After Brazil’s 2018 presidential election, international political pundits and journalists wondered if social media platform WhatsApp enabled far-right candidate Jair Bolsonaro’s rise to power. Northwestern University computer scientists now confirm that WhatsApp use played a key role in the electoral process.

After performing the first large-scale analysis of partisan WhatsApp groups in the context of Brazil’s 2018 election, the researchers found that right-wing users were more effective in using the social media tool to spread news, disinformation and opinions.

More specifically, right-wing groups in Brazil were much more numerous and shared substantially more multimedia content and YouTube videos than left-wing groups.

“Our ultimate goal is to understand how information and misinformation spreads, so we can find technological interventions,” said Larry Birnbaum, the study’s senior author. “We want to find ways to help people better evaluate the information they receive. Media literacy has not caught up with rapid changes in technology.”

Victor Bursztyn, the paper’s first author and a doctoral student in computer science at Northwestern, will present their findings at 11 a.m. EDT on Friday, Aug. 30, at the IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining in Vancouver. Their paper is titled “Thousands of small, constant rallies: A large-scale analysis of partisan WhatsApp groups.”

With more than 120 million users, Brazil is the second-largest WhatsApp market in the world, trailing India. While Americans tend to use WhatsApp for one-to-one or small group text messaging, Brazilians use WhatsApp for most everything: text messaging, large group chats, and sending and receiving news. WhatsApp allows users to join public and private groups with up to 256 members to share text and multimedia messages, transforming chat groups into highly active social spaces.

2.8 millionpartisan messages analyzed

“More than half of Brazil’s population uses WhatsApp,” Bursztyn said. “WhatsApp’s large groups are often targeted for political outcomes.”

From Sept. 1 to Nov. 1, 2018, Birnbaum and Bursztyn followed 232 partisan groups. During that time, they collected 2.8 million messages from more than 45,000 users. (This is 3.5 times as many messages and 2.4 times as many users than the largest competing dataset to date.)

The team discovered multiple differences between right- and left-wing groups. In the studied sample, right-wing groups shared 5.5 times as many messages as left-wing users. Of the messages shared by right-wing users, 46.5% were multimedia messages, such as photos, audio and video files. Just 30% of left-wing messages included multimedia.

“It’s hard to say whether multimedia is more effective in influencing opinions, but right-wingers are more savvy in using them,” said Birnbaum, professor of computer science in Northwestern’s McCormick School of Engineering. “Images are always more compelling than text.”

Birnbaum and Bursztyn also found that the most-shared news by WhatsApp groups during the 2018 presidential election campaign came from websites that spread disinformation, as identified by several fact-checking agencies. Right-wing groups tended to spread disinformation from four popular, skewed sites. Left-wing groups shared news from one popular, skewed site.

“Data suggests that both sides consume this content, but it’s a more prevalent problem on the right,” Birnbaum said.