Can You Cheat a Polygraph Test?
In the UK, it’s estimated that one in ten individuals attempts to cheat during a polygraph test. Whether through deliberate countermeasures or misinformation, these efforts are quickly identified by experienced examiners. Polygraph examiners are trained to recognize even subtle attempts to manipulate the results, relying not only on the technology but also on years of expertise observing human behavior. During the pre-test interview, we often address common tactics, debunk myths, and explain just how easily such efforts can be detected.
While the allure of “beating the test” may seem tempting for some, the reality is that polygraph tests are far more complex and nuanced than many people assume. The test measures multiple physiological responses across different systems in the body, such as heart rate, breathing, and sweat gland activity. Trying to manipulate one aspect while maintaining control of the others is nearly impossible without giving yourself away.
Common Polygraph Countermeasures
Here are some of the most common ways individuals attempt to manipulate polygraph results—and why these efforts ultimately fail:
1. Breathing Manipulation
Controlling breathing patterns is one of the most well-known but ineffective tricks. People often try to time their breaths unnaturally or exaggerate inhaling and exhaling, believing this will fool the machine. However, such behavior is incredibly easy for polygraph examiners to spot. Examiners are trained to notice irregularities, such as overly shallow or forced breathing, which stand out immediately during testing.
In fact, this tactic often backfires. Attempting to manipulate breathing can cause physiological stress, leading to heightened heart rates and other indicators that draw even more attention to deceptive behavior. Ironically, many individuals persist with this strategy even after being told that their irregular breathing has been detected. The result? Most fail the test spectacularly.
2. Blood Pressure Manipulation
Another common tactic involves attempting to manipulate blood pressure readings. Some individuals tense their muscles, adjust their posture, or clench their fists to interfere with the test results. These efforts are as ineffective as they are obvious. Purposeful tension creates spikes in readings that are easy for examiners to identify—especially when they occur consistently during specific questions.
When confronted, many claim they were “relaxed,” but trained examiners can easily distinguish between genuine nervousness and deliberate attempts to deceive. If such behavior continues, the test may be paused or stopped entirely, as cooperation is critical for a valid result.
3. Drug Use
Using drugs to suppress physiological responses is an extreme yet highly ineffective countermeasure. Sedatives, beta-blockers, or other substances designed to calm the body may reduce visible signs of stress but often result in overly flat, unresponsive test charts. This is a significant red flag for examiners.
In these situations, examiners use control questions and compare baseline responses to determine whether the individual is attempting to influence the test. If physiological responses are too subdued or absent, the test cannot proceed. Producing a flat chart is not considered “passing” the test—it simply means the results are invalid.
Intentional or Accidental Non-Cooperation?
It’s easy to assume that every irregularity or false response is a deliberate attempt to cheat. However, not all issues during a polygraph test are intentional. Innocent individuals sometimes cause disruptions unintentionally, mimicking countermeasure tactics without realizing it.
For instance, physical conditions like an unusually high resting heart rate or external factors such as excessive caffeine consumption can interfere with test accuracy. One recent case involved a subject with a resting heart rate of 140 beats per minute, which made it difficult to establish a baseline. After some questioning, we discovered they had consumed four cups of coffee before the test—an everyday habit for them but an unexpected complication for us. The test had to be rescheduled because their physiological responses were too erratic to proceed.
This is why thorough pre-test interviews are vital. During these interviews, examiners explain the process and discuss behaviors or external factors that might affect the results. Whether caused by misunderstanding or intentional deception, any behavior that hinders the process will result in the test being paused or stopped until proper conditions are met.
Can You Really Cheat a Polygraph Test?
We’re often asked if it’s truly possible to beat a polygraph test. The answer? Technically, yes—but only in ways that are blatantly obvious to a trained examiner.
Polygraph tests are far more sophisticated than the outdated lie detectors portrayed on TV or in movies. Modern techniques involve advanced equipment and extensive examiner training, ensuring that attempts to manipulate results are swiftly recognized. While some individuals may successfully disrupt a test enough to invalidate it, this is not the same as “cheating” or passing.
There’s also a persistent myth that paying more for a polygraph test guarantees better results. In reality, the accuracy and reliability of the test depend on the skill and ethics of the examiner, not the price tag. A qualified examiner will uncover the truth, regardless of how much the test costs.
In the end, the only foolproof way to pass a polygraph test is simple: tell the truth. Polygraph tests are designed to detect stress responses linked to deception. When you’re honest, there’s no reason for these stress indicators to appear, and the test will reflect that.
So, while you may feel nervous about taking a polygraph test, remember that it’s not there to trick you—it’s there to uncover the truth.