10 Physics Reasons Why Screens Are Bad for Humans

In the first article of this new column, dubbed 3T, William Softky looks at why staring at screens is bad for humans.
Screen addiction, addicted to screen, computer vision syndrome, shortsightedness, computer usage, technology, science, William Softky, technology news, news on tech

© Marcos Mesa Sam Wordley

Here are 10 interlocking reasons why using screens damages the human nervous system. The reasons are derived from basic mathematical principles of how matter and energy move in space and time. The gist is that the human nervous system, seen as a sensitive instrument, needs to calibrate itself using natural patterns of matter and energy — natural and naturally representative data — while screens necessarily provide unnatural patterns (this is, synthetic and selected data), which severely damage the calibration process. (Scientific details are in the peer-reviewed paper, “Sensory Metrics of Neuromechanical Trust.”)

The reasons are ordered with the most important ones at the end.

1. Bad Light: Low-Contrast Blue

Low-contrast: Solid, physical objects illuminated by natural light have very high contrast ratios as with the contrast between direct sun and deep shadow, surpassing 10,000:1. The best passively-illuminated screens, like the Kindle Paperwhite, are hundreds of times worse (15:1). A few backlit monitors manage 1000:1 contrast ratios (as viewed in normal light), which is still worse than natural objects.

Blue: The human circuitry for setting day-night patterns (circadian rhythms) is sensitive blue light, which in nature it only sees from dawn to dusk, never at night. Any screen that looks white contains blue light; viewing during the wrong times will damage sleep-wake cycles.

2. Fixed Focus 

Our eyes evolved to look at objects at a whole variety of distances, not just half a meter directly in front of the face. Keeping any set of muscles in exactly the same position for long periods tends to “overtrain” those muscles into less flexibility, and the eye muscles are no different. As a result, screens are increasing both eyestrain (computer vision syndrome) and myopia worldwide.

3. Oculocentric

Normal, physical objects like paper interact not just with the eyes, but with all the senses. Paper makes crinkling sounds when you crumple it, it feels rough or smooth, it may smell of perfume or even taste bitter when you make spitballs, or eat your words. Since the main purpose of brains is to stitch and meld together signals from multiple senses (sensory fusion), using just one sense in place of five is a big mistake. In particular, screens completely leave out the tactile channel of reciprocal touch, the channel primates rely on most for forming interpersonal trust.

4. Too Smooth, Flat and Shiny

Smooth: The mechano-receptors in our fingertips are incredibly sensitive to a wide variety of natural textures. Glass is unnaturally smooth, and that smoothness deprives your skin of essential tactile information. Furthermore, overexposure to a single stimulus mistrains the nervous system.

Naturally writable: You can write on normal physical objects, like paper or whiteboards, which gives your sensorimotor system far more autonomy and control than if touch is missing or clunky, as with screens.

Glare: Our eyes evolved to look at natural objects, very few of which are shiny. Shininess on its own already causes certain kinds of visual miscalibration (see #7 below), but it becomes especially distracting to the visual system when layered in front of what you’re looking at, as with the shiny glass reflections that sometimes make screen-based text hard to read.

Flat: There are almost no truly flat objects in the natural world. If human eyes work best and learn best when looking at a wide variety of natural shapes, then they must correspondingly suffer from hours of looking at the exact same shape, and an unnaturally flat one at that.

5. Fractured in Space and Time

Pixelated: Natural objects have microscopic detail and structure down to the molecular level, containing far more visual information than we can be consciously aware of (hyperacuity). So for the pixelated images of screens, even if the pixels are so closely spaced the screen looks sharp. The nervous system as a whole still isn’t fooled.

Flickering: Screens and their pixels flicker from 50 to 100 times per second, which is faster than conscious awareness, so we don’t see the flicker. Unfortunately, the nervous system is highly sensitive to all changes, especially sudden changes, at timescales yet a thousand times faster. To your nervous system, a plain white computer screen is like a disco strobe at hyperspeed.

6. Edge-enhanced

Objects in the natural world have edges. They don’t have “edge-enhanced” edges, which look weirdly extra-sharp. (To see this effect, find a modern, high-definition display and look closely at a moving football player.) The uncanny sharpness comes from algorithmically adding extra bands of bright and dark that highlight the edge in a flat image — an effective way of tricking a brain’s processing circuitry. But the more a brain gets accustomed to consuming pre-sharpened, unnatural data streams, the less well it can detect and sharpen natural ones on its own.

7. Over-Attractive

Random views of nature are pretty boring and often hard to make sense of (dirt, grass, leaves). Screens, on the other hand, have the boring and ambiguous stuff removed and add in lots of extra-bright colors, eye-catching motions and crisp clear patterns. Unfortunately, what makes something interesting is how unusual it is, which is why we evolved to have an appetite for it. And, as a matter of principle, overdosing on unusual stimuli makes them not unusual anymore, and thereby de-calibrates the nervous system all by itself.

8. Sudden interruptions

In nature, there are no true interruptions. Even a thunderclap is preceded by lightning, and the lightning preceded by a cloud. A wireless interruption like a text or call, on the other hand, comes literally out of nowhere, unpredictably, startling the nervous system deeply and spiking markers of anxiety, like the hormone cortisol. Electrical or not, sudden shocks are always shocking.

9. Persuasive

What appears most often on screens is not just specially selected to make you look at it, but optimized to make you do something: buy, subscribe, vote, retweet or at least look more. That makes it a form of persuasive technology — a technology whose primary purpose is to make people do less of what they want to do, and more of what some business wants them to.

In other words, the purpose of the technology is to control human perceptions, beliefs and behavior. People behave on average as if addicted to screens because their decisions, on average, are controlled by the screens. Persuasive technology does work, and it works by dangling just the right rewards at just the right times, using principles originally discovered with rats and cocaine levers. The main difference is that the “drug” that screens dispense is images, not chemicals. Habit-forming dopamine circuits work the same for both.

10. Anti-Social 

Humans are the most elaborately social animals on the planet. To form trusting bonds, we need to hear and touch each other even more than we need to see each other. By depriving us of those quick-response signals while pretending to “connect” us visually, screens create the worst kind of socio-sensory deprivation, one that addicts people to monetizable social interactions which make them even lonelier.

In summary, there are many straightforward reasons why highly artificial inputs (like screens) ought to be bad for highly-sensitive creatures like us. Furthermore, there is abundant evidence that screens actually do damage human mental health. Practically every possible form of mental illness — loneliness, depression, anxiety, self-harm, violence, ADHD, “spectrum” disorders, OCD — is on the rise, and each is directly correlated with screen exposure (see Sensory Metrics for clinical references). Mental misery is rising everywhere, and fast.

Mobile video in general, and screen devices in particular, represent a peculiar technological pinnacle that works because it interferes with our perceptions and behaviors. Such technology cannot help being bad for us in large quantities.

*[Big tech has done an excellent job telling us about itself. This column, dubbed Tech Turncoat Truths (3T), goes beyond the hype, exploring how digital technology affects human minds and bodies. The picture isn’t pretty, but we don’t need pretty pictures. We need to see the truth of what we’re doing to ourselves.]

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