with the truth to the relevant questions. Thus, differen-
tial reactivity is expected from the innocent and the
guilty. Guilty subjects should produce consistently
greater physiological responses to the relevant ques-
tions than to the comparison questions, and innocent
subjects should produce consistently greater physio-
logical responses to the comparison questions than to
the relevant questions. If differential reactivity is not
observed—that is, no response to either question type
or equal response to both question types, the test is
considered to be inconclusive.
In application, a CQT will contain between two
and four relevant questions and a similar number of
comparison questions. The question series will also
contain some neutral and other questions that are not
used directly for credibility assessment. The questions
will be repeated a minimum of three times, but more
presentations may be obtained. The resultant data are
evaluated by making systematic comparisons between
the responses to relevant questions and contiguous
comparison questions. The standard in application is a
human-based system that is semi-objective in that it is
rule based, and in some physiological response sys-
tems, actual objective measures of physiological
response are made (e.g., the electrodermal response),
but in other response systems, human judgment is
involved in making evaluations (e.g., the respiratory
responses). Currently, there are three human-based
scoring systems in use in the field, and persons trained
in those systems show high levels of reliability in their
total scores. Reliability coefficients for total scores are
usually .9 or better.
Validity studies of the CQT have produced a range
of estimates. However, current meta-analyses seem
to be converging on a validity estimate for the CQT
of near 90% accuracy for decisions (i.e., excluding
approximately 8% of the tests that are inconclusive.)
That said, there is controversy in the literature con-
cerning the appropriate methodology for both labora-
tory and field studies in this area and about the
generalizability of currently obtained results. By
manipulating those studies that one views as having
adequate methodology, the estimate of the validity of
the CQT can be increased or decreased in reference to
the figure mentioned above.SSttrreennggtthhss ooff tthhee CCQQTT
The great strength of the CQT is its wide applica-
bility. The CQT is a highly versatile technique that can
be applied to most credibility assessment situations. Ifunambiguous relevant questions can be formulated,
then the applicability of the CQT would seem to be
limited only by the subject’s mental competence. In
the laboratory and in many field studies, the CQT has
been shown to be capable of a high level of accuracy.WWeeaakknneessss ooff tthhee CCQQTT
The CQT is criticized at a number of levels. At one
level, the CQT is criticized because it lacks a well-
developed theory of underlying processes to explain
why it works. Certainly, the lack of theory has ham-
pered basic research in this area. An articulated the-
ory would be useful in guiding research and in
predicting conditions of generalizability of research
results. However, the CQT polygraph is not unique in
being a technology in successful widespread applica-
tion without complete understanding of the underly-
ing processes. Aspirin was in widespread use as a
fever reducer and pain reliever for over 100 years
before a complete explanation of its mechanisms was
forthcoming.
A more telling criticism of the application of the
CQT, particularly in the United States, concerns a lack
of professional standards and regulation. Polygraph
testing in the United States is controlled by a patch-
work of standards and state licensing regulations. In
many states, there is no regulation at all. As a result,
the quality of practice in the polygraph profession in
the United States is highly variable. Worldwide, this
may not be the case. In Israel and Japan, psychologists
are heavily involved in polygraph programs. In the
People’s Republic of China, the government polygraph
program is organized within the Chinese National
Academy of Sciences. One positive development con-
cerning standards is that the American Association of
Testing and Materials International (ASTM) has
recently formed committees and is promulgating con-
sensus standards for the administration of polygraph
tests and for the training of polygraph examiners.
It has been suggested that some police agencies in
the United States use the polygraph primarily as an
interrogation prop to aid in obtaining confessions.
Anecdotally, there are several well-known exonera-
tion cases that have involved polygraph examinations
as part of the process leading to false confessions.
This is a topic clearly in need of additional research.
Finally, the CQT shares with the CKT a similar
weakness regarding countermeasures. Some knowl-
edgeable subjects can use mental and physical coun-
termeasures to produce false-negative outcomes inPolygraph and Polygraph Techniques——— 599P-Cutler (Encyc)-45463.qxd 11/18/2007 12:43 PM Page 599