After the Mac was introduced in January 1984, we were excited to see people's first reactions to our pride and joy. Computer users were accustomed to the IBM PC's command-line interface, so we wondered how they'd respond to our point-and-click, drag-and-drop GUI. I was particularly curious about their experience with the Finder—what they found compelling or difficult.
In the week after launch, we visited many stores and found a consistent issue: every Mac's floppy disk had a garbled name like ";lkakl;rt;klgjh", as if someone had mashed the keyboard randomly. Because that's exactly what happened.
The Root Cause
- The startup disk appeared selected by default in the Finder (top-right corner of the desktop).
- The Mac used modeless interaction (learned from Larry Tesler's Smalltalk group): typing while a disk was selected would rename it.
- New users instinctively typed to explore, unknowingly renaming the disk.
The Lesson
Our user testing missed this flaw—participants were too familiar with the Mac to make such mistakes. We hadn't validated the Finder against the "Mom test": Could an average person figure it out unaided?
The Fix
I rushed back to the office and built a new Finder version requiring an extra step to rename disks (and addressed other bugs).
This experience taught me two things:
- Even "intuitive" designs need rigorous real-world testing.
- Modes have merit—in some cases, they prevent unintended actions.
A humbling lesson, indeed.