At the end of thread 16, there was discussion about the validity and admissibility of polygraphs in general. This is anecdotal, but here it goes: *many* years ago when I was in high school, we had career week where we had various groups, agencies come in. One day, it was law enforcement. One of the activities was to administer a polygraph to two students (who were selected by teachers, but more on that in a bit) at the afternoon assembly.
I was selected and met with the detective #1 in the morning. He asked me basic questions and then told me to lie about two details (my middle name and my age) and be truthful about the rest. When it came time for my polygraph, neither the detective who asked the questions (detective #2) nor the one who interpreted the results (detective #3), knew I was instructed to lie. I did very well. One question was flagged as suspect (one I answered truthfully). My lies didn't register. I'm certain it's because I was coached in advance, instructed to lie to illustrate a point and that there were no consequences to my lies.
The other student met with detective #1 in the morning. She was also given the list of questions but was instructed to answer truthfully. Later in the afternoon, she did poorly on the polygraph. It turns out detective #1 asked the teacher to recommend a student she (the teacher) knew to be uncomfortable in front of large groups and who didn't like public speaking. Nerves and anxiety undoubtedly were undoubtedly factors in her poor performance. Before feeling too badly for her, she was indicted to participate in order to extra credit points in her class. She was a good sport about it.
(Side note: no need for a polygraph for me. I have NO poker face.)
Now, I know this was an overly simplified experiment and the science and technology has changed significantly in the past few decades. Polygraphs can be useful *tools* and perhaps provide a direction in the investigation, but they're not infallible.
