One in twelve men can't read your colour-coded design the way you intended.

That's not a niche accessibility footnote — it's a quiet, persistent failure woven into the fabric of everyday UX. Colour is one of the most powerful tools in a designer's kit, and one of the most routinely misused. This episode of HCI Explained asks a deceptively simple question: if you design with colour alone, who gets left behind, and why does it keep happening?

Hosts Mara and Jon walk through the human–computer interaction research on colour perception and contrast, unpacking what "colour blindness" actually means (it's rarely true blindness), how contrast ratios became a cornerstone of accessibility standards, and why well-intentioned design teams still ship products that exclude millions of users. The episode moves from theory to practice without getting lost in technical detail — this is a conversation for curious people, not specialists.

A few of the threads we pull on:

• Why the 1-in-12 statistic is both accurate and misleading, and what the real number looks like when you count everyone affected

• The everyday analogy that reframes how you think about colour dependency in interfaces

• A real product launch where colour-only feedback caused genuine, documented user confusion

• The tension between visual delight and functional equity — and whether designers are ever forced to choose

No jargon goes undefined, no conclusion is handed to you cheaply. Just a careful, unhurried look at something that shapes every screen you use.

Pull up a chair — this one's worth thinking about.