It’s always nice to discover new functionality in interactive systems, especially when watching people use such systems in the wild. When travelling in an elevator, I recently saw a nice solution to the main problem with elevator user interfaces: how to deselect a mistakenly pressed floor button.
Although elevators have a very simple user interface—press the button that corresponds to the floor one wishes to visit—this simple interface breaks down when passengers mistakenly press the button for the wrong floor. Elevator buttons are either in the default off state or they’re in the lit state after being pressed by passengers. There’s usually no way for passengers to deselect a floor after it’s been selected. Only the elevator itself can deselect the button when it arrives at the corresponding floor.
Like most nice designs, the solution to this problem is incredibly simple: treat each floor button as a toggle button. After pressing an incorrect floor button, passengers correct their mistake by pressing the floor button again to reset it to the default off state. The downside of this kind of functionality is that it’s hidden and therefore not easily discoverable, except perhaps by accidentally pressing the incorrect button again en route to a neighboring button. However, learning from other elevator passengers is a useful and easy way to learn.