A newly released survey shows that Americans who care about expert opinion and scientific evidence hold different policy positions than those who don’t — across party lines.

The survey, conducted in January by the independent research organization NORC at the University of Chicago and released Tuesday, asked 1,007 Americans online and by phone about how they seek out and process information. About four in five respondents said that it is easier now than it was five years ago to find useful information, but four in five also said that they are sometimes or often overwhelmed by how much information comes to them.

Sifting through so much information, Americans have to decide which pieces are valuable to them. When they do, some place a much higher value than others do on information that comes from sources referring to experts or scientific evidence, or that is based on government data. And the more people value those kinds of information, the more they are likely to support Obamacare and same-sex marriage and to believe global warming is happening.

The effect persisted after controlling for demographic characteristics and for political party affiliation. So, for instance, 39 percent of Republicans who think information related to experts is important agree that “homosexual couples should have the right to marry one another,” compared with just 9 percent of Republicans who don’t.

The study doesn’t tell us whether holding certain policy beliefs makes people more likely to place a premium on expertise or data, or the other way around — or whether some other trait determines both policy beliefs and prizing evidence. “Causality is difficult,” said Norman Bradburn, a senior fellow at NORC and the senior adviser on the report. “You can’t infer it.”

NORC conducted the poll in January to try to avoid a time when respondents would be overly influenced by the presidential campaign in full swing, Bradburn said, even while planning to release it around NORC’s 75th anniversary this month. Researchers sought to choose issues that were sufficiently controversial and likely to remain relevant throughout the campaign. “Most people don’t have an opinion on most issues except those right at the top of public discussion,” Bradburn said.

The study covers much more than policy positions. Bradburn said that with so many alternative sources of information available to respondents, he was particularly struck by the high level of confidence they still place in newspapers: 90 percent of Americans who use them, in print or digital form, said they “can completely or mostly trust” newspapers as a source. The decline of local papers might have taken a toll, though: Only about half of Americans say they are more informed about local news and civic life and government activities in their communities than they were five years ago.