Persuasion header image
The Nature of Attitudes and Persuasion

The Yale Approach

Congruity Theory

Cognitive Dissonance Theory

Social Judgment/ Involvement Theory

Information Integration Theory

Theory of Reasoned Action

Elaboration Likelihood Model


Congruity Theory

Congruity Theory - Overview 
Heider's Balance Theory
Osgood and Tannenbaum's Congruity Theory
Strengths and Weaknesses of the Congruity Theory
Figure 1

Osgood and Tannenbaum's Congruity Theory

One nice feature of Osgood and Tannenbaum’s (1955) Congruity Theory is that it is explicitly oriented to communication and persuasion. Their refinement of Heider treated the Other person (O) as a message Source. The attitude Object is a Concept, and the P in Heider’s balance theory is essentially the audience. They quantified two of the three relationships in Heider’s triad: the degree of liking of the audience for the Source (PO in Heider’s triad) and the audience’s attitude toward the Concept (PX in Heider’s theory). Both of these relationships were represented by a number (1-7) as well as a direction (plus or minus). Thus, Congruity Theory concerns situations in which a Source makes an assertion about a Concept, and the audience has attitudes toward the Source and the Concept. The only relationship that remains the same is that the assertion of the Source about the Concept is either positive (associative) or negative (disassociative). This theory holds that incongruity (like imbalance) is unpleasant and motivates audiences to change their attitudes.

A second improvement is that Congruity Theory offers a formula for predicting the direction and amount of attitude change (those who are interested in the details of the formula should consult the reading list). The main point here is that Congruity Theory proposes a formula that predicts the amount and direction of attitude change based on the audience’s attitude toward the Source and the audience’s attitude toward the Concept.

Congruity theory was tested using a variety of hypothetical situations. Subjects were given a long list of people (potential message sources, like President Eisenhower or Soviet leader Kruchev) and concepts (communism, democracy) and asked to report their attitude toward each one. Later, subjects would be told that Eisenhower or Kruchev had made a statement about a concept, like democracy or communism. Researchers wanted to explore every option, so some of the statements linked liked sources (Eisenhower) with liked concepts (democracy) and disliked sources (Kruchev) with disliked concepts: “Eisenhower says democracy is what made this nation great,” “Kruchev said communism is the best system of government.”  Other statements associated liked sources with disliked concepts (“Eisenhower said the benefits of communism are not appreciated”) and disliked sources with liked concepts (“Kruchev declared that democracy was more efficient than communism”). After reading these messages, the subjects’ attitudes toward the sources and the concepts were measured again. The data for their initial attitudes toward source and concept were put into the formula and then their new attitudes (after reading the message) were compared with the attitudes predicted by Congruity Theory.

Research revealed that Congruity Theory’s predictions were supported generally: attitudes did tend to change in the predicted direction. However, precise amounts of attitude change were often incorrect (
Osgood, Suci, & Tannenbaum, 1957). These experimental results led the theorists to propose two corrections to the formula. These corrections are called post hoc hypotheses because they do not arise from the theory, but from research conducted after the theory was stated. In a sense they are “band-aids” trying to fix errors in the theory’s predictions.

The first post hoc hypothesis is called the assertion constant. It holds that when a source makes an assertion about a concept, that assertion tells us more about the concept than about the source (because, presumably, people are more complex than things). Accordingly, it predicts that attitude toward the source will not change as much as the formula predicts. So, when Eisenhower makes a statement about democracy, our attitude toward Eisenhower (as well as our attitude toward democracy) is likely to change, but our attitude toward Eisenhower will not change as much as the formula predicts. Because this hypothesis was developed after looking at the results of their research, it is of course supported by that research. Attitudes toward the sources of messages change, but less than attitudes toward concepts.

The second post hoc hypothesis is called the correction for incredulity. The researchers noticed that when a source was made to same something unreasonable -- like Eisenhower praised communism or Kruchev denounced communism -- attitude change predicted by Congruity Theory did not occur. So, the theory was amended again to say that the predictions would not work when a source says something that the audience does not believe that source would really say.

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