Trust is on the decline in America. Between 1972 and 2012 Americans became less trusting of and less confident in not only government and the media, but also churches, doctors, business, and each other. And, according to a new report, increasing income inequality may be to blame.

Political scientists and sociologists have long wondered how, why, and even whether trust in government and other institutions changes over time. One theory, still taught today, is that the dramatic process of entering adulthood shapes a person’s social and political traits in a lasting way. Thus, citizens born during the Great Depression tend to embrace a more frugal lifestyle and often the welfare state as well, or so the theory goes. Scholars have argued more recently that traits like being frugal or trusting government are a matter of the zeitgeist, or perhaps a matter of one’s age. Whichever is true, questions remain. If it’s the times that affects trust, what is it about a particular period that makes people more or less willing to believe what others say?

Separating out the effects of age, birth year—cohort, it’s usually called—and survey year, it became clear that trust in others and confidence in institutions declined because of the times we were and are living in.

To sort it out, psychologists Jean Twenge, Keith Campbell, and Nathan Carter looked to data from the General Social Survey, or GSS, which since the 1970s has asked a total of 37,493 Americans questions about just about everything, including a range of questions about trust and confidence in other people and groups. In the early '70s, 46 percent of Americans agreed that “most people can be trusted,” as the GSS posed the question. Between 2010 and 2012, however, those surveyed agreed with that statement just 33 percent of the time. Confidence declined by a similar amount. Only 16 percent of GSS respondents responded that they had “hardly any” confidence in the press when surveyed between 1972 and 1974, but that number nearly tripled by the 2010-12 survey.

More interesting than the raw numbers is the deeper story that the data tell. Separating out the effects of age, birth year—cohort, it’s usually called—and survey year, it became clear that trust in others and confidence in institutions declined because of the times we were and are living in. Cohort had some effects on confidence, and trust increased with age, but the data indicated something about the zeitgeist was powering the decline in trust and confidence.

That something, the team argues, is the economy. Greater income inequality, the team found, was correlated with lower trust in others, while greater poverty, more violent crime, and an improving stock market were linked with less confidence in institutions.

In an email, Carter told Pacific Standard that the team is “very interested” in how psychology and economics interact through what Depression-era economist John Maynard Keynes called “animal spirits,” spontaneous, sometimes irrational drives to economic or financial action, “which have unfortunately seen very little serious attention from either psychologists or economists."

"I really think it will take a concerted effort for collaboration across economics and psychology to get a handle on how psychological states impact economies and vice versa,” Carter says.