Mutual Aid and Human-Centered Learning for Neurodivergent and Disabled People

Pattern 39 — Average User Fallacy

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Intent

Stop designing for a statistical midpoint that describes nobody, and design for the range of real people the system will actually meet.

The Pattern

Systems are built for a user who does not exist. Not a typical person — no person. The average is a property of a dataset, not a description of anyone in it.

Our own statement of this is blunt: there is no average user, there are only real people in real conditions. Average describes a central tendency. It does not describe how any single individual actually functions — not with a spiky profile, fluctuating capacity, context-sensitive attention, or sensory variability.

The fallacy is not the arithmetic. It is the move from this is the mean to this is the person we are building for. Nobody is average on every dimension at once, so a design tuned to the midpoint of each one fits nobody at all.

The myth survives because it makes systems easier to manage. Standardized tests assume standardized learners. Behaviour systems assume standardized regulation. Productivity metrics assume standardized energy. As we put it: averages make spreadsheets easier, they do not make lives easier.

And the cost lands on people, not on the model. Disabled people are labelled noncompliant, neurodivergent people disruptive, students behind, workers unproductive. The variation was always there. The design simply had no room for it, and the shortfall got written down as a property of the person.

Why It Matters

When a system is built for the average, people may:

be told a design works because it works for most
have a real barrier dismissed as an edge case
be offered an accommodation for something that should not have excluded them
fail a process that was measuring fit, not capability
be counted as an exception to a rule that has many exceptions
stop reporting problems that are always answered the same way

An edge case is usually a person. Enough of them and the edges are most of the distribution.

Forces

Designing for one imagined user is cheaper than designing for a range.
Variation is real; budgets and timelines prefer it not to be.
The midpoint is easy to name and a range is not.
People excluded by a design are rarely in the room where it is evaluated.
Every unaccommodated person can be reclassified as atypical.
Nobody is average on more than a few dimensions at once.

Problem

How do we design for the actual distribution of people rather than for a statistical ghost at its centre?

Solution

Design for range instead of for average. Offer multiple ways to participate, assume capacity fluctuates, build in recovery time, make information flexible and multimodal, and normalise movement, pacing and variation.

This is not adding accommodations afterwards. It is designing from the start for real human variability — and when you design for the edges, the middle works better too.

Test at the edges deliberately, because that is where failures become visible. This is the design stance behind Environment Fit and Spiky Profiles.

What This Looks Like

In physical spaces

Provide more than one kind of seating, lighting and acoustic setting.
Assume some people will need to leave and return.
Do not make the adjustable option the conspicuous one.
Design the route that works under load, not only the direct one.
Never treat one body’s comfort as the room’s specification.

In digital spaces

Let people change text size, motion, contrast and density.
Do not time out a task that a person may need to pause.
Support keyboard, pointer, touch and voice rather than assuming one.
Let the same information be read, watched or listened to.
Test with the settings people actually use, not the defaults.

In social and organizational practice

Ask who this design would exclude before asking who it serves.
Count the people who never made it into the sample.
Treat a repeated complaint as a design finding, not a personality.
Give more than one route to the same outcome.
Do not require a diagnosis to unlock a reasonable default.
Never describe an excluded person as an edge case in their hearing.

Implementation Notes

Find the imagined user hiding in the requirements.

Ask:

What is this design assuming about attention, energy, pace and sensory tolerance?
Who was in the sample, and who could not have been?
Which dimensions did we take the midpoint of, and did we take several at once?
What happens to someone in the tail on any one of them?
Is the flexible option the default or the exception?
How would we know if the people we excluded simply stopped coming?

A good test: if the design works for the average on every axis and fails anyone who is unusual on one, it was fitted to a composite that no person can be.

Signals of Misuse

This pattern is being violated when people hear:

“It works for most people.”
“That’s an edge case.”
“We can’t design for everyone.”
“Most users don’t need that.”
“That’s what accommodations are for.”
“You’re the only one who’s mentioned it.”

The last one is usually true and means nothing — it describes who complained, not who was affected.

Consequences

When this pattern is honored:

variation stops being reclassified as deficiency
fewer people need a special case because fewer are excluded by default
designs get tested where they actually fail
the flexible option stops being a favour
the middle benefits from what the edges required
exclusion becomes visible as a design choice

When it is ignored, a system can report high satisfaction among the people it did not exclude.

Anti-Patterns

Designing to the persona and calling it research
One-size-fits-all defaults with opt-out adjustments
Accommodation as a retrofit process
Edge case as a dismissal
Sampling only the people the system already serves
Standardized conditions treated as neutral conditions
Averaging several dimensions into one imagined user

Design Moves

Strategies for designing across a range rather than to a midpoint.

See recipes:

Related Environments

Environments where the imagined average user does the most damage:

Related Experiences

Experiences produced by designing for the midpoint:

Patterns Below

Patterns Above

Spiky profiles describe why no one is average. The average user fallacy is what institutions build once they have forgotten it.

Related Patterns

Related Principles

Design Is Tested at the Edges
Broken Systems, Not Broken People
Human Needs, Not Special Needs
Design for Range