steve's primer of practical persuasion version 2.0
Elaboration Likelihood Model: Hmmmm, I’m Thinking . . . Maybe
How do you get others to change?
Since recorded history, people have tried to answer that question. The attempt has occupied the time and efforts of some of the best minds civilization has produced. Frankly, no one has yet discovered the ultimate and final answer to the question. We truly cannot explain all the causes and consequences of influence in a way that satisfies most people most of the time.
As a result, if you take the time to read widely in this area, you will be struck by the diversity and range of answers that thinkers have given to our question. If you have even taken a moment to scan this book, you were probably surprised at the number of different approaches. How can we organize all these different ideas?
In this chapter you will find the current answer to this question. The main point of this new approach is aptly suggested the subtitle of this chapter, "Hmmm, I'm thinking, maybe." The Elaboration Likelihood Model (ELM) claims that a person's route of thinking determines influence. We are going to use the ELM as our major blueprint in this book, so pay close attention to this chapter. You may want to read it carefully a couple of times to make sure you've got it.
Assumptions of the Elaboration Likelihood Model
The ELM is quite simple and based on four assumptions about people and influence. Let’s take the four assumptions in one fell swoop, then we’ll detail them. First, consider a diagram:
Okay, that "mental state" concept controls selection. If you're high WATT, then one thing happens, but if you are low WATT, then something else happens. Or developed through the assumptions . . .
1: There are two routes of thinking that a person may employ.
2: Situational and personality variables affect which route of thinking a person will employ.
3: Persuasion tools will have different effects depending upon the route of thinking employed.
4: Influence achieved through the central route is more persistent over time, more resistant to change, and more predictive of behavior than influence from the peripheral route.
Just mull these over for a second and open up a mental landscape for them. Two routes of thinking . . . situation and personality determine which route . . . different tools have different effects depending on route . . . outcomes vary with route. Huh, this “route of thinking” idea gets repeated a lot, doesn’t it?
Assumption 1: There are two routes of thinking that a person may employ.
One route is called the "central" route and the other is called the "peripheral" route. The central route refers to a person who is carefully and effortfully thinking. The thought process is active, creative, and alert. The peripheral route, by contrast, is at the other extreme of thinking. Here the person is not really thinking very carefully and instead is skimming along the surface of ideas. They are thinking enough to be aware of the situation, but they are not thinking carefully enough to catch flaws, errors, and inconsistencies in the situation.
The big distinction between the two routes is the amount of - hold on cause I can’t avoid this - elaboration activity. People on the central route engage in a lot of elaborative processing while people on the peripheral route don’t. Stated another way, people on the central route think more thoughts about the situation than people on the peripheral route. Consider this example.
Peripheral Shopper is looking for a bottle of spaghetti sauce in the grocery store. PS finds a large rack filled with many different brands, prices, and sizes of bottles. Reaching forward, PS grabs one, thinking “Gee, that a pretty red label, I’ll bet it tastes good.”
Central Shopper, waiting impatiently behind PS, scans the large rack of spaghetti bottles with the cold and calculating eye of poker champion. As PS ambles down the aisle, CS steps forward with great concentration, thinking, “. . . yes, but the sodium content is probably off the chart, so what about percentage of tomato, all that lycopene, a natural anti-oxidant, but look at the price, good grief, you could buy a peck of tomatoes for that price, but then you’d have to clean the tomatoes yourself, then cut them and lose a finger, plus who knows what kind of pesticides they used on the tomatoes and I don’t even what to think about those greedy corporate farms that pay slave wages, . . .”
We all have an ongoing conversation running in our heads. On any given topic, sometimes the conversation is short and sometimes it is long. Sometimes the content of the conversation is relevant, sharp, focused, balanced, analytic, articulated, and thorough. Sometimes the content of the conversation is just plain simple. When these thoughts are about the persuasive situation, the conversation is called, elaboration activity. To elaborate means to add, extend, go beyond what’s given. In the shopping example, the Central Shopper obviously generated a lot of elaborations with considerations of health, price, and effort. The Peripheral Shopper also thought about the situation, but with fewer elaborations and elaborations that were not exactly crucial (sauce in a bottle with a “pretty red” label will taste better?).
Let’s make two sharp points of exception right now.
1. Just because the conversation is short doesn’t mean it is always peripheral. “They all taste the same to me, give me the cheapest” is a short conversation, but it is central. Sometimes central route thinking is shorter because it cuts right to chase and finds the key element that determines the attitude.
