The Polygraph and Lie Detection (2003) / Chapter Skim
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4 Evidence from Polygraph Research: Qualitative Assessment
4 Evidence from Polygraph Research: Qualitative Assessment
Pages 106-120
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From page 106... ...
We examined the broader literature because the empirical research on polygraph screening is too limited to support any judgments and because it is possible to gain useful insights about the potential value of polygraph screening from examining the evidence on polygraph test accuracy in specific-incident applications. This chapter provides a qualitative assessment of research on polygraph validity.
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From page 107... ...
analysis suggests that conclusions about the accuracy of the polygraph have not changed substantially since the earliest empirical assessments of this technique and that the prospects for improving accuracy have not brightened over many decades. We used several methods to gather as many polygraph validation studies for review as possible (see Appendix G)
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From page 108... ...
Field studies are most valuable when they involve controlled performance comparisons, where either the field system is experimentally manipulated according to the subtraction principle (see Chapter 3) or where observational data are collected systematically from
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From page 109... ...
EXPERIMENTAL FIELD STUDIES The most compelling type of field validation study is an experimental field study, one in which a variable of interest is manipulated among polygraph examinations given in a real-life polygraph testing context, for example, the context of an actual security screening program. The variable of greatest interest is usually guilt/innocence or deception/truthfulness on relevant questions, a variable that is difficult, though not impossible, to manipulate in a field setting.
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From page 110... ...
Good field research may require substantial funding, interagency cooperation, and enough time to resolve major logistical, ethical, interprofessional, and political problems, especially when experimental manipulation is intended. Nevertheless, so long as these obstacles are allowed to impede research, the scarcity of good field studies will remain a substantial impediment to appraising the scientific validity of the polygraph.
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From page 111... ...
In combination, these are powerful impediments to high-quality experimental field research on polygraph testing. However, polygraph testing leads to important, even life and death, decisions about the examiner, and it also affects families, associates, and national security; consequently, it is worth making an effort to use the best feasible research designs to evaluate it.
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From page 112... ...
As with clinical experimentation, issues once addressed only with qualitative methods, such as causal inference from observational data, are now the focus of competing quantitative mathematical models. In typologies of observational studies, the top rungs of a generally accepted quality hierarchy are occupied by studies that, despite the absence of experimental control, do incorporate controls for potential biases and for confounding by extraneous factors that most closely mimic those of designed experiments.
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From page 113... ...
This procedure probably yields an upward bias in the estimates of polygraph accuracy because the relationship between polygraph results and guilt is likely to be stronger in cases that led to confessions than in the entire population of cases. This bias can occur because definitive polygraph results can influence the likelihood of confession and the direction taken by criminal investigations (see Iacono, 1991, for a discussion; we offer a quantitative example below)
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From page 114... ...
Neither were data provided on the extent to which a suspect's polygraph results led an investigation to be redirected, leading to the determination of the truth. Both these outcomes of the polygraph examination are good for law enforcement, but they lead to overestimates of polygraph accuracy.
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From page 115... ...
In summary, we were unable to find any field experiments, field quasi-experiments, or prospective research-oriented data collection specifically designed to address polygraph validity and satisfying minimal standards of research quality. The field research that we reviewed used passive observational research designs of no more than moderate methodological strength, weakened by the admittedly difficult problem that truth could not be known in all cases and by the possible biases introduced by different approaches to dealing with this problem.
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From page 116... ...
· Actors or other mock subjects could be trained to be deceptive or nondeceptive, much as in laboratory mock crime experiments but more elaborately, and inserted sporadically for polygraph testing in field settings: for example, they could be presented to polygraph examiners as applicants for sensitive security positions. · Selected physiological responses of genuine polygraph subjects could be concealed from the examiner in favor of dummy tracings, for instance, of an alternate subject listening to the same questions in another room.
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From page 117... ...
· "Blind" scorers might be used to score sets of polygraph charts, including charts of confessed foreign espionage agents whose activities were uncovered by methods independent of the polygraph and charts of other randomly selected individuals who underwent examinations in the same polygraph programs but who are not now known to be spies. While the bias issue raised above in connection with criminal incident field studies is also of concern here, its importance would be diminished by restricting the analysis to agents uncovered without the polygraph, by random selection of the comparison group, and by appropriately narrow interpretation of the results.
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From page 118... ...
Accordingly, our analyses of research on countermeasures are based only on unclassified studies. These experiences leave us with unresolved concerns about whether federal agencies sponsoring polygraph research have acted in ways that suppress or conceal research results or that drive out researchers whose results might have questioned the validity of current polygraph practice.
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From page 119... ...
Studies that call the validity of polygraph testing into question, whether by failing to find accurate detection or by finding that accuracy is not robust across the range of situations in which polygraph tests are used, would fail to appear in literature searches. We have not investigated the various allegations, so we are not in a position to evaluate the extent to which the alleged activities may have biased the literature.
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From page 120... ...
Laboratory studies, though important for demonstrating principles, have serious inherent limitations for generalizing to realistic situations, including the fact that the consequences associated with being judged deceptive are almost never as serious as they are in real-world settings. Field studies of polygraph validity have used research designs of no more than moderate methodological strength and are further weakened by the difficulties of independently determining truth and the possible biases introduced by the ways the research has addressed this issue.
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