The Windows mouse pointer arrow is asymmetrical: why and who invented it

The image highlights how the pointer used on Windows is asymmetrical. Credit: MSPowerUser.

The December 9, 1968during the conference organized in San FranciscoCalifornia, from ACM/IEEE (Association for Computing Machinery/Institute of Electrical and Electronics Engineers), the engineer Douglas Engelbart presented the first prototype of the mouse and the graphical user interface that would be possible to use thanks to it. The initial pointer – i.e. the symbol that appears on the screen and indicates where the pressure of a mouse button acts – was a black arrow pointing up, but with the introduction of the Xerox Star in the 1980s, the low resolution of the screens made it necessary to tilt it to improve visibility. The arrow became iconic with Applewho implemented it on the Apple Lisa and then on the Macintosh and, subsequently, it was also used by Microsoftwhich for its Windows operating system adopted a slightly different design, with an asymmetric arrow so that it appears more proportionate, correcting an “error” of our visual perception and thus ensuring a better optical balance.

Who invented the mouse pointer

The December 9, 1968 Mr Douglas Engelbartinventor of the mouse, in addition to presenting the first prototype of the popular input peripheral, also presented to the world thegraphical user interfacea convenient way to navigate and use computers through the screen. As can be seen from the excerpt of the presentation (available at the end of the chapter), which went down in history as “The Mother of All Demos”, that is, the mother of all demos, initially the mouse pointer consisted of a black arrow pointing up. This would have allowed the first users of the graphical interface to precisely indicate icons and symbols to click.

When the mouse was marketed starting in the 1980s, with the Xerox StarEngelbart realized that the low resolution of the screens of the time did not favor a good display of the vertical arrow and, for this reason, he decided to tilt it with the tip towards the upper left corner. Since then, the mouse pointer, as we know it today, has conquered the entire computing industry with its iconic slanted shape.

Speaking of its diffusion, the arrow-mouse combination initially won over Apple which, thanks to Steve Jobsunderstood the potential of Engelbart’s invention and developed its use. The arrow adopted by Xerox was improved graphically and, while maintaining the black colourwas embellished with a white border which increased its visibility. After purchasing the license for the invention for a sum that would have approached 40 thousand dollarsmouse and pointer made their appearance on the computer Apple Lisa (1983) and, later, also on Macintosh (1984).

Subsequently, with the introduction into the 1985 of the operating system Windows 1.0Also Microsoft adopted the use of mouse and pointer. In this case, Bill Gates’ company decided to use a color scheme opposite to that of Apple, with the inside of the arrow is white and the outline is black. Furthermore, compared to the arrow on macOS, the one on Windows had a longer tail.

Because on Windows the arrow is asymmetrical

Speaking of aesthetic differences, perhaps you too have noticed that the arrow on Windows is asymmetrical. To go into more detail, the lower part of the arrow on Windows is slightly less inclined than the direction of the tip, a peculiarity not present on the macOS arrow. The reason for this graphic choice is to be found in the fact that the human eye sometimes makes errors in evaluation (many of which give rise to so-called optical illusions) and sees asymmetrical figures which, in reality, are perfectly symmetrical.

As counterintuitive as the reasoning may seem, to correct this evaluation error committed by our brain when observing an image, in this case the mouse pointer icon, Microsoft designers decided to obtain the correct optical balance using a asymmetric arrow.