Researchers aiming to quantify global happiness on social media have called the period starting on 26 May “the saddest two weeks” on Twitter.

Chris Danforth and Peter Dodds, applied mathematicians at the University of Vermont in Burlington, have been tracking public sentiment on Twitter since late 2008 using the ‘ h edonometer ’, a tool that looks at the words in a randomly sampled 10% of tweets each day and rates them according to how positive or negative they are. In mid-March, as the COVID-19 pandemic swept across the Western Hemisphere, the tool charted a deep, sustained dip in the global mood. Then, the worldwide protests following the killing of George Floyd in May set off a second wave of negative sentiment on the platform unlike anything Danforth and Dodds have ever seen (see ‘The many moods of Twitter’).

The hedonometer compares the language used in tweets to a database of more than 10,000 common words, culled from Google Books, The New York Times , music lyrics and Twitter itself, that have been scored by 50 people on a 9-point scale; neutral words and those which receive a large range of scores are excluded from the analysis.

Certain events — such as mass shootings, announcements of controversial government policies and deaths of well-known figures — show up in the hedonometer as one- or two-day dips. But typically, these are quickly drowned out by the background noise related to music, sports and celebrities, Danforth says. But with pandemic-associated lockdowns a major focus of people's time and attention, it makes sense for the signals of sadness to be prolonged.

Although Danforth and Dodds were quick to declare this milestone in unhappiness, other researchers are more reserved in their judgement. “Surely this is a very sad week,” says Munmun De Choudhury, a computer scientist at the Georgia Institute of Technology in Atlanta. But the changing demographics of Twitter users over time — as well as the changing ways that people use Twitter — make it hard to say for sure whether it has been the platform’s saddest.

And sorrow alone doesn’t tell the whole story, says Desmond Patton, a social scientist at Columbia University in New York City. “It’s one thing to tell the world ‘this is the saddest week’,” he says. “But also in the saddest week, you have thousands and thousands of people who are now activated and moving towards equality and social justice.”

This mobilization, too, is captured in the hedonometer, Danforth says — the tweet volume over the past 2 weeks is nearly double the daily average from 2019. The strength and the duration of the signal are unique to this moment, he says. “Both the pandemic and these protests have been far more cohesive in terms of collective attention than anything we’ve ever seen.”