Wired magazine has a fascinating look some of the design behind the Apple watch. One of the challenges the team had was deciding how notifications – buzzes against the skin of the wrist – should be differentiated. The buzz for a calendar alarm shouldn't be identical to the buzz for a phone call.
Of course, there's the question of how a tweet notification should feel:
Apple tested many prototypes, each with a slightly different feel. "Some were too annoying," Lynch says. "Some were too subtle; some felt like a bug on your wrist." When they had the engine dialed in, they started experimenting with a Watch-specific synesthesia, translating specific digital experiences into taps and sounds. What does a tweet feel like? What about an important text? To answer these questions, designers and engineers sampled the sounds of everything from bell clappers and birds to lightsabers and then began to turn sounds into physical sensations.
[My emphasis added.]
Apple made a decision of what a tweet should feel like, but idk.... what do you think?