2. Just because the conversation is long, doesn’t mean it is central. If the thoughts are irrelevant to the situation, it doesn’t matter how many of them you generate. If our shopper is having a great and involved conversation that includes humming along to the music and remembering that time back in high school and wondering what happened to that fabulous blonde and that one date, wow, then, oops, walked past the spaghetti sauce, isn’t that on the list, hey, that red label looks good, I’ll bet that is great tasting . . . you’ve got a long peripheral conversation. (I wonder? What did happen with that blonde?)
With these caveats in mind realize that when we are on the central route we will tend to have a longer conversation in our heads and that the content of the conversation will contain many topic relevant thoughts. By contrast when we are on the peripheral route we will tend to have shorter conversations and the content will contain more irrelevant thoughts.
In summary, then, people can employ one of two distinct routes of thinking, central and peripheral. Central routes are characterized by longer conversations with lots of relevant content. Peripheral routes tend to have shorter conversations with irrelevant content.
Assumption 2: Situational and personality variables affect which route of thinking a person will employ.
People are flexible can move back and forth between the two routes. Sometimes we are central and other times we are peripheral. (It is easy to confuse routes of thinking with intelligence as if smart people are central and dumb people are peripheral. While there is overlap, keep the concepts clean and separate. Smart people amble down the peripheral route all the time. Dumb people can focus their more limited resources and take the central route when needed.)
The route we use depends on situational and personality factors. For example, if the situation has strong personal relevance for us (imagine you see an editorial entitled, "Should People Be Executed for Reading Practical Persuasion Books”), chances are we will use the central route of thinking. Now, if the situation has little relevance to us (you see an editorial entitled, "Should People Be Executed for Watching Bad Movies"), chances are you will use the peripheral route of thinking as you read the editorial. Situational factors manipulate the route.
People also have strong individual preferences for particular routes of thinking. Some people have a high need for cognition and typically think carefully about things most of the time. There is even a scale to measure this (do a search on “Need for Cognition Scale”). By contrast some people have a low need for cognition and typically think as little as possible about a situation. In between are most people who are more sensitive to situational factors. Again, there is a tendency to equate this individual difference with intelligence. Yes, people who are smarter also tend to like to think a lot about virtually everything, including spaghetti sauce. But simply because you are thinking a lot doesn’t mean you are smarter. (Hey, increase your IQ score by thinking more thoughts as you take an IQ test! Notice the color or tone of the paper, the typeface, the spacing format, count the number of words in the question, compare the proportion of vowels and consonants, yeah, that’s the ticket.)
Thus, our route of thought can be driven by the situation or our personality predispositions. Note that even people who prefer to be peripheral thinkers can still shift into the central route when the situation calls for it.
Assumption 3: Persuasion tools will have different effects depending upon the route of thinking employed.
When people are taking the central route, certain things will be very important and influential to them. While reading that editorial on executing persuasion readers, the central thinker will be looking for facts, evidence, examples, reasoning, and logic. We will call these things, "arguments."
By contrast, when people are taking the peripheral route, other things will be important. Since arguments (facts, evidence, reasoning, etc.) require a lot of cognitive effort and energy, the peripheral thinker won't use them very much. Instead, easier to process information will be employed. Things like the attractiveness, friendliness, or expertise of the source will be more influential for the peripheral thinker. We will call these things, "cues." Thus, there are two persuasion tools, arguments and cues.
Thus a smart persuasion source will be generous with the cues if the receiver is low WATT and by contrast bring on the arguments when the receiver is high WATT. A dumb persuasion source will bullheadedly persist with arguments in the face of a low WATT processor or just as bullheadedly persist with cues given a high WATT processor. In other words, smart persuaders match the right persuasion tool, argument or cue, with the right mental state, high or low WATT. Dumb persuaders mismatch tool and WATTage.
Okay, now let’s get a little tricky. Imagine you see an advertisement in a magazine. It features a physically attractive blonde with very long wavy hair that is blowing in the wind. The blonde is holding the wheel of a sporty red convertible. The caption for the ad claims: For Beautiful Hair.
Now, take the same ad, but let’s change the product. Now our blonde with the very long wavy hair is holding a bottle of shampoo. The caption reads: For Beautiful Hair.
