The Snow Is In Dotted Lines
Last night I took the dog for a walk, and the awful, cold, stinging snow was all coming down in dotted lines:
This is not an artifact of the camera, but is how it looks to the eye also. So, how? Why? Well you’ve probably figured out it’s not the snow, but something else.
It’s the light. I have an LED flashlight illuminating it.
Technology Is a Trick
Not at full power.
LEDs at lower power are not. See, incandescent bulbs put out less light when you turn down the voltage. LEDs don’t work so well like that, so the normal way to make them dimmer is to make them blink. That’s because LEDs turn on and off crazy fast. 20 nanoseconds is typical. Some turn on in a matter of picoseconds. So, instantly.
If you then turn them on and off, so the off cycle is about half the time, then that’s 50% brightness. Oh, and there’s no startup cost — no extra power consumption from start — so it uses 50% of the power as well.
If you do that several dozen times per second, it’s too fast for people to see. Just like movies or TV are static frames projected fast enough that we perceive it to be continuous motion.
Print has always done this sort of trick also. There’s no continuous tone pictures, but just lots of dots, too small to see. Have you looked closely at your computer monitor lately? No, closer…
We all know machine pixels are not of the color they appear when you zoom into photoshop or take a screenshot. They are made of little bits of color. Sub-pixel rendering is even more of a lie.
Understanding Technology, Ethics, and Human Factors
Or is it?
Sure, there’s lots of misuse of tech for evil these days. It’s ruining democracy, and ruining the world in fact. So, I for one have been really thinking harder about the ethical choices we make in design.
But back up a step: What is the point of many of these systems? They do work, for humans. The entire point is to be useful, and usable, to humans.
These tricks are just engineering to make any technology work. Not to trick people, but to trick the technology into being human-centric.
New Technology, New Design
Humans don’t change. If you understand how people see, hear, feel, perceive, understand, process then you will understand them forever, whatever the context.
But technology absolutely changes. A lot of my work on the touch research was understanding that we’d made absolute truth out of things that were only the intersection of humans and technology. Finger sizes, for example, mattered a lot back when the technology was IR grids. It’s entirely irrelevant now, so is very bad that there are ISO standards around touchscreen design that have that baked in.
Back to LEDs, blink is another one of those old standards we assume works, but doesn’t. Check out how say… a railroad crossing signal works:
Two things you should see here. First, there are paired lights. The red light is never off, but trades with the other. You also have a backup in case one burns out, but when working properly, always some light.
Now, compare to the LED at the top of your phone, or anywhere else you see them used to announce things. They are always alone, so during the off cycle, if you just glance over, you see nothing. No light. I have — many times in usability tests — seen people miss blinking lights over and over again, for minutes.
Thee other thing you’ll notice is the lights do not blink. They are incandescent bulbs (or similar technology) and take a long time, up to 2 seconds, to get to full brightness. They turn onnnnn…. and offff…..
This is not just some weird artifact, but a good thing we used. Car turn signals (and lots of other annunciators back in the day) relied on this a lot:
How long is the Off cycle here? Almost zero. The blink is not on/off but the “motion” of the light fading in and out.
This is how all blink used to work. All the standards we still use were written to assume this. But LEDs don’t work like that because they turn on and off instantly. So, blink is harder to see, and the world is more dangerous.
Unless you know this and work around it. When I have to design blink systems (as LEDs or just for animation) I emulate the incandescent system and ramp the light output.
Understand technology to design for humans.