“I don’t have anything to hide, and I am doing everything in my power to clear my name,” he said a few days ago.
According to him, he has not used EPO or blood transfusions. I really hope so. I think he is an interesting rider, and surely I hope that he has never used any kind of doping to become a better rider. But really, passing a polygraph test is quite simple. Tyler Hamilton for example claims that he beat the test. The results may be accurate in Kreuziger’s case, but to some people it looks like a desperate move in the final hours before the court hearing. The test result may not be accurate.
The idea of a polygraph is that telling a lie will give a stress reaction and that this reaction can be measured and identified. It normally consists of simultaneous measurement of three different bodily functions; heart rate, breath and palm sweating - the last being measured by electrical conductivity changes in the skin due to the moisture from perspiration.
The candidate for the test has to answer some questions. A couple of them should be answered with the true answers, others with a lie. In this way, the investigator seeks to establish the stress pattern of that individual person, using the measurements from the control questions to try to interpret the measurements during the interrogation by comparing it to the control-question responses. And this will purportedly tell whether the candidate is lying.
First of all - as described by its form of measurement - it doesn't measure lies, it measures emotional and physical stress. This means that the investigator has no idea exactly why the candidate responds to the question in matter. It could be largely anything. And this is reflected in the results. Proponents of the lie detector sometimes claim above 90% accuracy. But most hold it to be around 80% accurate, maybe 85 at best.
These above guessing percentages of 80% accuracy applies only if the candidates are not trying to fake their way through the test or does not know how to do so. There are many things affecting these physiological parameters. The faking methods can broadly be divided in to two types. 1: Making yourself startled by secretly pinching yourself or thinking of something frightening during the control questions. 2: controlling your response by mental techniques or slow breathing during the actual interrogation. Thinking of happy things or just being generally joyful and confident are known to really affect the results. Or you could take a substance altering your body’s stress response so that it is permanently heightened or lowered.
I do hope that Kreuziger has not done anything, but the lie detector test really does nothing to prove that he tells the truth. According to CAS, a hearing date has not yet been scheduled. So he still has to wait for the verdict. If believed to have cheated, he could face a a two- to four-year doping ban.