This chapter is the first of three chapters dealing with personal and societal aspects of the AIDS epidemic. It begins with an introduction to individual decision making and action in which the general model for decision-making consists of four components: knowledge, attitude, intention, and behavior. It is pointed out the decision-making process is complex for HIV/AIDS because of the probabilistic nature of HIV risk information. This concept is expanded in the following sections, which discuss the factors that affect individuals’ assessment of information related to HIV transmission.
In a section on risk assessment, various examples are given to explain the nature of probabilistic information and its role in decision-making. For instance, the decision by one student on whether to have sexual contact with another knowing that on average one in two hundred students are infected with HIV is discussed. Two models of assessing probabilistic information are introduced. In the first model, the normative model, probabilistic information is weighted according to statistical rules to reach conclusions. This is the way scientists would use such information.
The second model, the subjective probability model, in contrast, is the way most other people process probabilistic information. In this context, the concept of judgement heuristics or rules of thumb is discussed in detail with specific examples of decision making used to illustrate the concept. Two aspects of representative heuristics are highlighted: first, that heuristic judgements are often made unconsciously; and second, that it is the perception of reality, not the actual reality, that determines how someone will decide on subjective probabilities. The important point is made that how much an individual’s perception of reality corresponds to the actual reality will depend on how much information the individual has. Consequently, one way to influence decision making is to provide more information through education.
It is explained that two other important factors in decision making are availability and anchoring. Availability of information in the memory is shown to be dependent on two main factors: familiarity and salience. These concepts are again illustrated by easily understood examples. For instance, the example of salience that is given is the increase in HIV testing that occurs when a celebrity such as Rock Hudson is diagnosed with AIDS, or, in the case of Magic Johnson, with HIV. Both these news events led to an increase in saliency about AIDS for many individuals that, in turn led to more people getting tested. The concept of anchoring is described as the idea of how our initial estimate or base affects our subsequent estimates. The example that is given is how the assignment of a random number can influence the answer to the estimate of the percentage of African countries in the United Nations. It is pointed out how these three judgement heuristics- representativeness, availability, and anchoring can lead to errors in estimating risk.
Finally, the theoretical section on risk assessment ends with a discussion of optimistic bias or personal invulnerability. Young people often underestimate the risk of their sexual behavior leading to HIV infection because of feelings of immortality that result from optimistic bias.
The chapter concludes with a section on HIV testing and risk assessment. The question is asked whether an HIV test will provide a definitive answer to HIV risk. The answer is analyzed in terms of the nature and the accuracy of the test and it is concluded that the HIV test per se does not tell us whether we are at risk for HIV. It is explained that only an understanding of the modes of HIV transmission and their relationship to our lifestyle will give us that information. This leads into a section of the importance of pre-test and post-test HIV counseling to present information about transmission modes and risk behaviors. HIV home tests are described, and an HIV home testing kit is shown in Figure 8-1. The concepts of confidential versus anonymous testing and their relative merits are then discussed.
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