Research suggests that the emotions shared in friends' Facebook posts have a real, measurable effect on the sentiment of our own status messages. The following interactive applies a scientific measure of sentiment to your friends' posts to see whose updates are boosting your mood the most.
To determine your top friends, this tool takes into account mutual friends, who you appear with in photos, and whose posts you've frequently liked. Then it analyzes the posting behavior of the top 25 people on this list, discarding anyone who has written fewer than 10 status updates in the past year or whose privacy settings hide their posts from apps.
To measure the positivity and negativity of Facebook posts, this app uses the same method as the researchers who first announced the effect of emotional contagion on Facebook in March. For any given status, it compares each word in that status to a list of hundreds of positive words, like “hilarious” and “thoughtful”, and hundreds of negatives words, like “disaster” and “pathetic.” While it is blind to context and does not understand sarcasm, this method has been empirically shown to correlate to the emotional content of a written message. (This system, known as Linguistic Inquiry and Word Count, is a technology pioneered by a researcher at the University of Texas. TIME is using it with permission.)
Over large numbers of posts, researchers found familiar patterns in the data that this measurement produced. The rate of positive posts is considerably higher on weekends. Moods spike around holidays in both positive and negative directions and reliably dip when it is raining (something the researchers measured by comparing the location of users and the timestamps of their posts to local weather data).
Of course, since the system is based on words, it misses one important emotional activity when applied to Facebook. It doesn't notice when you like others' posts.