Not only customers provides feedback to you but you provide feedback to the customers too. Website or a doorbell, it is always better if your device or website responses on user’s action in a friendly manner. If you don’t hear a sound or at least don’t see a light indication then your efforts to pressing the doorbell knob seems to be in vain. If shopping cart at your web-shop doesn’t show ‘thank you’ message it may kill your business. So why on Earth we still see contact forms which do not provide any feedback at all? Why buttons on some pages do not react immediately with any kind of ‘I’m working, please wait a sec’ message? Change color or ‘circling’ icon usually enough, no need in text messages.
Despite real life things engineers usually don’t do such mistakes, sometimes they do. Just for example:
This button should be pressed to let bus driver know someone in the bus would like to take off. We know that there’s nothing perfect in this World and sometimes such systems are broken. Without the confirmation you don’t know whether you’ll take off where you need or will have to go back. There’s a good example how it can be done:
If you are going to produce a device or software please remember to provide feedback. Ideally with all available senses. On physical device it can be sight, hearing and touch – you can feel with your fingers that the button is pressed (also, there may be a Braille text on the button), you always see in which state the wall switch is, a smartphone can change color of the element, produce sound and vibrate. Not to be annoying, add possibility to disable e.g. sound and vibration, but for people who can’t hear or see well this small and usually cheap in development option will be quite helpful.