wanghaisheng Ability Spectrum Mapping
Map how a feature performs across the full range of human ability — from full capability to no capability in each dimension — to identify where the design starts to break down and who gets excluded.
Why a Spectrum
Accessibility is not binary. It's not "can see" vs "blind." The reality is a continuous spectrum:
- Full vision → needs glasses → low vision → legally blind → no vision
- Full hearing → mild loss → moderate loss → severe loss → deaf
- Full dexterity → mild tremor → limited range → single hand → no hands
- Full cognition → mild difficulty → moderate difficulty → significant support needs
Products don't go from "works" to "doesn't work" in a single step. They degrade gradually. The spectrum map shows you exactly where your design starts failing and for whom.
How to Build an Ability Spectrum Map
Step 1: List Core Tasks
Identify the 5–10 most important tasks a user performs with the product.
Step 2: Define the Spectrums
For each relevant ability dimension, define 4–5 points:
Vision spectrum: Full vision → Corrected vision → Low vision (magnification) → Very low vision (screen reader + some vision) → No vision (screen reader only)
Hearing spectrum: Full hearing → Mild loss (louder volume) → Moderate loss (captions needed) → Severe loss (captions + visual alerts) → Deaf (fully visual communication)
Motor spectrum: Full dexterity → Reduced precision (larger targets) → Limited range (keyboard only) → Minimal movement (switch or voice) → No hand use (eye tracking, sip-and-puff)
Cognitive spectrum: Comfortable with complexity → Prefers simplicity → Needs plain language → Needs step-by-step guidance → Needs significant support
Step 3: Map Each Task
For each task × ability point, rate:
- Works well — no barriers
- Works with friction — possible but harder than it should be
- Works with workaround — user must find their own solution
- Fails — task cannot be completed
Step 4: Identify the Breakpoints
Where does the design shift from "works" to "fails"? That breakpoint is your accessibility boundary. Everything to the right of it is excluded.
The goal is to push that boundary as far right as possible.
Presenting to Stakeholders
The spectrum map is a powerful communication tool because it shows:
- Exactly how many users are affected at each point
- Where investment in accessibility has the highest return
- That accessibility is a continuum, not a checkbox
- Which fixes would move the boundary and include more people
Template
| Task | Full vision | Low vision | Screen reader |
|---|---|---|---|
| Search for a product | Works well | Works with friction (small targets) | Fails (search suggestions not announced) |
| Complete checkout | Works well | Works well | Works with friction (form errors not associated) |
Assessment Questions
- Have you mapped core tasks across at least vision, motor, and cognitive spectrums?
- Can you identify the exact breakpoint where each task fails?
- Do you know which fixes would include the most additional users?
- Can you communicate the spectrum to stakeholders without technical jargon?