Recently I enabled an accessibility option to map "Toggle grayscale screen filter" to the triple tap of my iPhone's home button, and within a few dozen seconds, after acclimating to the change and finishing whatever it was I had needed to do on my phone, I set it down. I say this as someone who absent-mindedly swipes between home-screen panels and refreshes twitter and facebook even when I don't plan on reading whatever pops up.
I still picked it up easily when I needed to use it: to send a text; read an email; or respond to a twitter DM or slack message. I still easily used the map features, and still browsed instagram briefly (which looked far more artsy in coerced-b&w), but found myself almost always staying more on task and putting my phone down when I was done with that task.
On further experimentation, I've realized this is because, from a biological standpoint, your phone is usually packed with more vibrant colors than anything in your environment. Even bright magazine covers pale in comparison to the phone screen. The lizard-brain in us sees the iPhone's home screen covered in small, bite-size applications, all in tantalizingly vibrant colors, and thinks simultaneously "nutritious berries" and "poisonous animals", both things we have become evolutionarily primed to notice and maintain focus on.
After some time on your phone, the world seems to be dulled, and for good reason. Compared to your phone, the colors of the real world are much duller. They're lower contrast less saturated, and less clean.
Turning on the accessibility feature for black and white filtering flips this dynamic on its head. Suddenly, your eyes are easily drawn away from your phone. Like a newspaper, the act of looking away from it fills your eyes with comparatively high color and brightness. The innate draw of your phone becomes solely based on the information you can glean from it and the things you can do with it, not how instinctively interesting it is to look at.
Obviously using your phone is generally a pleasurable activity, and I'm not advocating for less phone usage. I'm largely pointing this out because it draws into stark attention how much color affects our enjoyment of an app, and how bright, vibrant colors can really draw us in to a device, or an app, or really anything. Color matters a lot; not just how we use it, but that we use it.
As much as I don't think phones are bad, I think they can get in the way when you're trying to enjoy a book or movie or game, or are trying to focus on something else. If you want to be less drawn in by your iPhone, or see this phenomenon for yourself, you can map your black-and-white screen filter to a triple-tap of the home button by:
1. Settings > General > Accessibility > Display Accomadations > Color Filters > toggle 'Grayscale' 2. Settings > General > Accessibility > Accessibility Shortcut > toggle 'Color Filters'