expectancy-value theory

n. Human beings have a natural tendency to react with some degree of positive or negative affect to any object or concept of psychological significance. We like or dislike certain people, support or oppose various policies, regard some activities as pleasant and others as unpleasant, have favorable views of certain institutions but unfavorable views of others, and so forth. Expectancy-value (EV) theory is, first and foremost, concerned with the origins and structure of these social attitudes. According to EV theory, the overall evaluation or attitude toward a psychological object is a function of the information or beliefs we have about the object in question. In the course of our daily lives our experiences lead us to acquire many different beliefs about various objects, actions, and events. These beliefs may be formed as a result of direct observation; they may be acquired indirectly by accepting information from other people or from printed and electronic media; or they may be self-generated through inference processes. Each belief associates the attitude object with an attribute. For example, we may come to believe that genetically modified food (the object) increases agricultural yields, contaminates the environment, and causes birth defects (the attributes). Because the attributes that become associated with the object are already valued positively or negatively, we simultaneously and automatically acquire an attitude toward the object. Specifically, the subjective value of each attribute contributes to the attitude in direct proportion to the strength of the belief, that is, to the subjective probability that the object has the attribute in question. The way in which beliefs about an object combine to produce an overall attitude is shown in the following:

A; \(\Sigma{b_i}{e_i}\)

It can be seen that the strength of each belief (b) is multiplied by the evaluation of the associated attribute (e), and the resulting products are summed over all beliefs about the object. According to the expectancy-value model, a person's attitude (A) is directly proportional to this summative belief index. In this fashion, we learn to like objects we associate with largely desirable characteristics and to form unfavorable attitudes toward objects we associate with mainly undesirable characteristics.

Of course, individuals are not expected actually to perform the mental calculations specified in the equation. The EV model is taken not as an accurate description of the way in which attitudes are formed, but rather it is assumed that the attitude formation process can be modeled as if individuals were performing the stipulated calculations. It is also important to realize that people can form many beliefs about any psychological object, but that only a relatively small number - perhaps 6 to 10 - are readily available in memory at any given moment. It is these readily accessible beliefs that are assumed to be the prevailing determinants of a person's attitude.

To acquire a good understanding of the factors that serve as the basis for existing attitudes, accessible beliefs about the attitude object are elicited in a free-response format. Individuals are asked to list any positive and any negative aspects of the object that come readily to mind. In most applications of the EV model, the most frequently listed responses are selected to construct a list of modal accessible beliefs, that is, beliefs that are common in the population of interest. Once a list of accessible attributes has been constructed, a new sample of participants are asked to rate the likelihood and the valence associated with each attribute. That is, they are asked to rate how likely it is that the object has the attribute (belief strength) and to rate the attribute on an evaluative scale (attribute evaluation). These two ratings are multiplied, and the products are summed in accordance with the preceding equation. In addition, as a direct measure of attitude, participants are also asked to rate the attitude object itself on an evaluative scale. In accordance with EV theory, empirical research has demonstrated strong correlations between this direct attitude measure and the summed belief x evaluation index.

In short, in EV theory it is assumed that our beliefs form the informational foundation for our attitudes. Although often quite accurate, beliefs can be biased by a variety of cognitive and motivational processes. They may be irrational, be based on invalid or selective information, be self-serving, or otherwise fail to correspond to reality. However, no matter how they were formed or how accurate they are, beliefs represent the information we have about the world in which we live, and they form the cognitive foundation for our attitudes toward aspects of that world.

However, expectancy-value theory can be used not only to account for the formation and structure of attitudes but also to help explain behavioral decisions. People form attitudes not only toward physical objects, institutions, social groups, events, and policies but also toward behaviors. Thus, we may hold favorable or unfavorable attitudes toward eating genetically modified food, drinking alcohol, exercising, participating in a demonstration, and so forth. When the object of the attitude is a behavior, the relevant beliefs that determine the attitude are readily accessible beliefs about the consequences of the behavior. These behavioral beliefs are again elicited in a free-response format, a list of modal behavioral outcomes is constructed, and participants are asked to rate the likelihood that the behavior will produce each outcome and to rate the valence of each outcome on an evaluative scale. Belief strength and outcome evaluation ratings are multiplied and the products are summed to produce the expectancy-value composite, which is again found to correlate well with a direct measure of attitude toward the behavior.

The EV model of attitude toward a behavior is a central factor in the theory of planned behavior (TPB), a popular model for the prediction of human social behavior. The theory has been used successfully in attempts to provide a better understanding of such diverse behaviors as exercising, donating blood, adhering to a low-fat diet, using condoms for AIDS prevention, using illegal drugs, wearing a safety helmet, and choosing a career, among many others.

Briefly, according to the TPB, human action is influenced by three major factors: a favorable or unfavorable evaluation of the behavior (attitude toward the behavior), perceived social pressure to perform or not perform the behavior (subjective norm), and self-efficacy in relation to the behavior (perceived behavioral control). In combination, attitude toward the behavior, subjective norm, and perception of behavioral control lead to the formation of a behavioral intention. As a general rule, the more favorable the attitude and subjective norm, and the greater the perceived behavioral control, the stronger should be the person^,s intention to perform the behavior in question. Finally, given a sufficient degree of actual control over the behavior, people are expected to carry out their intentions when the opportunity arises.

The three major determinants in the theory of planned behavior - attitudes toward the behavior, subjective norms, and perceptions of behavioral control - are traced to corresponding sets of accessible behavior-related beliefs. As noted, attitude toward the behavior is assumed to be determined by beliefs about the behavior's outcomes, each belief weighted by the subjective value of the outcome in question. A similar logic applies to the relation between normative beliefs and subjective norm, and the relation between control beliefs and perceived behavioral control. Normative beliefs are the perceived behavioral expectations of such important referent individuals or groups as the person^,s family, friends, and coworkers. These normative beliefs - in combination with the person's motivation to comply with the different referents - determine the prevailing subjective norm regarding the behavior. Finally, control beliefs are related to the perceived presence of factors that can facilitate or impede performance of the behavior. The perceived power of each control factor to impede or facilitate behavioral performance contributes to perceived control over the behavior in direct proportion to the person's subjective probability that the control factor is present.

We have seen that expectancy-value theory accounts for attitudes toward performance of a given behavior by directing attention to the behavior's perceived consequences. In addition, the theory has been extended to account for subjective norms and perceptions of behavioral control. As in the case of attitudes, formation of these factors is traced to readily accessible beliefs: normative beliefs in the case of subjective norms and control beliefs in the case of perceived behavioral control. As a result, the theory has done much to further our understanding of the factors that determine human social behavior.               

- IA