Ever wondered why your computer mouse cursor points slightly to the left?
There’s a reason for that, going back to a 1981 research paper published by Xerox. (Xerox famously invented the rolling ball mouse, an idea that was later developed with more success by Apple.)
Turns out that the arrow looks sharper when the pixels are stacked in such a way as to create one straight, vertical edge to the arrow head. Here is the schematic from the 1981 Xerox paper:
This little snippet of history was explained recently by Bart Gijssens, a Belgian software developer, writing on Stack Exchange, the site for coders:
The mouse, and therefore the mouse cursor, was invented by Douglas Englebart, and was initially an arrow pointing up.
When the XEROX PARC machine was built, the cursor changed into a tilted arrow. It was found that, given the low resolution of the screens in those days, drawing a straight line and a line in the 45 degrees angle was easier to do and more recognisable than the straight cursor.
Gizmodo (via Ars Technica) noticed that when a straight-up arrow was used on early computer displays, it got “lost” among the text:
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