or they just don't want to. In these situations, messages can still change people's opinions, but they've got to get through to people in a really simple way. One way this can work is to create a simple, positive or negative feeling that the person can quickly attach to the topic, like think of a product endorsed by a likable celebrity. You may not have the wherewithal to think about every feature of the product, but you can have a quick, positive reaction to the celebrity and associate that feeling with the product. Or you go to a baseball game and there's a giant Coca-Cola logo on the scoreboard and you can associate your love of the baseball team with the brand on display. Easy. Another major way in which messages can be persuasive when people are not thinking that much is through heuristics. These are simple mental shortcuts you can take when thinking about something, so rather than carefully rationally thinking through every twist and turn in a problem, you can make a good enough judgment by applying some simple rules. In the case of persuasion, you could sit down and scrutinize every claim made in a message. Or you could make it easier on yourself and apply a simple rule. If the person who said it is an expert, then it's probably true. That's so much easier. So the credibility of the communicator can enhance persuasion when the audience isn't paying much attention because they can at least use this easy heuristic to figure out what to make of the message. And there are all sorts of things that show up in messages that people can apply heuristics to. Like there's a new feature on Amazon that I noticed recently. It's a little label that just says, "Most people who buy this, keep it." Or this item is often returned. So sure, I could read every review and all of the product information and make a fully informed decision. Or I could see that a lot of people return the product and think, "Good enough, I won't buy it." Other kinds of heuristics are things like, "If the message includes a lot of arguments, it's probably right. If the communicator is speaking confidently, they're probably right. If the message comes from a group I belong to, then it's worth accepting and on and on and on." In the elaboration likelihood model, all of these variables are called peripheral cues. There are these incidental aspects of the persuasion situation that can set off mental processes that don't take much effort and can result in persuasion. Sometimes scholars will say that if someone is not likely to be thinking very much, if they're going to be persuaded, it'll be by the peripheral route to persuasion. Okay, but what about when people do want to think about a message and they're able to do so? Well, this is where we come back to that idea of cognitive responses again. The idea that people are persuaded not by the message itself, but by the thoughts that occur to them as they work through the message. You can't have thoughts without thinking, so that cognitive responses stuff only explains persuasion in situations when people are likely to elaborate or think. But the important thing here is that people's thoughts are not just random. They're guided by the message and other aspects of the persuasion situation. One of the most fundamental principle here is that people's thoughts are guided by the strength of the arguments in the message. When a message makes a lot of really solid, well-articulated points that are logically sound, it'll generally get people thinking in ways that support the message's conclusion. So the argument that health scientists have found that eating more blueberries leads to a 40% reduction in disease doesn't magically make me like blueberries more, but it does make me think, "Wow, 40% is a huge decrease. This could make a big difference." And it's that thought that persuades me. On the other hand, when a message is really weak and has no legitimate arguments, it instead gets people thinking in ways that oppose the message's conclusion. So let's say the argument is actually that health scientists have found that eating more blueberries leads to a 0.001% reduction in disease. When I hear that, I start to think. But that's nothing. Why should I buy more blueberries if they're basically worthless? Those are negative thoughts. Sometimes we call them counterarguments. And the more of those we have, the less persuaded we are. The point of this is to say that the content of a message, the quality of its arguments, matters because of the thoughts that they evoke. But if we're not capable of paying close attention to the message or we don't want to, we're not going to have those thoughts at all. And so the quality of the message itself won't matter much. Instead, it's when we are motivated and able to think about what a message has to say that persuasion depends critically on the quality of the message's arguments. In contrast to the peripheral route, this is sometimes called the central route to persuasion, because it emphasizes the merits of the arguments that are central to the issue. Okay. All right. I've been doing a lot of explaining in abstract terms. Let's pause for a second and look at an experiment that put all of these basic ideas to the test. It's one of the original experiments that Rich Petty and John Cassiopo did together, and it lays everything out in such a clear and simple way. They ask a bunch of college students to listen to a recorded message about a new policy that their school was considering. The policy would require all college seniors to take a comprehensive exam covering everything they had learned in their major before they could graduate. This is not an idea that students love, so if they could be convinced to support this policy, it would be a real persuasion win. So the way researchers scientifically test what features of a message affect persuasion is they randomly tweak those features from one person to the next and see if those tweaks affect people's opinions. In this