MedHum Monday Presents: The Mackenzie Ink Polygraph

DailyDose_PosterWelcome back to the Daily Dose and MedHum Mondays!

Imagine the scene: a man sits at a table attached to a machine that monitors his body. A question is asked–his brow sweats–his heart races–he lies! And the machine knows! The earliest of the polygraph tests developed out of research in cardiovascular health (just one more way studies of medicine made important changes in other fields). Today’s post is penned by Jared Larson, a student at Case Western Reserve University. Welcome to the history (and ethical considerations) of the polygraph!


The Mackenzie Ink Polygraph

Cardiology has long been a central aspect of medicine because of the heart’s crucial role in driving and regulating the most fundamental processes of the body. The slightest change in the functioning of the cardiovascular system can drastically alter an individual’s condition, making it essential for physicians to be able to understand and monitor heart activity. In order to obtain this information, devices were created to provide quantitative data regarding the state of the cardiovascular system, such as heart and respiration rate. One device, Sir James Mackenzie’s ink polygraph, was created to further understand the behavior of the heart through the observation of heart rate (“Mackenzie Ink Polygraph, 1906” 2013). This polygraph allowed physicians to identify abnormal heart activity in seemingly healthy individuals as well as recognize a connection between psychological and physiological responses, ultimately leading to the development of lie detection technology (2013). While the development of the ink polygraph was able to advance medicine in the early 1900’s, its modern counterpart is being criticized for its validity as a means of scientific evidence and potentially causing wrongful convictions of individuals in criminal proceedings.

Mackenzie’s device greatly influenced the practice of medicine by revealing how little was known about cardiovascular health in the early 20th century. The polygraph has two “tambours” that attach at the patient’s neck and wrist to obtain both a carotid and radial arterial pulse that then signals the ink stylus to record the data (2013). As a heart surgeon himself, Mackenzie initially tested his polygraph by using it to monitor his patients as he was operating (Krikler 1). After extending the use of his device to his regular patients, Mackenzie began to realize pulse irregularities in individuals he believed to be in perfect health (1). Mackenzie then began to use his ink polygraph to further assess his patients and understand the underlying causes of their irregularities (1). As a result, he was able to distinguish harmful heart murmurs from normal heart activity with the use of his polygraph and began to share the importance of monitoring heart rate as a means of understanding a patient’s condition (1). Mackenzie’s ink polygraph allowed him to contribute greatly to the development of the field of cardiology in the early 20th century by helping him understand an aspect of physiology crucial to his patients’ health; however, his invention’s ability to identify the smallest change in heart activity made it suitable for nonmedical applications as well.

Mackenzie’s device contained all the essential elements to operate as a lie detector, an invaluable tool of investigation still in use. By detecting an increased heart or respiration rate caused by a minute stress response, Mackenzie’s ink polygraph and subsequent models could identify when an individual was lying. Additionally, using a polygraph “assumes that telling a lie causes specific and reproducible physiologic responses related to the arousal of the autonomic nervous system and that an experienced examiner can elicit these responses routinely” (Steinbrook 1). This stress response of the nervous system influences the physiology of an individual, causing an increase in irregular heart activity as well as an increase in the overall heart rate. The polygraph then identifies and records this response, and a trained individual can recognize the specific pattern caused by a false statement (1). This method of lie detection is a powerful tool that has been applied to the criminal justice system in an attempt to identify guilty individuals in certain situations. Initially, the polygraph was believed to have a successful detection rate over 90%, providing an incredibly precise level of detection (Palvidis and Levine 1). Though Mackenzie’s ink polygraph may have contributed immensely to the field of cardiology and paved the way for further advances in forensic science, it may have had adverse effects in the courtroom.

Because the polygraph was seen as an almost infallible device capable of producing valid scientific evidence in criminal cases, it held great weight in the courtroom, helping determine the guilt of potential suspects. However, the use of the polygraph as a means of valid scientific evidence has become a controversial topic with reports of wrongful convictions based on false polygraph results. The false results can be caused simply by the stress of being tested with a polygraph; in fact, the same response “may also be caused by a myriad of potentially confounding factors ranging from stress, fear, and anxiety to anger and embarrassment” (Steinbrook 1). This kind of mistake can be presented as scientific evidence in a courtroom and can ultimately result in an individual being wrongfully accused and convicted. Further criticism of the instrument as a accurate has led to a movement against the use of the polygraph as a reliable means of obtaining evidence in court proceedings. Though the polygraph does have an incredible ability to help find the truth and an amazing rate of success, it’s lack of complete accuracy has detrimental effects on the fairness of the court system.

Though Mackenzie’s ink polygraph may be an extremely powerful tool able to provide insight into the cardiac health of a patient, its creation has also played a much more controversial role as a valid means of scientific evidence in the courtroom. With revolutionary inventions and discoveries like the ink polygraph becoming more prevalent in many important aspects of society, it is necessary to continue to question the knowledge obtained by such achievements to ensure that they do not have adverse effects that might outweigh the benefits of their use. Ultimately, the knowledge obtainable because of devices like the polygraph can provide amazing insight, but their abilities can also be detrimental to society.

Works Cited

Inbau, Fred E. “The First Polygraph.” Journal of Criminal Law and Criminology 43.5 (1953): 2-4. Web. 7 Feb. 2015.

Krikler, D. M., MD. “Profiles in Cardiology: Sir James Mackenzie.” Journal of Clinical Cardiology 11 (1988): 193-94. Wiley Online Library. Web. 7 Feb. 2015.

“Mackenzie Ink Polygraph, 1906.” Dittrick Museum of Medical History 11000 Euclid Avenue Cleveland, OH 44106 United States. 2013. Plaque.

Steinbrook, Robert. “The Polygraph Test – A Flawed Diagnostic Method.” New England Journal of Medicine 327.2 (1992): 122-23. Web. Feb. 2015.

Pavlidis, I., and J. Levine. “Monitoring of Periorbital Blood Flow Rate through Thermal Image Analysis and Its Application to Polygraph Testing.” IEEE Xplore. Engineering in Medicine and Biology Society, 2001. Web. 07 Feb. 2015.

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