Cognitive dissonance is an uncomfortable feeling caused by holding conflicting ideas simultaneously. The theory of cognitive dissonance proposes that people have a motivational drive to reduce dissonance. They do this by changing their attitudes, beliefs, and actions. Dissonance is also reduced by justifying, blaming, and denying. It is one of the most influential and extensively studied theories in social psychology.
Experience can clash with expectations, as, for example, with buyer's remorse following the purchase of an expensive item. In a state of dissonance, people may feel surprise, dread, guilt, anger, or embarrassment. People are biased to think of their choices as correct, despite any contrary evidence. This bias gives dissonance theory its predictive power, shedding light on otherwise puzzling irrational and destructive behavior.
A classical example of this idea (and the origin of the expression "sour grapes") is expressed in the fable The Fox and the Grapes by Aesop (ca. 620–564 BCE). In the story, a fox sees some high-hanging grapes and wishes to eat them. When the fox is unable to think of a way to reach them, he surmises that the grapes are probably not worth eating, as they must not be ripe or that they are sour. This example follows a pattern: one desires something, finds it unattainable, and reduces one's dissonance by criticizing it. Jon Elster calls this pattern "adaptive preference formation."
The most famous case in the early study of cognitive dissonance was described by Leon Festinger and others in the book When Prophecy Fails. The authors infiltrated a group that was expecting the imminent end of the world on a certain date. When that prediction failed, the movement did not disintegrate, but grew instead. By sharing cult beliefs with others, they gained acceptance and thus reduced their own dissonance (see further discussion below).
I did not ... aim at gaining his favour by paying any servile respect to him but, after some time, took this other method. Having heard that he had in his library a certain very scarce and curious book, I wrote a note to him, expressing my desire of perusing that book, and requesting he would do me the favour of lending it to me for a few days. He sent it immediately, and I return'd it in about a week with another note, expressing strongly my sense of the favour. When we next met in the House, he spoke to me (which he had never done before), and with great civility; and he ever after manifested a readiness to serve me on all occasions, so that we became great friends, and our friendship continued to his death. This is another instance of the truth of an old maxim I had learned, which says, "He that has once done you a kindness will be more ready to do you another, than he whom you yourself have obliged."
This perception of Franklin has led to what has become known as the Ben Franklin effect. After lending Franklin the book, the opponent had to resolve the dissonance of his attitude towards Franklin, whom he also had just done a favor. He justified doing the favor by telling himself that he actually liked Franklin, and, as a result, he treated him with respect instead of rudeness from then on.
Smoking is often postulated as an example of cognitive dissonance because it is widely accepted that cigarettes can cause lung cancer, yet virtually everyone wants to live a long and healthy life. In terms of the theory, the desire to live a long life is dissonant with the activity of doing something that will most likely shorten one's life. The tension produced by these contradictory ideas can be reduced by quitting smoking, denying the evidence of lung cancer, or justifying one's smoking. For example, smokers could rationalize their behavior by concluding that only a few smokers become ill, that it only happens to very heavy smokers, or that if smoking does not kill them, something else will. While chemical addiction may operate in addition to cognitive dissonance for existing smokers, new smokers may exhibit a simpler case of the latter.
This case of dissonance could also be interpreted in terms of a threat to the self-concept. The thought, "I am increasing my risk of lung cancer" is dissonant with the self-related belief, "I am a smart, reasonable person who makes good decisions." Because it is often easier to make excuses than it is to change behavior, dissonance theory leads to the conclusion that humans are sometimes rationalizing and not always rational beings.
An overarching principle of cognitive dissonance is that it involves the formation of an idea or emotion in conflict with a fundamental element of the self-concept, such as "I am a successful/functional person", "I am a good person", or "I made the right decision." The anxiety that comes with the possibility of having made a bad decision can lead to rationalization, the tendency to create additional reasons or justifications to support one's choices. A person who just spent too much money on a new car might decide that the new vehicle is much less likely to break down than his or her old car. This belief may or may not be true, but it would reduce dissonance and make the person feel better. Dissonance can also lead to confirmation bias, the denial of dis-confirming evidence, and other ego defense mechanisms.
Within this overarching principle, there are two main forms of dissonance: hedonistic dissonance and moral dissonance (Holland, Meertens & Van-Vugt, 2002).
- Hedonistic dissonance is elicited when people act in a way which results in negative consequences for themselves. For instance, a person is late for a meeting because of traffic but could have been on time had he taken the subway.
- Moral dissonance is aroused when people act in a way that causes negative consequence for others. For instance, cheating and lying.
 Theory and research
Most of the research on cognitive dissonance takes the form of one of four major paradigms. Important research generated by the theory has been concerned with the consequences of exposure to information inconsistent with a prior belief, what happens after individuals act in ways that are inconsistent with their prior attitudes, what happens after individuals make decisions, and the effects of effort expenditure.
 The Belief Disconfirmation Paradigm
Dissonance is aroused when people are confronted with information that is inconsistent with their beliefs. If the dissonance is not reduced by changing one's belief, the dissonance can result in misperception or rejection or refutation of the information, seeking support from others who share the beliefs, and attempting to persuade others to restore consonance.
