Home Page > Reading Room
The following is a statement on the evidentiary value of polygraphy made available by former FBI supervisory special agent and scientist Dr. Drew C. Richardson (1951-2016). In January 2003 it was used by a defendant in an administrative hearing to successfully discredit (along with other non-polygraph evidence) polygraph exam results obtained/performed by a well-known polygrapher (a former head of a federal agency polygraph unit).



Mr.      :

My name is Dr. Drew C. Richardson. The following is a written statement that I have prepared in connection with an administrative matter involving Mr.      . That which follows is my evaluation and opinion of probable-lie control question test (CQT) polygraphy, a group of polygraph exam formats widely known by the general public as the so-called "lie detector" test and which are commonly used as such in this country and around the world. I believe the aforementioned methodology has little to no value as a diagnostic instrument for determining truth and falsehood related to matters under investigation. I believe this to be the case for a variety of reasons to be subsequently discussed. Recent surveys of the members of the Society for Psychophysiological Research and the Fellows of the American Psychological Association's Division I (General Psychology) would indicate that my previously stated general opinion regarding CQT polygraph testing is shared by a large majority of scientists with relevant scientific backgrounds.

In order to explain why the CQT polygraph test is theoretically flawed (and recognized as such by the relevant scientific community), I need to explain the fundamentals of its operation and associated assumptions of practice. Essentially an examinee is asked two types of questions whose physiological responses produced in response to their asking are scored and inter-compared. These two types of questions are relevant and control questions. If a bank robbery is being investigated, a typical relevant question would be "Did you rob the bank?" and a typical control question would be "Prior to the age of 18, did you ever steal something from someone who trusted you?" If on average, the polygraph examinee is found to have greater responses to relevant questions, he/she is found to be deceptive and is found to be non-deceptive, if again, on average, the responses are greater for control questions. The prevailing polygraph theory for how and why a polygraph exam would be expected to work (successfully) is "fear of detection," i.e., a guilty examinee will be more concerned about being detected in a lie to relevant questions and an innocent examinee will be more concerned about his truthfulness to control questions.

The reason I believe the above theoretical explanation is badly flawed and is particularly likely to be harmful (i.e., leading to a wrongful determination of deception) to an innocent examinee telling the truth about matters being investigated is what I have previously and publicly referred to as "fear of consequences." I believe that it is quite plausible and probable that an innocent examinee will respond to the consequences of being labeled a liar, rather than fear of detection of being caught in a lie. These consequences could include (in a criminal matter) further investigation, prosecution, conviction, imprisonment, loss of family, friends, money, reputation, etc. In an administrative (academic) setting an inquiry subsequent to a false positive polygraph result might include loss of income, reputation, and general embarrassment amongst many possible consequences and outcomes. Again this has absolutely nothing to do with lying, but with an innocent examinee being concerned about the consequences of being branded a liar. This is perfectly consistent with the autonomic nervous system (ANS) physiology being measured by a polygraph examiner and a variable which cannot be reasonably controlled for by that examiner.

In addition to the aforementioned consideration that I have raised, an examinee might well react to a given relevant question due to surprise (if a question was not properly reviewed with the examinee), anger, due to revulsion (e.g. the notion of child sexual abuse), noise, movement, pain (caused at various random points due to cardio cuff pressure), variations in the voice inflection of the examiner as well as a host of other operator error that might occur with any given examiner. For all of these reasons (particularly the flaws in basic theory and a lack of scientific control), I again conclude that CQT polygraphy has very little diagnostic value in determining truth regarding matters under investigation and that results of these "tests" should NOT serve as a basis for any subsequent action involving said matters under investigation.

                    Sincerely yours,

                    Drew C. Richardson, Ph.D. Home Page > Reading Room