Your Apple Watch or Fitbit may not be measuring your steps or heart rate accurately if you are a person of color.
Lots of people wear smartwatches and fitness trackers — nearly 40 million in the U.S alone. These fitness trackers not only measure steps, but also use sophisticated laser technology to monitor heart rate and other physiological measures of well-being. But the technology that manufacturers rely on was designed effectively with light-skinned people in mind, and according to researchers and reporters, is likely to provide erroneous readings for people with darker skin.
No wonder all that walking wasn’t making me lose weight.
Let’s take Fitbit for example, which uses the industry-standard laser technology in its trackers. If you own one, you’ve probably seen the green lights peeking out from beneath the device when you take it off. These lights rest against the top of your wrist and are used to measure heart rate. In between heartbeats the volume of blood in your blood vessels declines. If a light is shined onto your skin, it reflects back in differing amounts depending on how full of blood your vessels are at the moment. The cadence of darkening and lightening blood vessels changes as a result of your heart rate, and this cadence is what the green lights in your Fitbit measure. They then convert this cadence into a relatively accurate measurement of your actual heart rate.
However, darker skin has more melanin pigment, which has been conclusively proven to block green light, making it much harder to get an accurate reading. The darker your skin, the less accurate the reading.
Research on the issue is still ongoing, but one of the few papers on the topic noted that not only were there connections between inaccurate readings for dark skin, but also for differing skin types. Anecdotal evidence for this phenomon is also easy to find: lots of consumers have complained about inaccurate readings over the years. Little has been done to solve the problem so far.
Why Does This Matter?
Unconscious bias in technology is not a new problem. Though new technologies appear objective, implicit biases often leak into how they are researched, designed and marketed to a diverse public. There is substantial unconscious bias in other areas of design (just ask women about the freezing temperatures in older office buildings which were traditionally designed for men) so its discomforting but unsurprising to find the problem crop up in the world of health and fitness wearables.
The real impact of these biases is felt in the secondary effects the wearable market is having on important scientific research — which often relies on these devices to make important measurements in studies. Health insurance companies and employers often offer lucrative bonuses or discounts to employees who meet certain step or heart rate metrics on their fitness trackers. Individuals of color could be missing out on a number of these benefits without even knowing it.
What Can Be Done?
Fitbit is apparently aware of this issue and has tried to boost the power of the green light in its trackers to account for skin color. Apple has added an infrared light to its Apple Watch to supplement readings from its bank of green lights. But for now, these efforts may be ineffective stopgaps. Green lasers are used by all of the major brands to measure heart rate because they are cheaper to produce and less prone to erreonous readings due to movement — a must-have in a device that literally measures movement.
Its good that these companies are slowly becoming aware of the issue their devices pose for people of color. At the same time, its also important for researchers, sports medicine doctors, insurance companies, employers and the general public to know how inaccurate wearables can be for darker-skinned people. Awarness is the first step toward conscious design.
Tools must be consciously designed with forethought and inclusivity in mind, not only because its the right thing to do, but also because it makes business sense … especially when nearly half of the consumers who purchase these products in the U.S. are people of color.