chapter 4
Accessibility in hardware
People don't all interact with the world through the same default keyboard, mouse, screen, and speaker. Here's a tour of the assistive hardware you'll see and the design principles behind it.
Input — how people tell devices what to do
Switches
A single big button (or sip-and-puff, or head switch) that scans through options. One button = a whole interface.
Eye-tracking
A camera follows the eyes; dwelling = a click. Used by people with ALS, severe paralysis, and others.
Voice control
"Hey Siri, scroll down." Built into every modern OS — great for hands-free and motor disabilities.
Adaptive controllers
Xbox Adaptive Controller, PlayStation Access — large buttons + jacks for any switch or pedal.
One-handed keyboards & trackballs
Half keyboards, chord keyboards, and big trackballs for limb difference or tremor.
Braille input
6 keys = the 6 dots of a braille cell. Fast for trained users.
Output — how devices tell people what's happening
Screen readers
JAWS, NVDA, VoiceOver, TalkBack — read the screen aloud. They depend on good HTML.
Refreshable braille displays
Pins pop up to form braille cells in real time. Quiet, private, perfect for code.
Hearing aids & cochlear implants
Many stream Bluetooth audio. T-coils pick up induction loops in venues.
Captions on everything
TVs, glasses (XRAI, Captify), phones (Live Caption). Live = realtime; closed = togglable.
Haptics
Wearables that buzz patterns — alerts for Deaf users, navigation for blind users.
Large print & high-contrast displays
For low vision; OS-level zoom and color filters help, dedicated devices help more.
Mobility & sensory tools
Manual & power wheelchairs
Each one is custom-fit. Don't lean on someone's chair.
Walkers, canes, crutches
Mobility aids vary day to day.
White canes & guide dogs
White cane = blind/low vision. Working dogs aren't pets.
Prosthetics
Mechanical, myoelectric, or smart — and very personal.
Noise-canceling headphones
Sensory regulation tool, not antisocial.
Stim toys, weighted lap pads
Help focus and regulate.
Universal Design — the 7 principles
Coined at NC State, these are the design north star. Aim for a product that works for the widest range of people without needing special adaptation.
1. Equitable use
Useful and marketable to people with diverse abilities.
2. Flexibility in use
Accommodates a wide range of preferences.
3. Simple & intuitive
Easy to understand regardless of experience or focus.
4. Perceptible information
Communicates effectively in multiple senses.
5. Tolerance for error
Minimizes hazards from accidental actions.
6. Low physical effort
Used efficiently with minimum fatigue.
7. Size & space for approach and use
Appropriate for any body, posture, or mobility.