Notification display time

Question

What is the "thumbs up" duration time for displaying notification?

Context: mobile app which is a client for the REST web service. I'd like to show error notification for cases when connection is interrupted, user goes offline or received data is "damaged".

Would the permanent, user-dismissable error would be better in this case? My colleague argues that for temporary notification shown for a few (2?) seconds user may be looking away and miss the notification altogether. My stand in this case is that we can't solve user's attention span problems.

What are your takes on this topic?

update

From user's POV the error would simply be something along the lines of "We could not load your selected section of the catalog". I'm not going to show any technical information at all. It'd be along the lines of (as stated in Anna's answer) "no internet connection" or "unable to list items in your selected category".

Answer 1

Could you please provide more details about which types off errors you are addressing?

If the error is critical and the user cannot use the system partially/completely than the user would need to know what happened and how to address the problem to use the system normally. If the error is shown and than it disappears, the user has no way to act. Try not to think "we can't solve user's attention span problems". Try to think "what can I do to keep my users happy" :). Ideally your system never goes into "damaged" data state, of course, that can be challenging. So perhaps you can think of ways how the system can continue operate normally with the least damage to user experience.

If the error is temporary and the system can recover without user involvement then the user might not even need to know. Another question is whether the user can use part of the system having the error. If yes, then you can let user interact with the system but still provide an ability to come back to the "error" that effects the system to be able to resolve it (in your case looks like it's corrupt data issue which might get resolved if the user simply tries later). I would also recommend not using any technical jargon when describing the problem (e.g. damaged data, REST server problem...). Instead, the message should describe the situation that anyone can understand (e.g. No internet connection, unable to get pictures, please try again).