Up is Down

I was in an elevator the other day and I noticed something about the digital numbers. I was on the 7th floor going down. Inside the elevator was the standard 7-bar number display indicating the current floor,

Digital number 8

However, from the angle I was standing, the top right bar was not visible. Like this,

Digital number 8 covered

The arrow was indicating that the elevator was traveling downward, but with that bar in the way the numbers can appear to be going upwards, not downwards. It is an ambiguity, as without that bar, 6 is equivalent to 8 and 5 is equivalent to 9. One version is covered, the other is not.

Counting up/down Counting down

At first I thought this was simply some kind of quirky behavior of the elevator. "Why is it going up when the arrow points down? Seems like bad design to me!", I thought — until we got to floor 4, where it was obvious what was going on.

"Oh... now I feel foolish."

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Chris Wellons