Students from poorer families are more likely to be deterred from university by tuition fee debt, researchers say.
A study by the UCL Institute of Education compared attitudes of people considering applying to university in England in 2002 and 2015.
During this time tuition fees increased from about £1,100 per year to £9,000.
Researchers found that young people in general had become accustomed to higher fees – but worries about debt levels had risen among low-income families.
Tuition fees have become a battleground in the general election.
Labour has promised to scrap tuition fees in England – while the Conservatives and the Liberal Democrats would continue with a system of fees and loans.
Researchers from the Centre for Research on Learning and Life Chances, based at the institute in London, examined the results of two surveys of potential university applicants either side of significant increases in fees.
Young people in the 2015 survey had become more ready to accept student debt, seeing it as a necessary part of getting a degree.
Women, in particular, were ready to believe that borrowing to go to university was a good investment.
But the study says there were different attitudes among low-income families, who were more resistant to debt in 2002 than their wealthier counterparts.
And the study says that these levels of debt aversion among poorer families were even greater in 2015.
Youngsters from the “squeezed” middle class also appeared more concerned about debt, says the study.
Despite the increase in cost, university applications continued to rise across these years – and there are higher numbers of students from all backgrounds, including from poorer families, now getting places.
But one of the researchers, Prof Claire Callender, said there were still significant differences in application levels depending on young people’s backgrounds.
Much of the difference has been attributed to exam results in school, with wealthier students more likely to have got the results needed for university entry.
Prof Callender says that this “disguises a more complex picture”.
“Working-class young people are far more likely than students from other social classes to avoid applying to university because of debt fears,” she said.
She said that even when poorer youngsters had the same exam results, they were less likely to apply to university than wealthier ones.
“Student funding and fear of debt play a role. University enrolments may be increasing overall but policymakers must focus on ways to level the playing field for poorer students,” said Prof Callender.
But Universities UK, representing university leaders, defended the value of the fee system and said “those from disadvantaged backgrounds were more likely to enter university than ever before”.
“It is important to remember that it is high-earning graduates who benefit the most from a policy of no fees – under tuition fees they would repay their entire student loans.
“Removing fees benefits those who go on to earn the most, while having little or no impact on lower earners,” said a Universities UK spokeswoman.