California Senator Dianne Feinstein recently declared war on homemade soap in order to placate her corporate donors, so it is no surprise the public holds her in rather poor regard. Yet it is not just her, U.S. Congress approval ratings are at record lows across the board and a new study speculates that this may be partly due to a decline in the use of warm, agreeable language in the House.

The analysis found that the use of prosocial words -- language such as cooperate or contribute -- by lawmakers predicts public approval of Congress six months later.

The results were derived from a textual analysis of 124 million words spoken in the U.S. House of Representatives between 1996 and 2014, using a computer model that searched for words validated as having prosocial connotations. The words whose decline most strongly predicted a decline in public approval were gentle, involve, educate, contribute, concerned, give, tolerate, trust and cooperate.

Congress's approval rating has slumped precipitously since 2002, when public regard was reliably over 50 percent - bipartisan support got the President education reform, funding for human embryonic stem cell research for the first time and an invasion of Afghanistan and people were happy things were getting done, even if those issues fell down on predictable party lines. Recent polls cite ratings as low as only 10 percent and a war on small businesswomen who make their own soap is not helping.

But it may be the language that is also hurting. A Senator lauding the support of industry-funded trade groups and chemical corporations while declaring homemade soap a medical device that needs to a special tax uses scary language about formaldehyde and lead and after controlling for the unemployment rate, and governance factors such as the number of bills passed and presidential vetoes. They found that warm, prosocial language - or negative anti-social language designed to scare people - was the strongest single predictor of public sentiment.

The authors suggest the media may be playing a role in this relationship. 

Citation: Jeremy A. Frimer, Karl Aquino, Jochen E. Gebauer, Luke (Lei) Zhu, Harrison Oakes, 
'A decline in prosocial language helps explain public disapproval of the US Congress',  
PNAS May 11, 2015 doi:10.1073/pnas.1500355112