case, we're actually looking at the combined effects of these tweaks. The first key thing that differed between people in the study was the actual message they heard. The research team came up with two different messages, one with strong arguments and one with weak arguments. The strong arguments relied on data and statistics proving that this policy would result in higher standardized test scores and career opportunities, but the weak arguments were full of unconvincing or even undesirable anecdotal evidence. Like a guy who said his brother had to take a comprehensive exam in college, and now he manages a large restaurant. Like, okay. But regardless of which message they would hear, before they heard it, everyone learned something about where the message came from. Sometimes they thought it came from a very credible source, education experts at the Carnegie Commission on Higher Education, but sometimes they thought it came from a much less credible source, kids at a local high school. And there was one more critical tweak. Regardless of what the message said or where it came from, some people thought that the whole exercise was largely hypothetical. Even if the exam policy was adopted at their school, they heard that it wouldn't go into effect for another 10 years, so it had no personal ramifications. But other students were told that the policy that they would hear about was being actively considered and would go into effect next year at their school. All of a sudden this issue got super important because it's relevant to their personal experience. And in theory, that should make them very motivated to elaborate. In other words, they're going to really want to pay close attention to this message so they understand it fully. And with that, all of our elaboration-likelihood game pieces are set. In the end, what we're really interested in is how much to these students end up saying that they support the policy. What is it in the message that will be most influential for their own opinion? Let's start with the students who were told the policy wouldn't go into effect for another 10 years. Presumably, they don't feel the fire to spend their energy deeply considering this message that doesn't mean anything to them anyway. And when you look at their opinions of the exam policy, the quality of the message just didn't seem to matter. Using our arguments, weak arguments, they didn't move the needle. The source of the message was all that mattered to them. These students supported the policy more if it was a bunch of experts who said it was a good idea. But not if it was high school kids. This is the peripheral route in action, when the students were not very likely to be thinking much. Persuasion depended on the heuristics they could apply, to this simple information about where the message came from. But what about the students with skin in the game? The students who would be personally affected and so would really want to pay attention? Well, welcome to the central route, because these students didn't much care where the message came from, education experts, high school kids, find whatever, what really mattered was the quality of the arguments. For them, if the arguments were solid, they supported the policy more. Not so much if the arguments turned out to be nonsense. So peripheral cues, like the source's expertise, mattered when people were not likely to think very much. And the quality of the arguments mattered when people were likely to think. That's the heart of the elaboration-likelihood model. And it's a pattern of results that comes up over and over again. But wait, there's more. I want to briefly mention one other kind of persuasion that can happen when people are thinking about the message, because what happens if the message is not totally strong or totally weak? When you have to read between the lines to figure out how much you should actually agree with this message, well, when things get murky and ambiguous, we become prone to bias. Ultimately, this means that some aspect of the persuasion situation can adjust to think mostly positive thoughts or mostly negative thoughts when we get a message. Like, imagine you hear someone on a podcast going on and on about the health benefits of taking super cold showers or whatever comes up on all of these wellness podcasts. Maybe some of their arguments seem pretty solid, and other arguments seem kind of dubious. Are you persuaded or not? Well, it could depend on who is making the claims. If it's a credentialed expert, you might end up thinking more about the strong arguments and less about the weak arguments. But if it's some huckster with no claimed expertise, you might instead focus on refuting their weak arguments and spend less time thinking about their strong ones. This is still thoughtful, central route persuasion, but it's worth appreciating that just because it's thoughtful doesn't mean it's objective. Okay, that was a lot. But hopefully you're starting to see that persuasion is more complicated than what Carl Houghland and his crew may have bargained for in the 1940s. Lots of things can make a message more or less persuasive, but they're going to do so differently for different people in situations, for different reasons. It makes finding a holy grail of persuasion strategy a bit of a fool's errands. Everyone wants to know, well, what's the best cue to use? Is there, what, I just want to know the best one, or what's the best argument, or what's the best thing? It's like, no, if it were that simple, you know, we wouldn't have 10,000 studies on influence. That's not that simple. [Music] There's one more wrinkle to the story of the elaboration-likelihood model, though. For years, the ideas that Rich Petty and John Casio Bo proposed were supported again and again by researchers putting it to the test. So we know that persuasion can depend on heuristics, arguments, and biased thinking, but it turned out that there's something else that can