An early version of cognitive dissonance theory appeared in Leon Festinger's 1956 book, When Prophecy Fails. This book gave an inside account of the increasing belief which sometimes follows the failure of a cult's prophecy. The believers met at a pre-determined place and time, believing they alone would survive the Earth's destruction. The appointed time came and passed without incident. They faced acute cognitive dissonance: had they been the victim of a hoax? Had they donated their worldly possessions in vain? Most members chose to believe something less dissonant: the aliens had given earth a second chance, and the group was now empowered to spread the word: earth-spoiling must stop. The group dramatically increased their proselytism despite the failed prophecy.
 The Induced-Compliance Paradigm
In Festinger and Carlsmith's classic 1959 experiment, students were asked to spend an hour on boring and tedious tasks (e.g., turning pegs a quarter turn, over and over again). The tasks were designed to generate a strong, negative attitude. Once the subjects had done this, the experimenters asked some of them to do a simple favor. They were asked to talk to another subject (actually an actor) and persuade them that the tasks were interesting and engaging. Some participants were paid $20 (inflation adjusted to 2010, this equates to $150) for this favor, another group was paid $1 (or $7.50 in "2010 dollars"), and a control group was not asked to perform the favor.
When asked to rate the boring tasks at the conclusion of the study (not in the presence of the other "subject"), those in the $1 group rated them more positively than those in the $20 and control groups. This was explained by Festinger and Carlsmith as evidence for cognitive dissonance. The researchers theorized that people experienced dissonance between the conflicting cognitions, "I told someone that the task was interesting", and "I actually found it boring." When paid only $1, students were forced to internalize the attitude they were induced to express, because they had no other justification. Those in the $20 condition, however, had an obvious external justification for their behavior, and thus experienced less dissonance.
In subsequent experiments, an alternative method of inducing dissonance has become common. In this research, experimenters use counter-attitudinal essay-writing, in which people are paid varying amounts of money (e.g. $1 or $10) for writing essays expressing opinions contrary to their own. People paid only a small amount of money have less external justification for their inconsistency and must produce internal justification in order to reduce the high degree of dissonance that they are experiencing.
A variant of the induced-compliance paradigm is the forbidden toy paradigm. An experiment by Aronson and Carlsmith in 1963 examined self-justification in children. In this experiment, children were left in a room with a variety of toys, including a highly desirable toy steam-shovel (or other toy). Upon leaving the room, the experimenter told half the children that there would be a severe punishment if they played with that particular toy and told the other half that there would be a mild punishment. All of the children in the study refrained from playing with the toy. Later, when the children were told that they could freely play with whatever toy they wanted, the ones in the mild punishment condition were less likely to play with the toy, even though the threat had been removed. The children who were only mildly threatened had to justify to themselves why they did not play with the toy. The degree of punishment by itself was not strong enough, so the children had to convince themselves that the toy was not worth playing with in order to resolve their dissonance.
 The Free-Choice Paradigm
In a different type of experiment conducted by Jack Brehm, 225 female students rated a series of common appliances and were then allowed to choose one of two appliances to take home as a gift. A second round of ratings showed that the participants increased their ratings of the item they chose, and lowered their ratings of the rejected item. This can be explained in terms of cognitive dissonance. When making a difficult decision, there are always aspects of the rejected choice that one finds appealing and these features are dissonant with choosing something else. In other words, the cognition, "I chose X" is dissonant with the cognition, "There are some things I like about Y." More recent research has found similar results in four-year-old children and capuchin monkeys.
 The Effort-Justification Paradigm
Dissonance is aroused whenever individuals voluntarily engage in an unpleasant activity to achieve some desired goal. Dissonance can be reduced by exaggerating the desirability of the goal. Aronson & Mills had individuals undergo a severe or mild "initiation" in order to become a member of a group. In the severe-initiation condition, the individuals engaged in an embarrassing activity. The group turned out to be very dull and boring. The individuals in the severe-initiation condition evaluated the group as more interesting than the individuals in the mild-initiation condition.
All of the above paradigms continue to be used in fruitful research.
Washing one's hands has been shown to eliminate post-decisional dissonance, presumably because the dissonance is often caused by moral disgust (with oneself) which is related to disgust from unsanitary conditions.
 Challenges and qualifications
Daryl Bem was an early critic of cognitive dissonance theory. He proposed self-perception theory as a more parsimonious alternative explanation of the experimental results. According to Bem, people do not think much about their attitudes, let alone whether they are in conflict. Bem interpreted people in the Festinger and Carlsmith study or the induced-compliance paradigm as inferring their attitudes from their behavior. Thus, when asked "Did you find the task interesting?" they decided that they must have found it interesting because that is what they told someone. Bem suggested that people paid $20 had a salient, external incentive for their behavior and were likely to perceive the money as their reason for saying the task was interesting, rather than concluding that they actually found it interesting.
