skip.webb wrote on Jan 15^th, 2008 at 2:18pm:

When one takes a hearing test, one is asked to press a button when a sound is first heard or hold the button down, releasing it when the sound goes away.  This is done at varying frequencies to determine hearing loss.  Such a test requires attention and concentration on the part of the examinee to be as accurate as possible.  If one wanted to defeat the efficacy of the test then one might "think of something else" rather than paying full attention.  I suppose that the hearing test should be scrapped as unscientific as it requires active mental participation and cooperation on the part of the person being tested. Vision tests require the examinee to report whether one degree of magnification is clearer than another until the optimal lens magnification is discovered. If the examinee fails to concentrate or decides to "think about something else" rather than follow the instructions given, he might walk of the examination wearing “coke bottle” lenses and tripping over his own feet.  Guess we should scrap that unscientific examination as well. ;) ;D

When one takes a polygraph test, what is supposedly being tested is the subject's answers with regards to truth or deception.

If the subject answers the questions truthfully it shouldn't matter what he or she thinks about afterward.

To continue with your comparison to the hearing test, if the subject heard the tone, pressed the button, and then thought about something else, how would they be interfering with the test?  They have already done their part.  That is far more similar to what is being discussed with a polygraph exam, since I am not suggesting that when asked a question the subject should refuse to answer and instead think of something else.

For the vision test, if a person correctly read the eye chart and then thought about something else, how would they be interfering with the test?  Your comparison suggests that the person does not read the eye chart (as in not answering the polygraph examiner's questions), which is not at all what was originally suggested.  However, it is, as I am sure you are aware, a nice straw man argument to add to the debate.