How hashtags and @ symbols affect language on Twitter

When tweeters use hashtags, they tend to be more formal and drop the use of abbreviations and emoticons. But when they use the @ symbol to address smaller audiences, they're more likely to use non-standard words such as 'nah,' 'cuz' and 'smh.' When they tweet to others in the same city, they're more likely to use unique words specific to that area, a new study shows.