At Quantified Self meetings we’ve heard from people who track their habitual tardiness, or the amount of coffee they drink, their alertness, or the number of times they sneeze. I can honestly say that anything that can be tracked is being tracked by someone somewhere. At a recent international Quantified Self conference, I made this challenge: Let’s think of the most unlikely metric we can come up with and see if someone is tracking it. So I asked a group of 500 self-trackers: Is anyone tracking their fingernail growth? That seemed pretty absurd. One person raised their hand.
Shrinking chips, stronger batteries, and cloud connectivity has encouraged some self-trackers to attempt very long-term tracking. Particularly of one’s health. Most people are lucky to see a doctor once a year to get some aspect of their health measured. But instead of once a year, imagine that every day, all day, invisible sensors measured and recorded your heart rate, blood pressure, temperature, glucose, blood serum, sleep patterns, body fat, activity levels, mood, EKG brain functions, and so on. You would have hundreds of thousands of data points for each of these traits. You would have evidence while at both rest and at full stress, while sick and healthy, in all seasons, all conditions. Over the years you would gain a very accurate measurement of your normal—the narrow range your levels meander in. It turns out that, in medicine, normal is a fictional average. Your normal is not my normal and vice versa. The average normal is not very useful to you specifically. But with long-term self-tracking, you’d arrive at a very personal baseline—your normal—which becomes invaluable when you are not feeling well, or when you want to experiment.
The achievable dream in the near future is to use this very personal database of your body’s record (including your full sequence of genes) to construct personal treatments and personalized medicines. Science would use your life’s log to generate treatments specifically for you. For instance, a smart personalized pill-making machine in your home (described in Chapter 7) would compound medicines in the exact proportions for your current bodily need. If the treatment in the morning eased the symptoms, the dosage in the evening would be adjusted by the system.
The standard way of doing medical research today is to run experiments on as many subjects as one possibly can. The higher the number (N) of subjects, the better. An N of 100,000 random people would be the most accurate way to extrapolate results to the entire population of the country because the inevitable oddballs within the test population would average out and disappear from the results. In fact, the majority of medical trials are conducted with 500 or fewer participants for economic reasons. But a scientific study where N=500, if done with care, can be good enough for an FDA drug approval.
A quantified-self experiment, on the other hand, is just N=1. The subject is yourself. At first it may seem that an N=1 experiment is not scientifically valid, but it turns out that it is extremely valid to you. In many ways it is the ideal experiment because you are testing the variable X against the very particular subject that is your body and mind at one point in time. Who cares whether the treatment works on anyone else? What you want to know is, How does it affect me? An N=1 provides that laser-focused result.
The problem with an N=1 experiment (which was once standard procedure for all medicine before the age of science) is not that the results aren’t useful (they are), but that it is very easy to fool yourself. We all have hunches and expectations about our bodies, or about things we eat, or ideas of how the world works (such as the theory of vapors, or vibrations, or germs), that can seriously blind us to what is really happening. We suspect malaria is due to bad air, so we move to higher ground, and that helps, a little. We suspect gluten is giving us bloat, and so we tend to find evidence in our lives that it is the culprit and then we ignore contrary evidence that it doesn’t matter. We are particularly susceptible to bias when we are hurting or desperate. An N=1 experiment can work only if we can separate the ordinary expectations of the experimenter from those of the subject, but since one person plays both roles, this is extremely hard. This kind of inbred prejudice is exactly what large randomized double-blind trials were invented to overcome. The subject is unaware of the parameters of the test and therefore cannot be biased. What helps overcome some of our self-fooling in an N=1 experiment in the new era of self-tracking is automatic instrumentation (having a sensor make the measurement many times for long periods so it is “forgotten” by the subject) and being able to track many variables at once to distract the subject, and then using statistical means later to try to unravel any patterns.
We know from many classic large population studies that often the medicine we take works because we believe it will work. This is otherwise known as the placebo effect. These quantified-self tricks don’t fully counter the placebo effect; rather they work with it. If the intervention is producing a measurable improvement in you, then it works. Whether this measurable improvement is caused by the placebo effect doesn’t matter since we only care what effect it has on this N=1 subject. Thus a placebo effect can be positive.
In formal studies, you need a control group to offset your bias toward positive results. So in lieu of a control group in an N=1 study, a quantified-self experimenter uses his or her own baseline. If you track yourself long enough, with a wide variety of metrics, then you can establish your behavior outside (or before) the experiment, which effectively functions as the control for comparison.
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All this talk about numbers hides an important fact about humans: We have lousy mathematical intuitions. Our brains don’t do statistics well. Math is not our natural language. Even extremely visual plots and numerical graphs demand superconcentration. In the long term, the quantification in the quantified self will become invisible. Self-tracking will go far beyond numbers.
Let me give you an example. In 2004, Udo Wachter, an IT manager in Germany, took the guts of a small digital compass and soldered it into a leather belt. He added 13 miniature piezoelectric vibrators, like the ones that vibrate your smartphone, and buried them along the length of the belt. Finally he hacked the electronic compass so that instead of displaying north on a circular screen, it vibrated different parts of the belt when it was clasped into a circle. The section of the circle “facing” north would always vibrate. When Udo put the belt on, he could feel northness on his waist. Within a week of always wearing the north belt, Udo had an unerring sensation of “north.” It was unconscious. He could point in the direction without thinking. He just knew. After several weeks he acquired an additional heightened sense of location, of where he was in a city, as if he could feel a map. Here the quantification from digital tracking was subsumed into a wholly new bodily sensation. In the long term this is the destiny of many of the constant streams of data flowing from our bodily sensors. They won’t be numbers; they will be new senses.
These new synthetic senses are more than entertaining. Our natural senses evolved over millions of years to ensure that we survived in a world of scarcity. The threat of not having enough calories, salt, or fat was relentless. As Malthus and Darwin showed, every biological population expands right to the limit of its starvation. Today, in a world made abundant by technology, the threat to survival is due to an excess of good stuff. Too much goodness throws our metabolism and psychology out of kilter. But our bodies can’t register these new imbalances very well. We didn’t evolve to sense our blood pressure or glucose levels. But our technology can. For instance, a new self-tracking device, the Scout from Scanadu, is the size of an old-timey stopwatch. By touching it to your forehead, it will measure your blood pressure, variable heart rate, heart performance (ECG), oxygen level, temperature, and skin conductance all in a single instant. Someday it will also measure your glucose levels. More than one startup in Silicon Valley is developing a noninvasive, prickless blood monitor to analyze your blood factors daily. You’ll eventually wear these. By taking this information and feeding it back not in numbers but in a form we can feel, such as a vibration on our wrist or a squeeze on our hip, the device will equip us with a new sense about our bodies that we didn’t evolve but desperately need.