In many experimental situations, Bem's theory and Festinger's dissonance theory make identical predictions, but only dissonance theory predicts the presence of unpleasant tension or arousal. Lab experiments have verified the presence of arousal in dissonance situations. This provides support for cognitive dissonance theory and makes it unlikely that self-perception by itself can account for all the laboratory findings.
In 1969, Elliot Aronson reformulated the basic theory by linking it to the self-concept. According to this new interpretation, cognitive dissonance does not arise because people experience dissonance between conflicting cognitions. Instead, it occurs when people see their actions as conflicting with their normally positive view of themselves. Thus, about the original Festinger and Carlsmith study using the induced-compliance paradigm, Aronson stated that the dissonance was between the cognition, "I am an honest person" and the cognition, "I lied to someone about finding the task interesting." Other psychologists have argued that maintaining cognitive consistency is a way to protect public self-image, rather than private self-concept. However, a recent result  seems to rule out such an explanation by showing revaluation of items following a choice even when people have forgotten their choices.
During the 1980s, Cooper and Fazio argued that dissonance was caused by aversive consequences, rather than inconsistency. According to this interpretation, the fact that lying is wrong and hurtful, not the inconsistency between cognitions, is what makes people feel bad. Subsequent research, however, found that people experience dissonance even when they feel they have not done anything wrong. For example, Harmon-Jones and colleagues showed that people experience dissonance even when the consequences of their statements are beneficial—as when they convince sexually active students to use condoms, when they, themselves are not using condoms.
Chen and colleagues have criticized the free-choice paradigm and have suggested that the "Rank, choice, rank" method of studying dissonance is invalid. They argue that research design relies on the assumption that, if the subject rates options differently in the second survey, then the subject's attitudes towards the options have therefore changed. They show that there are other reasons one might get different rankings in the second survey—perhaps the subjects were largely indifferent between choices. Although some follow-up studies have found supportive evidence for Chen's concerns, other studies that have controlled for Chen's concerns have not, instead suggesting that the mere act of making a choice can indeed change preferences. Nevertheless, this issue remains under active investigation.
 Cognitive dissonance in the brain
Using fMRI, Van Veen and colleagues investigated the neural basis of cognitive dissonance in a modified version of the classic induced compliance paradigm. While in the scanner, participants "argued" that the uncomfortable MRI environment was nevertheless a pleasant experience. The researchers replicated the basic induced compliance findings; participants in an experimental group enjoyed the scanner more than participants in a control group who simply were paid to make their argument. Importantly, responding counter-attitudinally activated the dorsal anterior cingulate cortex and the anterior insular cortex; furthermore, the degree to which these regions were activated predicted individual participants' degree of attitude change. Van Veen and colleagues argue that these findings support the original dissonance theory by Festinger, and support the "conflict theory" of anterior cingulate functioning.
Using the free choice paradigm, Sharot and colleagues have shown that after making a choice, activity in the striatum changes to reflect the new evaluation of the choice object, increasing if the object was chosen and decreasing if it was rejected. Follow-up studies have largely confirmed these results.
 Modeling in neural networks
Neural network models of cognition have provided the necessary framework to integrate the empirical research done on cognitive dissonance and attitudes into one model of explanation of attitude formation and change.
Various neural network models have been developed to predict how cognitive dissonance will influence an individual's attitude and behavior. These include:
- Parallel Constraint Satisfaction Processes
- The Meta-Cognitive Model (MCM) of attitudes
- Adaptive connectionist model of cognitive dissonance
- Attitudes as constraint satisfaction model
 See also
- Affective forecasting
- Buyer's remorse is a form of post-decision dissonance.
- Choice-supportive bias is a memory bias that makes past choices seem better than they actually were.
- Cognitive bias
- Cognitive distortion
- Cognitive inertia
- Congruence principle
- Cultural dissonance is dissonance on a larger scale.
- Double bind is a communicative situation where a person receives different or contradictory messages.
- Doublethink is a concept present in George Orwell's Nineteen Eighty-Four that allows a person to hold two contradictory ideas simultaneously and accept both of them as correct.
- Effort justification is the tendency to attribute a greater (than objective) value to an outcome which demands a great effort in order to resolve a dissonance.
- Emotional conflict is the presence in the subconscious of different and opposing emotions relating to a situation that has recently taken place or is in the process of being unfolded
- The Great Disappointment of 1844 is an example of cognitive dissonance in a religious context.
- Illusion-of-truth effect states that a person is more likely to believe a familiar statement than an unfamiliar one.
- Information overload
- True-believer syndrome demonstrates carrying a post-cognitive-dissonance belief regardless of new information.
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 Further reading
- Cooper, J. (2007). Cognitive dissonance: 50 years of a classic theory. London: Sage publications.
- Harmon-Jones, E., & J. Mills. (Eds.) (1999). Cognitive Dissonance: Progress on a Pivotal Theory in Social Psychology. Washington, DC: American Psychological Association.
- Tavris, C.; Aronson, E. (2007). Mistakes were made (but not by me): Why we justify foolish beliefs, bad decisions, and hurtful acts. Orlando, FL: Harcourt. ISBN 978-0-15-101098-1.