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The Polygraph and Lie Detection
causing physiological responses to those questions, regardless of the examinee’s truthfulness. It is also possible for an examiner’s expectancy to influence the way questions are selected, explained, or asked, to the extent that the test format is not standardized (Honts and Perry, 1992; Abrams, 1999). Basic research shows that expectancies can affect responses even when the responder does not know which responses are expected (e.g., Rosenthal and Fode, 1963). Consequently, examiner expectancies might influence responses even among innocent examinees on concealed information tests.
In employee screening, examiners may have expectancies not only about the truthfulness of individual examinees, but also about the base rates of true positives and true negatives in the population tested. In the DOE security screening program, for example, examiners reasonably believe that the likelihood of any individual examinee being a spy is very low. Their interactions with examinees might therefore be relatively low-key and unlikely to generate differential responses to relevant questions.
In both event-specific and screening applications, it is also quite plausible that examinees may vary in their expectancies about how the test will be used or about the particular examiner’s attitudes about them. Such responses, especially when specific to individuals, are very difficult to assess and take into account in interpreting polygraph charts.
It is easy to infer hypotheses from basic research in social psychology about the ways expectancies might affect polygraph test results. For example, examiners who have high expectancies of deceptive individuals among those they test may act in ways that elicit strong physiological responsiveness to relevant questions in their examinees, resulting in a high rate of false positives (lower specificity). Similarly, examiners with high expectancies of truthfulness might elicit weaker physiological responses, resulting in a high rate of false negatives (lower sensitivity). Or examiners who think an examinee is probably guilty can be hypothesized to elicit stronger emotional responses from the examinee than they would from the same examinee if they believed the person to be innocent. Expectancy research, as well as related research on behavioral confirmation (Snyder, Tanke, and Berscheid, 1977; Snyder, 1992; Snyder and Haugen, 1994), makes such hypotheses plausible, and polygraph theory provides no reasons to discount them as unreasonable. It therefore remains an empirical question whether polygraph test results and interpretations support such hypotheses and whether, in fact, test validity is diminished to any significant degree by examiner or examinee expectancies. (We discuss the limited empirical research on this question in Chapter 5.)
An important and somewhat special case of expectancies with great relevance to polygraph testing involves examinees’ expectancies regarding the validity of the polygraph test itself. Indeed, much of the utility