How long can a user remember what they were working on?

Question

A web application lets the user browse its screens for future or past months. The time period the user is currently viewing follows the user through every screen of the system. But users can be logged in for a month or more. After a certain period of inactivity, we will prompt the user:

You were viewing November 2008 when you last clicked. Want to view the current (default) time period instead?

How long between user clicks should we wait to show this message? I'm guessing somewhere between 30 minutes and 3 hours most people will forget what they were doing, but I'd love to have some data, or someone's experience to base it on.

Other suggestions related to this issue?

Answer 1

If this is an application people will use more than twice in any given (short time period x 2) without changing these notifications will become extremely annoying. It's easy to think little reminders are helpful, but in reality unless they are very rare and only for significant events, they're just plain annoying. Remember Clippy? Never forget Clippy; "helpful" turns into "I HATE THAT $#%^ING PAPERCLIP" in only a couple of failed attempts at "helpful" actions.

Additionally, short term memory's temporal length is not well defined and varies significantly (from 30 seconds to 24 hours depending on situation and definition). Whether you remember depends very very much on whether you focus on/repeat/generally try to remember whatever information is in short term memory. And a switch back to the context may immediately jar "lost" memory--or it may not. You can't depend on timing here.

So instead of using a notification and/or basing this on how long they've been away from the computer, make it easy to find contextual information. Leave the current working context clearly labeled in the same place on each page, and make it easy to get back to the "default" view (if it's a common action) like this:

^{download bmml source – Wireframes created with Balsamiq Mockups}

Or this:

^{download bmml source}

A simple navigational element like a bar at the top of the screen can provide all the information you need to keep your place (and you don't always have to be idle for 30 minutes to forget where you are). Windows Explorer is a great example of this:

I get back to my computer, I can easily see where I left off. There's no chance your timing is off, since the element is always there; you don't need to guess at when I'll have forgotten the context. And perhaps even more importantly, the navigational aspect means it's useful even if I haven't forgotten what time I'm in, maybe I just want to go back to select a different time/directory/context.

Answer 2

"I'd love to have some data" good, so don't forget the instrumentation when you put this together. I think it's safe to assume after 30 minutes they were doing something else and should not be put out by having the message, moreover it may enhance usability when your users see the message it can create a sense that the system is still there. When someone leaves a screen to do something else and comes back to it looking identically, they may feel it died due to lack of attention. A message will however give them a sense that it knew they weren't paying attention, and is now ready for them to interact with it again.

Answer 3

Assume the shortest possible attention span.

Popups are fine, but there should be some easy way to bring them back on the screen if they are relevant very long after you first flash them to the user.

A more effective method might be to show this data on a status bar or fly out.

For some heavy multitaskers, 30 minutes will be too long.