affect the persuasion process when people are motivated and able to think carefully about a message. And to understand what it is, we start with another stroke of luck. I wanted to be a psychologist because I thought that was going to give us some strength, some mental powers, if you will. That's Pablo Brinol. He's a psychology professor at the University of D'Authonema, Day Madrid, in Spain. But back in the 1990s, he was only starting to think he might like to study psychology. I thought time I was also considering going to the army. So on the one hand, he's like, "Well, I'll train my body in the army, and I'll train my mind by becoming a psychologist." And what really inspired him to go into social psychology in particular? Bob Chaldeany. Thank goodness for a Bob Chaldeany. Bob Chaldeany. The guy who popularized the science of persuasion and influence, and the guy who was there for Rich Petty when he started grad school. I'm very grateful to him. I told him many times then in person. So Pablo is a graduate student in Madrid studying psychology, conducting some experiments, and thinking a lot about the science of persuasion. In the course of his studies, he had obviously come across Rich Petty's name, and wouldn't you know it? Rich was coming to Spain. I got a flyer in my department advertising this event. Rich was coming to present at a conference on political persuasion and propaganda, but there was one hitch. The conference he was speaking at was in Salamanca, not Madrid, but Pablo was determined. Even though I was living in a different city in Madrid, just like about two to three hours drive. Also, that conference took place during my birthday. The registration fee was a present, a gift for my birthday. From my former advisor in Madrid, Alberto Beterra. He said, "You know what you're going to get for your birthday this year? This meeting that you want to go, I'm willing to pay for it." Well, great, so I have my friend that comes with me and I have my advisor that is paying for the fee. And I was the one that wanted to go in the first place and now all the ingredients were in the right place for that to happen. Okay, so Pablo makes the trek to Salamanca where he's about to see you talk by V. Rich Petty. I mean, obviously he was the biggest expert in attitude change in persuasion from the point of view of science. He gets to the meeting, which is in this historical building in Salamanca, one of the oldest college towns in Europe. So the setup was beautiful. You know, it felt more like a cathedral than a convention accomplished. And the audience was mostly undergraduate students in Salamanca, folks whose primary language was Spanish, not English, as you might guess. Rich speaks English, not Spanish. And this is all fine because people in the audience can listen on headphones during the talk in here alive translators simultaneously providing the Spanish translation. But then it's time for the question and answer. That's Rich Petty again. And the first person raises their hand and I look over at them and they say something in Spanish very quickly. I learned Spanish in high school, but not all enough to understand them. And then I look up to the booth where the translator was going to translate back to me and the translator has gone. Translator has deported. No translator for the question and answer. Nobody thought about translating things back to him. Oh my, this is really awkward. What do I do? I felt like I was probably the closest person he could use for that role. And then some young gentleman who's sitting in the audience raises his hand and he says, well, the question is something like that and tells me the question is like, oh, thank God. And then I give my answer and then this person translates back to the other person. So that was a little bit of a naxi then we got lucky. So this is great. We do my question and answer that way. And so of course, right after that, I have to go over to the person and go, thank you so much for doing this. And it turns out this person was Pablo who was a graduate student doing a dissertation on persuasion. So then we started talking and we sort of said, well, let's stay in touch as I go back to the US. And so that was the first introduction. That was actually instrumental in having more quality time with them after the presentations. So in this happy accident, suddenly these two guys had made contact. Pablo had been toiling away on a research project on persuasion and he meets a guy who's made that topic his career. They talked during breaks at this conference where Pablo shared his studies and Rich gave him some ideas for designing a new study and the hatched a plan to collaborate. As a first step Rich sent Pablo some light reading, but this was the 90s. So emailing a bunch of PDFs was out of the picture. Instead, he sent photocopies of the original papers. And he put that into a very heavy package and mail it by plane. It took a bunch of days to arrive in Madrid. So the idea was that he was going to send me the material. I was going to run the studies and that will buy me the opportunity to go to Columbus, Ohio State. The study they were designing was a quirky one. There's research in psychology on something called embodiment, which means that the physical cues we get from our own bodies can shape our psychology. Put your hands on your hips, puff out your chest and you'll feel more powerful. That kind of thing. In this case, the body cues come from your head, not your brain, your literal head. It's ingrained in us, at least those of us in a particular cultural environment, that nodding your head up and down is associated with yes. Whereas shaking your head back and forth is associated with no. So what happens if you nod or shake your head while listening to a persuasive message, would that change its persuasiveness? That's what they wanted to test. But of course, you don't tell people to nod their head that could tip them off to your idea. Instead, they told