This should go without saying, yet apparently it doesn’t.

Design Rule #13: When a user gestures or fills out a form or clicks a button or speaks their audio input or whatever…give them appropriate feedback.

Of course, the word appropriate is subjective. How do you know how much feedback to give? Let’s look at the extremes:

1. Very little or no feedback. The user would say, “Did it work?”. Confusion is the normal result. I find that engineers often think that it’s obvious and minimal feedback is fine. This is incorrect and will lead to technical support calls.
2. Too much feedback. Sometimes, every single gesture is met with a modal saying, “It worked!” with an OK button. This is obnoxious after a while. Your system shouldn’t be annoying. It should be polite and responsive. (Not in the mobile way, I mean in the ‘it responds to you’ way)

Here is a handy chart to understand the right level of feedback.

Good feedback should use animation when possible. Google Material Design is a great pioneer in this. Use their calculator. It has subtle but noticeable feedback with each press of a number. Contrarily, when I use Skype, the feedback is far away from the action and very hard to notice.

It’s a balance and part of the art and craft of design is striking that Goldilocks level where it is just enough, but not more.