In both ads we’ve got the same “message.” A physically attractive blonde with long wavy hair is holding the product with the same caption. But, it should be clear that in the car ad, the blonde is functioning as a cue (buy this car for better hair!?!) while in the shampoo ad the blonde is functioning as an argument (buy this shampoo for better hair). Thus, the same variable can actually accomplish different persuasion goals depending upon the situation.
And just to really confuse you, think about this. I use a lot of blonde examples in the Primer. Guess what? My wife is the girl of my dreams and I fell in love with her the instant I saw her. She’s a blonde. After twenty five years of marriage, I’ve learned to pay attention to blondes moving around in my environment. It might be my wife, right? Thus, if I catch a blonde out of the corner of my eye, I focus my attention, however briefly, in that direction. In ELM terms, my WATTage goes up with blondes. (Should I rephrase that?) So now, you've got an illustration of the same variable (blondes) that can function as an argument, a cue, or an elaboration moderator.
This assumption is very important, because it suggests that there is no single factor (or list of factors) that is a surefire path to success. Depending upon the receiver's route of thinking, some variables will work and others won't.
Assumption 4: Influence achieved through the central route is more persistent over time, more resistant to change, and more predictive of behavior than influence from the peripheral route.
When people are thinking centrally, if they do change, it is more likely to stick precisely because they thought about it more carefully, fully, and deeply. For peripheral thinkers, however, any influence is likely to be rather short lived, simply because they did not really think that much.
Now, here's a real interesting point. These assumptions say nothing about magnitude differences. There is no claim made that the central path leads to more attitude change or influence in the short term compared the peripheral path or vice versa. This means that regardless of path, we can get the same amount of change in a receiver. Thus, in the immediate, short term situation, whether the receiver is central or peripheral, whether we provide arguments or cues, we can still get the same magnitude or amount of influence. This is very important to remember. Both paths can lead to the same amount of influence. Persistence, resistance, and prediction, however, favor the central route.
Let's take the assumptions and arrange them in a visual display.| Central Route | Peripheral Route | |
| Thinking Mode | hi WATT | lo WATT |
| Influence Tool | arguments | cues |
| Magnitude | equal | equal |
| Persistence | longer | shorter |
| Resistance | stronger | weaker |
| Prediction | higher | lower |
Are There Really Only Two Routes?
The assumptions of the dual process approach make it sound like there is this little mental switch inside us that moves us from one track to another. Are there really only two routes of thinking? Is there nothing in between?
These are interesting questions and most current research seems to say that there are only two routes with nothing in between. This approach certainly simplifies the theory and, believe it or not, there is some pretty good evidence to suggest that people really do have only two routes of thought. But catch a key point here.
Please realize that the kind of persuasion we are talking about here is that immediate, here-and-now, dynamic, flow of life, it only happens once and it is happening right now, you only get one chance to make a first impression, kind of persuasion. Realize that life is made of up all of the moments and that we hold all of these events in our memories, saving them for use in later times. Thus, at this moment we are centrally processing an argument about voting for a candidate and then at another moment we are peripherally processing a cue about voting for the same person. In each situation we can clearly see the operation of only one route, central or peripheral. However, if we think about the total experience of the person in regards to that candidate, their beliefs and attitudes were created by the combination of these central and peripheral experiences.
Researchers have made a very useful bifurcation in the central route. Several studies and common sense thinking reveal that central route thinkers may be on two different sub-routes, either Objective or Biased. Objective route thinkers do all of that effortful elaboration activity, but it is driven by the quality of the arguments. By contrast, Biased route thinkers engage in elaboration activity, but the thoughts are controlled by an existing bias.
Let’s pull on this distinction a bit. Objective thinkers are doing the best they can to determine the “truth” of the persuasive situation as closely as it is possible to determine the “truth.” Which candidate should you vote for in the next election? While the answer to that question is not as simple and unambiguous as “What does 2 + 2 equal?” it is possible to make voting selection a highly rational and empirical process. Objective thinkers do their best to find all of the relevant information under these uncertain conditions and if not find the “true” answer, at least find the “best” answer.
By contrast, the Biased thinker will not follow the data wherever it leads, but rather will tend to select arguments and generate elaborations that are congenial to an existing bias. In our election example, if you were raised in a conservative household, chances are pretty good that you already hold favorable beliefs and attitudes towards candidates with a conservative orientation. When you think about the next election when you think about the candidates you will unconsciously tend to pick arguments that bias toward the conservative. For example, you’ll look for candidate voting records only on the conservative positions (foreign policy, free markets) and ignore more liberal positions (human rights, international cooperation). And, even though the Biased thinker is carefully and effortfully elaborating on arguments, the deck is a bit stacked in favor of an existing position.
