Twitter said yesterday it has started testing 280-character tweets, doubling the previous limit, in an effort to help users be more expressive. “Our research shows us that the character limit is a major cause of frustration for people tweeting in English,” the company said. “When people don’t have to cram their thoughts into 140 characters and actually have some to spare, we see more people Tweeting — which is awesome!” About 9% of all tweets today are exactly 140 characters, Twitter says. It’s tough to do that on accident, suggesting that users frequently have to edit their thoughts to get them under the limit. Twitter hopes to ease that burden by doubling the character limit in what it calls “languages impacted by cramming,” which includes every language except Japanese, Chinese, and Korean.