a bunch of college students that they were testing a new product, a pair of headphones. And part of this testing was that they wanted to know whether they were good for people under different movements and when they were just doing different things. So sometimes they asked people to wear the headphones as they tracked a spot on the computer screen going up and down and sometimes they asked them to do the same with a spot moving side to side. Of course what this meant was that sometimes students' heads were nodding up and down as they tracked the spot while listening to something on the headphones and sometimes their heads were shaking back and forth. And of course, the headphones were playing a recorded message about an issue at the students' university. But here's the other wrinkle. Sometimes the message playing on the headphones gave a bunch of strong compelling arguments to support the issue. But other times the message gave a bunch of weak arguments instead. Pablo and Rich had a few predictions about what would happen, but we did not quite saw this one coming. So during nodding, people were better, better not discriminating between the strong and weak arguments compared to shaking. You might think that maybe nodding your head up and down just makes you more agreeable. Like you're saying yes to the message, but that's not quite what happened. Instead when people nodded their heads, the strength of the arguments began to matter more. Meaning people could become more persuaded if the message was strongly argued, but nodding could make people less persuaded if the arguments were weak. On the flip side, the arguments didn't seem to matter so much when people were shaking their heads. Who was weird? That led us to a lot of speculation about what it could be. OK, I'll cut to the chase. Here's the explanation they came up with. Remember, the elaboration likelihood model is based in part on so-called cognitive responses, the thoughts that occur to you when you think about a message and strong arguments make you think of positive supporting thoughts. But weak arguments make you think of negative critical thoughts. So maybe nodding your head doesn't feel like saying yes to the message, but it's like saying yes to yourself, feeling like the thoughts that are occurring to you are valid. This would mean that nodding during a strongly argued message makes it more persuasive, because you're saying yes to the positive thoughts that occur to you, but nodding during a weak argued message makes it feel less persuasive because you're saying yes to the negative thoughts. If I see a commercial that makes no sense, I might think to myself, "Gee, but that thing doesn't even work." If I'm nodding my head, it's like I'm saying, "That's right, I really don't think this thing will work." And on the other hand, if I'm shaking my head, it's like I'm casting aside my own reactions as invalid those positive thoughts from the strong message, those negative thoughts from the weak message, shaking my head is like I'm saying none of my reactions should really be trusted. That's why the strength of the arguments didn't matter as much when people were shaking their heads because people set aside their own reactions, good or bad. They had stumbled on a new process in the elaboration likelihood model. If people are likely to elaborate on a message having thoughts in response to the message, then aspects of the persuasion environment could serve to validate those thoughts. They called it the self-validation hypothesis. Self-validation is about what you do with those thoughts that you already have. So thinking about your own thoughts, whether your thoughts are considered to be valid or not. And it's not just about nodding your head. All sorts of things can make your own reactions to a message seem more or less valid. Like take our old friend source credibility. Let's say you read a really convincing article about how blueberries are the healthiest fruit. It's full of strong arguments that make you think, "Wow, this is really convincing." And so you'd probably come away with a more positive impression of blueberries. Now imagine, after you read this article, you found out that it was written by the top health scientist in the world, a very credible source. Well, that should validate your reactions. You would feel more confident in the thoughts you had, so you'll be especially persuaded. But now imagine instead that after you read the article, you actually found out that it was written by some high school social media influencer being paid by Big Blueberry to talk up blueberries, not a credible source. And so you may start to doubt those thoughts you had. Should you really have been so convinced? Did you miss something? Same message, same strong arguments. But this reveal undermines persuasion by invalidating your own thoughts. And there's about a zillion things that have been shown to work this way. Head nodding versus shaking, smiling versus groaning, using your dominant hand versus your non-thominant hand, having people engage in powerful postures, source variables, context to our variables, message variables, you name it. Okay, so to recap, messages don't change minds in just one way. There are lots of ways in which people shift their opinions in light of a message, but it's not a free for all. The elaboration likelihood model provides order to the chaos. It all depends on how likely a person is to spend their precious time and energy, carefully considering the message. When people are unmotivated or unable to think carefully about a message, they can still be persuaded. But it will be because there are simple cues that allow the person to quickly infer that they should agree with the message, or there are other features that just quietly rub off on the person's opinion by association. This is like when a friend recommends a movie. It could just be that we like and trust our friend, so we can take their suggestion even without much