Quick summary: There are two Big routes: Central and Peripheral. Within Central route there are two sub routes: Objective and Biased. Both Objective and Biased processors are thinking in contrast to Peripheral processors who are more top of the head. However, Objective and Biased thinkers use their cognitive resources in very different ways. Objective processors try to follow the trail of arguments wherever they lead while Biased processors try to make the trail lead to a predetermined position.
How Do You Shift Routes?
This is a million dollar question.
We realize that central thinkers want arguments and peripheral thinkers want cues. We also know that central thinkers, if they are influenced, will show changes that are more persistent, resistant, and predictive. How do we get people to take the central route?
First of all, a lot of research and simple common sense indicates that most people most of the time are in the peripheral route. They are sometimes called, "cognitive misers." Less politely, it means that people are lazy thinkers who do not want to expend the energy needed to think carefully and effortfully about something.
If you don't believe me and think that people are instead usually central thinkers, I have a task for you. Stop reading this chapter right now and go over to the TV. Turn it on and watch only the commercials for a while. For the overwhelming majority of ads, how much thinking do you have to do? That's right, not much. Now, if people were usually in that central route, advertisers would not show the kind of commercials we see. Ads are long on cues and short on arguments.
People think enough to meet the minimum demands of the situation. That is the status quo and it means we spend most of our time on the peripheral route. But as a practical persuader, we have a different agenda. We want our targets to change and we want that change to last. That means central thinking, which returns us to the million dollar question.
Quite surprisingly, there are many ways to get central thinking (and if you want to read more about it do a search on “elaboration likelihood”). The best way to get a handle on these mental switches is to think about two big categories: Motivation and Ability.
If you want to increase the likelihood of central processing you must make sure that your target is Motivated to do this kind of cognitive work. Central processing by definition takes more concentration and effort than usual. When you want people to work harder, you must motivate them.
The best example of a factor that motivates is relevance. When people believe the situation is personally important to them, they are much more likely to think centrally about it. If the situation holds little relevance, they will stay in the peripheral route. Thus, you must demonstrate how the issue is meaningful and relevant to your targets if you want them to be central thinkers. In other words, your targets must be motivated to think.
The second factor you need to consider is Ability. When people have the ability to work harder, it is more likely they will do so. What makes people better able to think harder? Hey, if you’re selling your product to a mass audience that includes Hispanics, you might consider writing some of your ads in Spanish. If you are selling a high tech product to a group of low tech buyers, you might translate your PowerPoint presentation from Scientese into Just Folks.
Basically, what we are talking about here is comprehension. Can your target understand what you are talking about? Now, don’t give me any lip about this and tell me sad stories about stupid customers, clients, suppliers, friends, or family. You are trying to persuade them. If they don’t change, you did something wrong. When a source presents information that is complex, dense, abstruse, recondite, esoteric (I'm running out of entries in my thesaurus!), in other words when receivers have to work too hard to understand, they will not centrally process the information. Instead they will drop back into a peripheral route. In essence, you must make sure that your targets have the ability to think about the issue.
What’s The List Of Arguments And Cues?
Once we have established the route, we have to provide the correct influence agent. If we get the right match between route and agent, we are successful. If we get the wrong match, we have a problem.
Central thinkers want arguments. It should be easy to produce lists of arguments and away we go. But, hold on a minute and think about this.
Your teenage son needs a new pair of sneakers. Assume that both you and your son are going to be central thinkers as you decide which sneakers to buy. Okay, you're both central thinkers, so that means you both want arguments. From your point of view, what are the arguments you consider as you choose between the various sneakers?
How much do they cost?
How long will they last?
Is the store nearby?
Now, consider the list of arguments from your teenager's perspective.
Who endorses them?
Do all the other guys wear them?
Would that great looking girl go out with me if I had 'em?
You see the problem. Arguments depend upon the receiver. Thus, to develop a list of arguments for any given persuasion situation requires some careful thought on the part of the persuasion source. In essence a persuasion source asks this question: What is of central importance to the receiver?
If you can figure out the answers to this question and the receiver is in the central route, then you will be effective as a persuader. You will also generate persistent, resistant, and predictive attitude change.
