By removing the recording function from the earliest Walkman devices, Sony produced a device which had a smaller range of uses — but a far greater potential to change behaviour. By narrowing the perceived uses of the device, it meant that it could do only one thing: this made it much easier to adopt the new behaviour — since there was only one possible behaviour to adopt.
People who know a great deal about design, such as the wonderful Donald Norman, spend a lot of time writing about door handles. A good door not only allows you to open it; it also signals to you — without your needing to think about it — whether you are supposed to push the door open or pull it. A plate only allows you to push — so you instinctively push. A protuberant handle is clearly designed to be pulled, so you pull. Very occasionally you will come across a door with what appears to be a handle but which is designed to be pushed open: this will confuse the hell out of you, and for a brief moment make you feel like an idiot. The best thing you can do with such a door is to ‘reduce the affordance’ by taking the handle off. This will make it instinctively much easier to use.
Retro bonus: Here’s one of the first television commercials for the Walkman from 1983, which conveys the small size very effectively, backed by what can only be described as an odd spooky soundtrack…
Finally, check out these 12 vintage Walkman designs.