thought. When people are motivated and able to think about the message though, persuasion can result from three different processes. First, we're persuaded by how compelling the message arguments are. This can be for plenty of reasons, but if the message gets us thinking thoughts that support the message, that's a good sign for persuasion. But if the message gets us thinking critical thoughts, counter-arguing the message and pushing back, well, not so great for persuasion. The other thing that can matter when we're thinking is that our thinking can be biased by some aspect of the message. The arguments are not completely strong or weak, but there's something else to not just, like if the message comes from someone we trust or distrust, we can start selectively thinking in supportive or critical ways. And we end up with opinions that feel like they're the result of careful thinking. And the final thing that could matter when we're thinking is that our thoughts can be made to feel valid or invalid as inputs into our opinions. If we've already spent the energy to think carefully about a message, other information, like signs of confidence we get from our own bodies or information about the communicator, those can still turn the tides on persuasion. It's actually pretty remarkable. Most of this model was spelled out in the 1980s by Rich Petty and John Casio Poe with that new wrinkle in the early 2000s with Pablo Bernoule. And it's remained pretty solid. New articles written about this model today look pretty similar to those original work ups. And a ton of studies have emerged over time that lend support to it. And I'm not trying to say it's perfect. It's had its critics. Like some have argued that the elaboration likelihood model complicates what is really just a simple process of translating information into opinions. Others have split hairs about exactly how to categorize the various processes. And some have criticized the model for being a little cagey as to what exactly is the difference between strong and weak arguments. But you can argue that the proof is in the pudding, as they say, and the elaboration likelihood model has inspired a lot of research by a lot of people in a lot of disciplines. And I'm biased, but it seems like it's done its job. Here's Pablo Stake. He replicates his very precise and it tells you what to expect when I'm for whom. So it's very parsimonious, very elegant. It's a little complex at first. But it is just very precise. I find it beautiful. And for such an influential set of ideas in psychology, it could have just as easily not happened. Like when Rich was looking for an advisor and Bob Chaudinie just happened to have arrived as a visitor to Ohio States. You have to think, well, what if Bob wasn't there with that particular study and we didn't do that particular study later? So these ideas probably still would be floating around, right? And he happened to meet John Casuapo and they had to study for a confusing exam. The side benefits of studying, for exams. And meeting Pablo in Spain, whose confusing study launched a new wave of research. If he hadn't come to this conference and if the translator hadn't left and so forth. Listen, I think Richard is one of the smartest people I've ever seen. know and I would not be who I am today without his influence. But I don't know it's helpful to know that his particularly successful career wasn't some grand plan he cooked up as a grad student in the 70s. You just never really know where things are headed and what spark of inspiration is coming next. But if you're curious and you're committed to figuring out that next puzzle and figuring it out to its absolute fullest, you'll be ready to go where you go. I hope I've at least persuaded you of that. All righty that'll do it for another episode of opinion science. Look I get that there was a long break in the podcast since the last episode but I had been sitting on these interviews with Rich and Pablo for a few years and I always wanted to make the hundred episode of this podcast and elaboration-likelyhood special. So I took some extra time to regroup and get the job done and we're back now. I've got more episodes ready to go and I'm excited for you to hear them. Next time on the show though you can hear the full interview with Rich Petty. There's a lot of stuff that just didn't fit into this episode because it goes a little deeper than I wanted for this overview of the ELM but more great stories and ideas are in that full interview so keep an ear out for that. I'm also going to change up the release schedule for this podcast a little bit but more on that next time. In the meantime thank you to the voices you heard Rich Petty, Pablo Brunel and Bob Chaudini. More info about them can be found in the show notes for this episode. For more about this show in general make sure you're subscribed to opinion science wherever you get podcasts so you don't miss anything. Go to opinion science podcast.com for past episodes and other fun stuff. There are a hundred episodes of this thing now so there's plenty to catch up on and you know it would be great if you could leave a review of this show someplace like Apple podcasts. They say reviews boost a podcast's visibility but you know what they also make me feel good. Produced all 100 episodes of this show on my own so those reviews really make my day. Okay that's all for now. Thank you for listening and I'll see you in a couple weeks for more opinion science. Oh oh and just one more thing. Here's my favorite part of the why we fight film. It's this old British lady sitting on a bench next to her husband who seems to have no idea he's being filmed but nevertheless this woman is giving her powerful inspirational speech. We've been bombed, dive bombed, high level bombed, machine gun, been through a ton of Asian scares. The last lot we had we had the house down about 30s but we are still sticking it and we're going to stick it. Okay see you next time.