Mac’s Petit Inventions: Lock or Unlock

Have you ever double-checked if you really locked a door? That wouldn’t be necessary if you had a lock with a clear indicator that says “I’m locked.” So is there a way to design this constraint into the product?

In the above example, there is no indicator that says which way you should rotate to lock the door. But even when there is an indicator such as a small circle, it doesn’t always mean it’s “locked”. It might mean it’s “unlocked”. So I was wondering if there was a way for anyone to be able to recognize it’s really locked and came up with the following idea:

Actually this does NOT physically prevent the rotation of the handle around its root. This hook is just a fake, but it makes you easily recognize that the door is locked when it’s at the lowest.

So that’s what I thought when reading Living with Complexity by Donald Norman, which I highly recommend.