This is an important point and I want to give you an example to illustrate the "relative" meaning of arguments. The example concerns teenagers and smoking. In the past, persuasion sources (parents, teachers, the federal government) have tried to prevent teenage smoking with arguments based on health ("smoking causes cancer"). And despite the best efforts of all concerned, teens continued to smoke. Why? The health argument lacks central importance to a teenager. Teenagers still embrace the myth of immortality and they know they will live forever, maybe even to forty. Threats about cancer and death are empty.
New approaches use different arguments and have shown better results. The new arguments are based on social factors ("you smell bad if you smoke," "no one wants to kiss somebody with cigarette breath") and more lately on control factors (“greedy tobacco companies are manipulating you”). Peer acceptance and independence are of central importance to teens. These arguments appear to be more powerful to teenagers and hence produce the kind of change we prefer.
The main point is this: There is no cookbook list of arguments because argument quality depends upon the receiver. To produce good arguments, you must understand your receivers and be able to think the way they do.
Watch the beer commercials on TV for the answer. Young, attractive women wearing skimpy bikinis are among the dominant images on these ads. No reasonable person would ever claim that these young women are arguments for the beer. (Unless the receiver really believes that the girl comes with the case.)
Well, then maybe those girls are simply used to get the receiver's attention and make them central thinkers about the beer ad. If you believe that, I've got a bridge you might be interested in. Half naked women do not encourage central thinking about beer.
The only thing we are left with is a cue. People (usually men) watch the beer ad and see the attractive girls. The men like this in a way that requires little thinking on their part. And they simply associate that good feeling with the beer and voila, influence without thought.
But does it work?
Bet the ranch on it. The effects of attractiveness on the peripheral processor are very powerful.
Here are more quick examples.
Ever been to a Tupperware party and ended up buying something you don't really need or want simply because you see you other friends buying things?
Have you ever seen a good kid do something really stupid just because the peer group expects it?
There are many other cues. (If you can’t wait, go to CLARCCS Cues.) There are a lot of persuasion cues and we will discuss them throughout the rest of this book. In fact, cues are so important I offer this rule:
When in doubt, take the peripheral route or
What to do? Use a Cue.
Practical Implications
The dual process model has three important implications for us. While the model sounds abstract, it does apply to our everyday life in practical ways. Consider these ideas.
1. Monitor and control the mental state.
This is a major point. Persuaders who are adept at reading their targets are much more likely to be effective persuaders. But how can you tell which mental state your target is in? There are two primary areas to look at.
First, observe the nonverbal behaviors of your targets. Generally speaking, if you observe behaviors that indicate attentiveness, alertness, and thoughtfulness, you can begin to assume those targets are in the central route. As you see behaviors that demonstrate distraction, boredom, or laziness, you can assume that they on the peripheral route.
Second, simply ask questions. Get your targets to respond. Then judge the quality of the responses. Do they sound thoughtful and reasonable? Or instead, do they ask you to repeat the question or give answers that are off the wall?
When people are on the central route they look and act differently than when they are in the peripheral route. Learn to get a sense of this by observing your targets. It will make you a nicer person, too.
2. Match the right influence agent (arguments or cues) with the correct mental state (central or peripheral).
You don't need an umbrella on a sunny day and peripheral processors will not heed arguments. You have to identify correctly what the receivers mental state is and then provide either arguments or cues.
In most situations most of the time with most people, they ambling along the peripheral route. They are not focused like a laser beam on every element of their environment carefully considering the pros and cons, the costs and benefits, the profits and losses of those elements (“Yes, it tastes great, but is it really filling!”). Again, if you don’t believe me, just look at any kind of advertising. Really look around a mall or a busy shopping district. Look at TV or Internet ads. Overwhelmingly, you see cues. It’s not even close.
This is not to say that we should not use arguments in most ordinary circumstances. As we have already developed, when people systematically think about persuasion arguments, the influence will last longer, be more resistant to change, and motivate behavior. We want that kind of change. But first you must make sure that your targets are willing and able to do the needed thinking. If you cannot assure yourself that your receivers are in such a frame of mind, it is useless and frustrating to try and influence with arguments.
3. Develop arguments from the point of view of the receiver.
Okay, we need the obligatory example of some bonehead play. How about something from long ago and far away?
During the mid-1980s (shortly after hamburgers were invented), Burger King spent millions of dollars on a major advertising campaign. The purpose of this campaign was not merely to sell a few more burgers, but to challenge McDonald's for leadership in the very competitive fast food market. Burger King did a lot of careful planning, a lot of quiet pretesting, and then unleashed its ad attack.
