(NEXSTAR) — A recent polygraph test taken in Orange County, more specifically, on Bravo’s “The Real Housewives of Orange County,” has brought the validity of polygraphs — also called “lie detector tests” — into question. Even though some police departments and counterintelligence units use them, generally, results of such tests aren’t admissible in court.

So what does the research say?

Though polygraph-type machines have existed in some form since the late 1800s, the machines, which detect micro changes in a person’s bodily functions, came to popularity in the 1920s and ’30s, according to research out of Harvard’s Countway Library. Modern polygraphs record bodily changes like respiration, blood pressure and sweat gland activity, which many believe are said to reveal stress and/or deception.

But even though today’s polygraphs are more advanced, the science behind them has still yet to be proven effectively enough and the science community on the whole considers the practice pseudoscience.

Chief among the most frequently cited and well-regarded studies on polygraphs are multiple works by Dr. Leonard Saxe, who conducted much research on the topic through the 1980s and ’90s. Saxe’s 1983 study, “Scientific Validity of Polygraph Testing” found that while polygraphs can have some very limited practical uses, even these are very susceptible to failure.

Saxe has called the error rate for polygraph testing “significant,” and concluded that even studying polygraph testing is fallible because so many factors must go right for the tests to be conducted properly. Meanwhile, more recent research backs up Saxe’s findings.

The National Research Council published what Vox calls “an exhaustive report” on polygraphs in 2003 titled “The Polygraph and Lie Detection,” pointed out many similar issues with ever truly knowing whether or not polygraphs can detect the truth. A few reasons researchers pointed to:

• the physical responses that polygraphs measure don’t necessarily reflect deception. A person could merely be nervous about taking a test, feel pressured by the test administrator, suffer from anxiety or be affected by various medications and/or drugs
• Testing can be skewed to elicit specific results. For instance, an administrator could be asking specific/loaded questions to get a desired result. Alternatively, administrators can have biases toward certain individuals and/or situations, in addition to incorrectly believing that certain behaviors indicate deception
• Research testing can be consciously or subconsciously skewed to favor a certain result by test takers, meaning that even observing tests can be difficult and affect results

Another point that these two expansive research projects touch upon, as do others, is the possibility that stories of “confessions,” or else, anecdotal evidence of testers being caught in lies could merely have been brought upon by the pressure of taking a test. For instance, someone may not know that the science on polygraphs is flimsy, so they may think, “I might as well tell the truth since they’ll be able to tell anyway.” In other words, the test brought about the truth but it did not detect it.

Many researchers also point out that polygraph research is a subject of study that has not benefitted from technological advancements and time, which is unusual.

In 2002, the National Research Council of the National Academies of Sciences, Engineering and Medicine researched polygraphs at the behest of the U.S. Department of Energy, with the council ultimately recommending the Department should not use polygraphs because they aren’t reliable.

The council wrote: “Almost a century of research in scientific psychology and physiology provides little basis for the expectation that a polygraph test could have extremely high accuracy.”

Despite a failed polygraph test being considered a “smoking gun” on this season of “RHOC,” the science would appear to be on the side of “Real Housewife” Katie Ginnella, who was accused by castmates of spilling cast rumors and secrets to bloggers.