While designing a UI where data arrives over time in groups of 2, 5, and 10 and gradually converges on the correct value, I wanted it to feel friendly to human users while still giving them a sense of concentration. I tried a number of things and eventually found a compromise that felt right.
- I constrain the magnitude of each individual numerical change so it never jumps too far at once.
- I make that magnitude shrink gradually over time.
- Within that allowed magnitude, I intentionally apply a random value.
The human brain is a prediction machine. It tries to find patterns even in things that look random. I learned that satisfying that tendency is effective for keeping a user focused on the screen.