A new report suggests that students at two-year institutions learn more slowly than those in four-year programs because higher education exacts greater financial and psychic costs from people in community colleges.

The report, “The Other College: Retention and Completion Rates Among Two-Year College Students,” acknowledges that student characteristics like family income and academic preparation explain some of the differences in the rates at which two- and four-year students stay in college and graduate on time. But those characteristics don’t completely explain the gap, and the authors hypothesize that differences in relative costs might.

For example, community-college students may struggle more with college-level work, causing college to exact a greater psychic cost from them. Two-year students, particularly if they are attending a community college less than half-time, also tend to have more limited access to financial aid than their counterparts in four-year programs.

The authors — Molly F. McIntosh, an analyst at the nonprofit CNA, and Cecilia E. Rouse, an economics professor at Princeton University — conclude that more research is needed to test the theory and possible policy solutions. They call for an appropriation of federal money to do so, and Ms. Rouse may have the ear of President Obama, who recently named her to his Council of Economic Advisers. —Elyse Ashburn