Selling snake oil is all about marketing, which means that a good snake oil product needs to have a great angle or a hook. Popular snake oil hooks include being “natural,” the product of ancient wisdom, or “holistic.”

Perhaps my favorite snake oil marketing ploy, however, is claiming the product represents the latest cutting-edge technology. This invariably leads to humorous sciencey technobabble. There are also recurrent themes to this technobabble, which often involve “energy,” vibrations and frequencies, or scientific concepts poorly understood by the public, such as magnetism and (of course) quantum effects. Historically, even radioactivity was marketed as a cure-all.

One category of technical pseudoscientific snake oil measures some physiological property of the body and then claims that this measurement can be used for diagnosis and determining optimal treatment. For example, machines might measure brain waves, heart rate variability, thermal energy or (the subject of today’s article) the galvanic skin response.

These are all noisy systems – they are highly variable and produce a lot of random results that can be used to give the impression that something meaningful is being measured. Systems that rely on these measurements to make highly specific determinations are no different than phrenology or reading tea leaves, but they look scientific.

The galvanic skin response

I was recently asked to look into a product called Zyto technology. This is an electronic device that you place your palm on top of so that it can read your “galvanic skin response” (GSR) to specific stimuli. It then uses your responses to prescribe a specific treatment.

The GSR is actually an older term for what is now called electrodermal activity (EDA), which is simply the electrical conductance of your skin (Harriet Hall has written about such devices before). Skin conductance is primarily affected by sweat, as salty water is an excellent conductor. So essentially the machine is measuring how sweaty your palms are.

Sweatiness, in turn, can be affected by a number of variables, one of which is your current level of psychological “arousal.” Arousal is a deliberately non-specific term, because many types of arousal can increase your autonomic activity which causes sweating. Arousal can be anger, fear, anxiety, being startled, excited, or under mental stress. You cannot tell which simply by measuring EDA.

The EDA is one measure that is used in the polygraph test, which is famously unreliable precisely because you cannot infer the source of the stress that is being measured. Is it due to the stress of lying, or the stress of being interrogated?

Environmental conditions, such as ambient temperature, can also affect the autonomic response.

There is also a great deal of individual variability. Different people have very different levels of autonomic activity in response to different stimuli. These highly variable responses can then further vary based upon mood, environment, medication, and underlying conditions.

Such a noisy and highly variable system is problematic for measuring a specific property (such as stress) although it can be of some use in highly controlled situations, such as rigorous scientific studies. The only real clinical application of measuring EDA is for measuring autonomic function itself (in order to diagnose an autonomic disorder). Otherwise it is simply too variable to be of much clinical use.

This variability, however, makes it perfect as a target for pseudoscience.

Zyto Technology

I always love reading that part of a snake oil website that is labeled, “how it works.” In this case the Zyto website has a detailed description. They begin:

ZYTO Scan technology uses Virtual Stimulus Items, or VSIs, which are computer-generated digital signatures that represent specific physical stimuli.

The nonsense begins right up front. They are claiming that they have somehow divined the “digital signatures” of specific toxins, foods, and nutritional supplements. I would love to see the study that established the specific “digital signature” of Gingko biloba.

There is, of course, no basic scientific principle by which you could determine the specific type of electrical stimulation that represents bananas, for example. The very idea is not scientific. If these signatures were determined empirically, imagine how much work that would take. Where are the thousands of studies necessary to create these “VSIs?”

They further claim that:

The body is able to respond to the virtual stimulus in less than one second.

This is demonstrably wrong – EDA requires a few seconds on average. There is nothing they could do to get the body’s autonomic response to be quicker than it is.

After the Zyto hand cradle measures the EDA in response to their virtual stimulus:

The ZYTO software analyzes the data for patterns of coherence. Coherence is a state where two or more things exist without conflict. By tracking the body’s Galvanic Skin Responses, ZYTO technology can calculate shifts in coherence to VSIs. In other words, the shift patterns indicate whether VSIs exist in coherence or conflict with the body.

The concept of coherence or conflict of the EDA (or GSR as they call it) is utter nonsense with no basis in established science. This is the pure magical thinking that ultimately lies at the heart of such devices. This is the “phrenology” component. The device assigns either a positive or negative result to each stimulus then compiles the results.

The ZYTO software then creates a detailed report that translates the analyzed data and your biological preferences in an easy-to-read graphical interface. Essentially, the report presents the body’s responses ranked in order of priority, which can then be used to facilitate better decision making about your health and wellness.


Zyto: Carefully not giving you medical advice (or useful information)

They are careful not to prescribe a specific treatment, just to inform your health decisions. The user gets a result like the picture above. I could determine if you require calcium and magnesium supplements much more accurately by simply measuring the calcium and magnesium levels in your blood, but I guess that’s too old-school.

This is a remarkable chain of claims made for Zyto technology. In order to be true then there would have to be virtual digital signatures for things like food and toxins, the EDA would have to be somehow quicker with their device than normal physiology, and there would need to be some physiological basis for “coherence and conflict” in the EDA which is currently completely unknown to science

Further, think of how extensively each device would need to be calibrated in order for any results to be meaningful. The EDA varies from person to person, with environment, and with current mood. Extensive calibration and standardization would be necessary for the results to be anything other than pure noise. Even the manner in which a user places their hand on the device could affect the results.

In fact, they admit on their website:

Because ZYTO technology interfaces with the body’s fastest moving component, energy, biosurveys can collect a significant amount of information in a short amount of time. Since energy moves and fluctuates so quickly, you are likely to see differences if you repeat a biosurvey and compare individual data points.

In other words – there is no reliability to the results, by their own admission. They make no further comment about this. I guess they think by admitting this, users will expect the variability and not worry about it.

Just to add one more layer of pseudoscience, the write:

Although no meridian points are directly measured, many Virtual Stimulus Items in the software that represent meridians, individual acupuncture points, and even EAV points (Electro-Acupuncture according to Voll) can be measured.

Conclusion: Zyto is Sciencey and pseudoscientific, not science

Measuring GSR or EDA in order to infer some biological property or state is highly problematic, even for careful and rigorous researchers. It is, however, the perfect target for snake oil pseudoscience.

Measuring EDA gives the impression of advanced technology and of measuring something real, at least to the uninformed. It is also a set up for confirmation bias and other cognitive biases that are likely to convince the user that it is working.

For the non-expert who is confronted with similar claims, it is helpful to recognize the red flags. It is highly unlikely that any one approach to diagnosis could provide such a wide variety of specific information. Also, think about all the specific information that would be necessary for such a device to work. Finally, you can ask yourself if the technology is being used by mainstream physicians and at universities. If not, then why not?

When it doubt, of course, you can always search Science-Based Medicine.



Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the president and co-founder of the New England Skeptical Society, the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also contributes every Sunday to The Rogues Gallery, the official blog of the SGU.