Peripherisation – how the language of “Edge Cases” has bad consequences for people with disabilities

Alastair Somerville
2 min readMay 31, 2019
“Inquire within” by Lee Bennett is licensed under CC BY-NC-SA 2.0

“Edge Cases”?

I loath the phrase. It’s a way of describing people who do not meet some sense of Normal that designers or providers are thinking of.

At worst, products and services are created that completely fail to be usable by people who are defined as “Edge Cases”. Generally , products and services are designed to be accessible. At best, they are inclusive.

Using the phrase “Edge Cases” has other design consequences tho.

One of them is Peripherisation.

Design that literally places people and their needs at the edges, at the periphery.

You see this is digital and physical spaces. Here are some examples:

  • Wheelchair ramp or access at the side or back of a building
  • Accessible features placed several menus down within Settings of a phone
  • Priority service dependent on self-declaration of disability
  • Accessibility need questions at the end of an online ticket booking system
  • Accessible seating/wheelchair spaces at the front/back/side of a cinema or theatre
  • Boarding last onto a plane or train

First, last, back, front, side – all peripheries. All edges.

Talking of “Edge Cases” leads to design that places people on the edges.

In all these cases, designers have taken a view that this is the reasonable and practical approach. Yet it isn’t.

Disability is ordinary and is central to human life.

If we keep placing people with disabilities at the peripheries (physically and digitally), how do we expect them to be part of the social and economic life?

“Edge Case” as language has consequences. It enables peripherisation and thus embeds exclusion into even the most inclusive products and services.

The language you use to describe a problem creates the frame within which you design the solution. If you speak of “Edge Cases”, you create products at peripheries. The way you talk becomes the way you make.

Involve diverse group of people to check that you do not use language that has this bias.

Edit 4th June 2019

Reversing Peripherisation

Screen grab of Tweet about Accessibility & Setup Buddy

It was Apple’s World Wide Developers’ Conference announcement last night.

There was lots about IOS13 and, in amongst it all, the announcement of the shifting of Accessibility from a submenu to main menu in Settings. Also putting accessibility features into a Setup Buddy for all new users.

This is demonstrable action to reverse Peripherisation. Putting accessibility in the centre of design not at the edges.

I’m happy to see this happen.



Alastair Somerville

Sensory Design Consultant, usability researcher and workshop facilitator. Twitter @acuity_design & @visceralUX