Melanie Mason at LAT:

It’s not your imagination. Political discourse on Twitter really has grown meaner in recent years, according to a new study.

The research, published Thursday in the journal Social Psychological and Personality Science, found that the level of incivility in tweets by members of Congress increased by 23% between 2009 and 2019 — a change the study’s authors attribute in part to how Twitter’s “like” and “retweet” buttons reinforce the spread of toxic content.

Its findings mark “the first robust evidence that incivility is rising among American politicians on Twitter,” wrote the study’s authors, hailing from several U.S. and Canadian universities.

Researchers examined 1.3 million tweets from official congressional accounts between 2009 and 2019. To quantify the levels of incivility, they used artificial intelligence to analyze the messages and assign a toxicity score from 0 to 100, reflecting the likelihood that someone would consider the text to be rude or disrespectful.

The analysis classified a 2009 tweet by then-Sen. Arlen Specter (D-Pa.) with a high incivility score of 45.1 for accusing a rival of “going AWOL” from his congressional post. And a 2019 tweet by Rep. Kevin Hern (R-Okla.) — which said another politician was “endorsing infanticide & proudly doing it!” — scored at 47.6.