The campaign was built around a character named Herb. Herb was a balding, thin fellow, who wore glasses, black pants that were too short, and white socks. Herb was supposed to be a whimsical sort of Everyman that we could all identify with.
It didn't work.
No one identified with Herb and in fact there were a lot of Herb jokes. The ad campaign totally backfired on Burger King and actually had the effect of selling fewer burgers. The campaign, which was to run for over a year, was killed in a month. Somehow, Burger King had terribly misunderstood the market and had produced messages that no one found to be compelling or influential or even enjoyable.
(Gee, do you think I’ll get any phone calls from Burger King inquiring after my extraordinary consulting services? They’ll probably plaster my face on Wanted Posters in every BK restaurant in the world. Imagine the kind of service I’ll get. Think what they’ll add to my sandwich order? Maybe I should use a McDonald’s example instead. Or something stupid that Genghis Khan did. Aren’t all the Khan people dead? Gee, specific examples sure spice up a book, but you can make somebody mad with ‘em. I’m not overthinking this, am I?)
We can do the same thing if we are not careful. Usually the worst arguments are precisely the ones we prefer. (Like the young boy who bought a special birthday gift for his mom: A catcher's mitt.) We offer arguments that are compelling and powerful to us. And, we tend to assume that other people will respond the same way. That's a bad assumption.
The best way to develop good arguments is to observe carefully your targets. Listen to them. Ask them about the music they like and the movies they watch. Pay attention to the clothes they wear and the language they use. People who tune into their targets will develop an intuitive sense of what makes a good argument and what makes a bad argument. You know that advertisers extensively pretest their commercials. It is no different for anyone else. Test your ideas on one or two folks before you run them with everyone.
Outro
The ELM is a very useful persuasion theory. As we’ll see through the rest of the Primer, it helps organize a lot of concepts (this will be very apparent in the CLARCC’S chapter and with the SMCR variable analytics.) It is also incredibly helpful as a practical persuasion blueprint. If you want to understand real, here-and-now, online persuasion, the ELM is a great place to start.
References and Recommended Readings
The primary scientific sources on Dual Process routes of Persuasion come from: 1) the team of Richard Petty and John Cacioppo and 2) from Shelley Chaiken. Professors Petty and Cacioppo developed the Elaboration Likelihood Model (ELM) while Professor Chaiken developed the Heuristic-Systematic Model (HSM). If you do an Internet search on their names, you will find more information than you can possibly want. (Each is among the most prolific and honored psychologists of the past thirty years.) I have drawn from both, but use the terminology from the ELM because I find that it tastes great and is less filling. If you are stone cold crazy for persuasion, I’d strongly recommend that you first think a little more about the priorities of your life and then if you’re still interested, go read the “Psychology of Attitudes,” authored by Professor Chaiken and her colleagues, Professors Eagly and Lieberman. It definitely tastes great and is incredibly filling.
Professor Chaiken’s theory is called the Heuristic Systematic Model (HSM). It is much more tightly focused upon cognitive activity and also develops several interesting and useful postulates about how and why people move between the two modes of thinking, heuristic or systematic. The ELM, by contrast, takes a much broader scope and tries to explain attitude change under conditions that include less cognitive activity. Both theories are “true” for what they do, so there is no need to chose between them. It’s kind of like arguing whether a curveball or a fastball is the “best” pitch. For my uses in the Primer, the ELM is more general, so it helps organize more information from other chapters.
If you want to take a walk on the strange side, you might also be interested in pursuing the controversies that have surrounded these two theories. You normally think of academic scientists as fairly calm, quiet, and reserved people who giggle over trigonometry problems and make jokes that no one gets. Not with this crew. The ELM in particular has generated conflict worthy of an Oliver Stone movie. Even scientists get passionate. Almost crusading.
Chaiken, S. (1987). The heuristic systematic model of persuasion. In M. Zanna, J. Olson, & C. Herman (Eds.) Social influence: The Ontario symposium, Volume 5 (pp. 3-40). Hillsdale, NJ: Erlbaum.
Chaiken, S., Liberman, A., & Eagly, A. (1989). Heuristic and systematic information processing within and beyond the persuasion context. In J. Uleman & J. Bargh (Eds.), Unintended thought, (pp.212-252). New York: Guilford.
Petty, R., & Cacioppo, J. (1986). Communication and persuasion: The central and peripheral routes to attitude change. Springer-Verlag: New York.
