I love getting my Monday-morning Alertbox fix from Jakob Nielsen. This morning’s piece talks about a little-discussed usability problem: when user interfaces are too fast. (But note that Nielsen points out that 99% of response time problems are still caused by the UI being too slow.)
Two key problem areas when it comes to too-fast content:
Pulldown lists that are too dynamic, refreshing so quickly that new list elements suddenly appear just when the user is about to click on another list element. Nielsen describes an instance in which a usability test subject repeatedly clicked on the wrong item because the list changed in a fraction of a second, but the change wasn’t visible because the tester was already hovering over the item.
Carousels, rotators, and other autoforwarding design elements that change so rapidly that they’re yanked off screen before you’re able to decide if the content is useful to you or not. This usability problem is annoying for anyone, but seniors, children, and international customers are most affected.
Six things you can do to deal with too-fast UI problems:
- If possible, confine rapid page updates to user-initiated actions. This way, users know to expect changes.
- Ensure that the update is visible close to wherever on screen the user initiated the action. If the update happens too far away from wherever the user is focusing, it’s much more likely to go unnoticed.
- Slow down the change. Nielsen suggests, as an example, signalling change by using an animation that lasts a second or so.
- Some people suggest that you forgo design elements like carousels and sliders entirely.
- If you do need to use carousels, etc., a general rule of thumb is to have each slide pause for between 8 to 12 seconds, depending on how much information it contains. (Another way to calculate transition time is to clock how long it takes you to read aloud the copy on a slide, then multiply that time by 2.5.)
- If your page uses carousels or similar elements, be sure to pause the transition when the user hovers over the banner.
Do you have any other usability tips for when content is too fast? Let me know in the comments.