And the problems go beyond awareness of the exchanges. "Many people lack a basic understanding of how health insurance works," Barcellos said.
March 31 is the deadline for enrolling for insurance coverage for 2014 under the Affordable Care Act.
Of all survey respondents, 42 percent did not know what an insurance deductible was -- including 58 percent of the uninsured.
The same was true for 30 percent to 45 percent of those living between 100 percent and 400 percent of the federal poverty level. Many of those Americans are eligible for tax credits to help pay for insurance bought through the exchanges. They are another group that stands to benefit the most from the Affordable Care Act.
But if uninsured and lower-income people don't understand how health insurance works, Barcellos said, "how can you expect them to make informed decisions when they choose a plan?"
Sharon Long, of the Urban Institute's Health Policy Center in Washington, D.C., agreed.
"Health insurance is complicated, and we're talking about people who may never have had it in the past," said Long, who was not involved in the study. "It's ironic that we're asking people without that experience to make good choices."
Brookings' Patel pointed out that this problem was anticipated. Federal and state governments have so-called navigator programs to help applicants get through the enrollment process. Those navigators include individuals and groups -- from nonprofits to hospitals to church groups -- who are trained and certified (and paid) by the government.
"The role of the navigators is important," study author Barcellos said. But, she added, people also need to know the programs exist.
There are other potential ways to make the exchanges more user-friendly, according to Barcellos. One step, she said, could be to redesign the exchange websites to "nudge" people to the best plans -- by highlighting certain economical and better-quality plans on the first page of the site.
Barcellos said research has shown that when people have too many choices -- especially complex ones -- their tendency is to opt for whatever seems easiest.
"Or," she said, "they may make no choice at all."