Microinteraction is a definite, tiny action of your interface. Saving, volume setup, incoming letter sound, “Loading…” progress indicator, tweet sending, anything at all. The more competitors you have, the more it’s important to have cool microinteraction features. But still, the fewer of them, the better — they should exist only for common aim’s sake.
Trigger is some prominent icon for one microinteraction, for example, a close window button or «Home» button on a smartphone. In the majority of cases it’s just a banal button. An action can’t be modal (various) otherwise it’s not a trigger.
It’s great if a trigger shows what’s happening with a trigger right now. For example, before entering a cart, we see how many goods are there.
Triggers may be invisible. E.g.: smartphone gestures, Siri or «ok, google, ..». Invisible control elements should be detectable as far as possible. For example, you can detect a list update while trying to scroll it higher than the first element.
Affordance is a case when trigger-icon is similar to what it does. Just the way shopping-cart in an online-shop is similar to a cart in a supermarket. Icons should be identical to the real life objects or be well-known to users. I.e. it will be a hindrance to usability, if you make a super creative checkbox where instead of a tick something incredible happens.
You should better avoid text in interface, if everything is pretty clear without it. The right icons will perfectly do.
Use already existing triggers for sending a new message. There’s no need to create new ones. Let’s assume you need to say that registration for World Usability Day 2014 will start on a particular date. Organizers must have written it right on the registration button.
More and more triggers aren’t user ones anymore, they’re initiated by a system — for example, push-notifications about new letters — trigger itself is watching updates so you don’t need to check anything. Or deeming display due to being inactive for several minutes.
Now you know that all these simple and evident things are called microinteraction and their triggers. Maybe it’ll be easier to explain yourself with colleagues.
Sound and vibrate
One of the most widespread feedbacks is an error message. It’s a shame! It would be better if there were more positive feedbacks.
There are good thesis examples from Jef Raskin which state that if a user sees error message, it means you’ve designed interface wrong: you may connect lightning cable in iPhone using any side you want (unlike USB) and Gmail notifies in advance that there’s no mentioned attachment in the letter — you’ve wrote about something «attached», but there’s no attached files.
Errors should be shown only in cases when system itself can’t fix them. For example, Meetup automatically widens search radius, if the chosen radius has nothing to offer.
But sometimes errors “teach” a user. It may happen but the key thing here is that consequences should be harmless — a dishwasher won’t open if you try to do it and won’t hurt you but only starts twinkle.
Don’t use negative words like “error” or “warning” in the feedback.
Don’t use personal pronouns. A phrase “Wrong password” is better than “You’ve entered a wrong password”. But it would be better if you make an accent on an action: “Enter a password one more time”.
Spy on users
There’s no need to start from scratch. Always ask yourself — what do I know about users before the beginning of microinteration? Platform, device, time of the day, location…
Threadless at once shows the user whether delivery is possible on the basis of location. Dropbox shows different upload instructions depending on the user’s browser. In a game Kingdom Hearts on PlayStation2 characters can discuss another game you’ve played as they see other game savings on the device.
Interface should gather information and adapt itself. For example, in “alarm clock” app: if a user hasn’t used Snooze button, it’ll delete it from interface or will offer a user time, if he has used it 3 times already.
Dan Saffer’s book “Microinteractions: Designing with Details” is available on Amazon.