One of the cleanest and most efficient examples of good Visibility of System Status designs is the light switch. Obviously, in the case of most lights, the system is either off or it’s on and there’s no in between (ignoring dimming lights). Now, despite the binary of the system, not all light switches are created equal. The photo attached displays a light switch panel that contains the light switches corresponding a particular light system. The word “OFF” is visible only when the switch is in the down, or OFF position, and the word “ON” is visible only when the switch is in the up, or ON position. Furthermore, thanks to the additional labelling of the control panel (a hack, if you will), the user is never confused about which switch responds to which lighting system.

Below, you will find a picture of a mechanical fireplace that is mounted on walls all around Mather House. This fireplace is constantly adjusted by students and yet terribly violates the Visibility of Systems principle. As the photo on the left shows, the only buttons that seem to relate to adjusting the heat setting are the hard to press — and O buttons. They are not labelled and it is unclear which button lowers and which raises the heat.

The Mather House staff have conveniently placed an instructions sheet next to the fire place (bottom right photo) which explains the fireplace actually only has three settings: off, low, and high. Furthermore, it inexplicably has two buttons that turn the heat off (the small O and the on off switch). Thus, the only way people know what heat setting the fireplace is on (if at all) is to press the — button and stand with their hands in front of the fireplace to guess if it’s warming up or not.

In practice, when students want to adjust the heat, they will first press the off button (the O) to “reset” it, then they systematically press the — button and put their hand in front of it to feel if the fireplace is getting warmer or not.

The best way to redesign this control panel is shown in the drawing below. Here, there is only one on and off switch. There is also only one switch that toggles between Manual and Remote. Then, the newly designed panel has a slider with only three grooves: no heat, low heat, and high heat. See leftmost photo. Furthermore, when the slider moves to a new setting, the fake fire display will actually respond by intensifying (or diminishing) its flames to correspond with the new heat setting. For example, the no heat has wispy flames that are bright green (top right), low heat has moderate flames that are orange (mid right), and high heat has vivacious flames that are red (bottom right). For people with color blindness, the height and intensity of the flames will allow them to understand the setting the fireplace is in just by looking at it.