| Human beings are conditioned to believe that lying is | | | | analog polygraphs have traced out their |
| morally and biblically wrong. They do not like to lie but | | | | measurements on moving paper rolls which look |
| do so consciously or unconsciously when they are | | | | similar to fax paper rolls on early 90's fax machines. |
| under pressure. Lying produces nervousness and | | | | These papers are then annotated by the examiner |
| anxiety. These two conditions in turn produce distinct | | | | during the polygraph test and read after the |
| physiological effects that are sometimes visible and | | | | completion of the test. |
| most often measurable in a lie detection machine | | | | More recently, polygraph machines have been |
| such as a polygraph. The physiological effects of lying | | | | hooked up to and its measurements recorded onto |
| include: | | | | laptop or desktop computers thus making it easier |
| - An increase in breathing rate accompanied by a | | | | for the examiner to administer the test without |
| decrease in the depth of each breath, also known as | | | | having to fumble around with lengthy paper rolls. |
| shallow breathing. The pneumograph aspect of the | | | | Computers have revolutionized the way polygraphs |
| polygraph measures these effects. | | | | are recorded. Computers have made analog |
| - An increase in blood pressure and pulse rate. The | | | | polygraphs obsolete and make it efficient in storing |
| cardiograph aspect measures these vital signs. | | | | the results of multiple subjects in one place. |
| - An increase in sweating. The galvanograph aspect | | | | The most important aspect of digital polygraph |
| measures the difference in the electrical resistance of | | | | machines is the software program. The software |
| the skin as the subject sweats under pressure. | | | | program includes chart analysis capabilities designed to |
| Electrical conductivity increases with an increase in | | | | help the examiner in interpreting the results. |
| sweating due to the electrolyte concentration found | | | | Again, the results of digital polygraph tests can be |
| in perspiration. It does not measure the amount of | | | | inconclusive provided that the test subject has had |
| sweat directly. | | | | previous surgeries, illnesses, or is taking drugs, |
| The lie detector machine records the measurements | | | | medications, or alcohol. |
| on an analog graph. Over the last half century or so, | | | | |