In the context of a web app, which makes for a better User Experience: using copy that states the facts as simply as possible or copy that speaks in casual language, yet could end up being more wordy?
Here are 3 examples as the answer may be different depending on the situation:
Short and Simple: OPEN
Casual: OPEN your document
Short and Simple: Error: Unable to send. TRY AGAIN
Casual: Oops! We were unable to send your message. Would you like to TRY AGAIN?
Short and Simple: CANCEL, SAVE, CLOSE
Casual: Would you like to SAVE this first or CLOSE without saving? Nevermind, take me BACK.
I gave 3 examples, but there are others. Short and simple is nice and to the point, but casual language can help users understand and gain clarity with the small penalty of possibly being more wordy.
Is casual text better most of the time?
When should you use one way over the other?
Are there any studies that have been conducted on this subject?