How the evolution from knobs to touchscreens failed many of us
In science fiction, the future is usually sleek, filled with glass screens and dazzling visual interfaces. Over time, designers and manufacturers have done their best to bring that vision to household objects. From smartphones to kitchen appliances, glass screens have become the default interface for more and more of our everyday devices. But what looks cool and modern to some has created real barriers for others.
From Knobs to Pixels
Let’s rewind to the heyday of the American space program, when interfaces were full of physical knobs and switches. Each one had a clear, single function— whether you turned it, pressed it, or slid it, every control corresponded 1:1 with a specific action. A glimpse inside a space capsule would have shown rows upon rows of controls covering every available bit of space. An astronaut would have needed months of training to gain the familiarity needed to navigate this interface comfortably enough for space flight.
Still, by the 1970’s, stereos and automobile consoles had become light versions of the space capsule aesthetic, making rows of uniformly-designed knobs and switches available to any user. Common use of icons and acronyms shortened the learning curve, enough that a first-time user could recognize at least half of the controls on sight.
By the late 1980’s graphical user interfaces (GUIs) became common, with the earliest designs incorporating literal versions of physical controls like switches, sliders, and knobs. With graphical interfaces, the tight 1:1 relationship between a control, its location, and its function became an artifact of the past. Not only did the location of a control vary from one screen to the next, but a primary button could mean “Save” in one context and “Delete” in another.
Graphical user interfaces were highly successful at letting users manage only the controls needed for the task at hand, as opposed to the space capsule arrays in which every control was visible at one time. For those who could understand that controls could vary in functions from context to context, graphical interfaces greatly reduced the cognitive load.
Image source: Wikimedia
With the advent of touchscreens, keyboards and pointing devices were replaced by direct contact of a human digit on a glass screen. Science fiction movies had previewed this evolution by showing touchscreens in their portrayals of interfaces of the future. By the early 2000s, interfaces included the lavish wall-to-wall touchscreens of the Star Trek franchise and the sweeping gestural interfaces of The Minority Report movie.
With this futuristic aesthetic came the feeling that glass interfaces are cooler, more modern, more desirable. Manufacturers love them because they’re cheaper to make, easier to service, and easier for software updates. Consumers love them because they’re easier to keep clean. Not surprisingly, touchscreens made their way into the design of everyday household objects like thermostats, toaster ovens, and stoves —where they’re not needed in the slightest.
Even appliances that still have knobs, like washing machines, now hide their key info—like temperature, time remaining, or cycle —behind a glossy, unreadable sheet of glass.
Why Glass Fails
The evolution from knobs and switches to glass controls brought with it a deep flaw: glass interfaces look cool, but they rely entirely on vision.
Without sight, they turn into smooth, inscrutable surfaces with no tactile feedback, no landmarks, and no obvious way to interact. For millions of people, this shift from physical to visual-only controls has turned everyday tasks into frustrating or even impossible challenges.
In design-speak, glass interfaces fail because they rely exclusively on one single modality — visual — for communication. Unlike smartphones, which use other modalities like audio and haptics (bumps and vibrations), most touchscreen interfaces are strictly visual.
This problem isn’t just confined to home appliances. Out in the world, touchscreen elevator panels are common. They’re futuristic looking, but totally unusable without eyesight.
Touchscreen kiosks are now common — and many are literally just iPads behind glass, encased in a housing that blocks screen readers or ports for accessible headsets.
Since most touchscreens have only one modality — visual — they’re less robust than a multimodal user experience that includes sounds and haptics. Without audio or other modalities, then the touchscreen becomes a pane of dead glass.
Talking interfaces such as screen readers and button name announcements are essential for blind users. That’s why we need interfaces that adapt—ones that can switch from visual to auditory, or that can mix both. Just as it’s important to support those of us who don’t have eyesight, it’s best to offer a choice, as some sighted users find talking interfaces to be chatty and annoying.
In architecture, we talk about universal design: a building that works for everyone, regardless of ability. Digital devices have a similar opportunity. Unlike buildings, software and digital products can change depending on who’s using them.
Should we move away from glass screens?
Some think so.
A few automakers have been scaling back their reliance on touchscreen dashboards. There’s been a shift back to physical controls, either as a replacement for key functions in the glass interfaces, or as a redundant backup. Exposed to extreme heat, cold, UV, and vibration, touchscreen controls may not be rugged enough for critical functions. A vehicle’s screen can fail, leaving occupants without navigation or climate control, causing real problems and discomfort within minutes.
But perhaps there’s another option — how about making glass interfaces smarter and more inclusive?
We already have the technology. Smart speakers and phones use wake phrases like “Hey Siri” or “OK Google” to switch into voice command mode. The limitation isn’t technology — it’s cost. Amazon, Google, and Apple charge third-party vendors steep fees for integrating with the home automation platforms that use those proprietary phrases.
Apple’s iOS also uses something called the rotor—a two-finger gesture that mimics turning a knob. It gives blind users access to different controls like volume or speech rate. Imagine applying a similar gesture to other glass interfaces—like elevators or appliances—to switch into an audio or voice mode.
The hardest part isn’t inventing a new gesture—it’s getting manufacturers to agree on a standard.
We care about this at Standard Accessibility Reporting
Few things can land a product a one-star review faster than it failing to work for consumers. Since they lack a backup, single-modality glass interfaces are an outright failure for people who cannot see, and can be difficult to use by people with other types of disability.
If you’re in the market for any product with or without glass interface, it would be great to know in advance what interface features are available and how accessible it is. At Standard Accessibility Reporting (SAR), we’re creating the standards for reviewing products and ways for consumers to know before they buy.
How would you score a glass interface
- If you were to rank an interface that only works one way, how many stars would you give it?
- If you would consider giving it more than one star, then we really need to hear from you to explain why.
Join our discussions as we work on new industry consensus standards at our member organization, SAR.