A poll conducted last fall and released Monday reveals widespread unfamiliarity with the healthcare law before enrollment began on Oct. 1.
The survey, published in the Proceedings of the National Academy of Sciences, underscores the serious challenge that faced the Obama administration as it began to promote ObamaCare to the public.
Familiarity with the exchanges was even smaller among the uninsured, with only about one in three professing to know about the new system one month before its rollout.
An equal share of the uninsured were unaware of ObamaCare's income-based subsidies to make coverage more affordable. A slight majority (52 percent) said they knew about the penalty for going with coverage, which kicks in starting April 1.
Citing their results, study authors wrote that "a substantial share of the population is unprepared to navigate the new exchanges."
"Particularly worrisome is the lack of understanding among lower income families," the authors wrote. "This group is ineligible for Medicaid and could benefit from the exchanges. They appear at high risk of making poor decisions when shopping for health insurance."
The age of the survey makes it difficult to say whether the figures remain true or relevant to enrollment under ObamaCare.
The administration's efforts to educate the public are reaching their peak this month, six months after respondents answered the survey questions.
But queries related to health insurance in general likely have more staying power, and they suggest that federal health officials are trying to reach a public that's confused about the basics of health coverage.
Over 40 percent could not describe an insurance deductible, the amount of money someone must pay out of pocket for coverage before an insurer pays any expenses. This figure was even higher — roughly three in five — among the uninsured.
The survey reflects responses from 3,414 people.