Singaporean who are younger, better educated, have higher incomes, and live in a more expensive house are more likely to have a close friend from another race.
The findings, from an Institute of Policy Studies (IPS) and OnePeople.sg survey released on Thursday, goes against some commonly held perceptions that older folk, and those living in Housing Board flats, have deeper relationships with those from other communities.
Tertiary schools and cosmopolitan workplaces may give the young more opportunities to build such friendships, said Dr Mathew Mathews, the study's principal investigator.
Education and working together tend to "open people's world view and help people become more apt at dealing with diversity", said the IPS research fellow.
Race differences may also become less salient as people become better off, he added, as their values and aspirations tend to be more similar to one another's.
In the study, more than one in two of the 4,131 Singaporeans surveyed said they did not have at least one close friend of another race. The overall profile of the survey's respondents mirrored national demographics.
About two in 10 Chinese had a Malay or Indian friend, while nearly two-thirds of minorities had at least one close Chinese friend.
The study defined a close friend as someone with whom they felt at ease, could talk to about what was on their mind, or they could call on for help.
Across all the three major races, those aged between 18 and 25 were more likely to have such friends from another race than those who were older (see table).
Among those surprised by the findings was Inter-Racial and Religious Confidence Circle leader Ameerali Abdeali, who said he had expected older people to be the ones more likely to have close cross-racial friendships.
Because of his childhood in a kampung, he has close friends from other races, he added.
But rosy pictures of interracial camaraderie that were a result of kampung days might not be representative, said Dr Mathews, noting that some of these communities were segregated.
Moreover, these ties might not have translated to close friendships, on which the study focuses, said OnePeople.sg chairman Zainudin Nordin.
Dr Mathews added: "Speaking a common language didn't necessarily mean people were deeply connected (to those from another race). The racial riots happened in the 1960s, a time when people did speak other languages."
Experts also noted that the recent increase in interracial marriages among the young complement the findings.
"That's the epitome of integration," said sociologist Paulin Straughan, who was not involved in the study.
The strength of interracial ties was also greater the higher up the socioeconomic ladder a respondent was, the study found.
"People from similar class backgrounds share similar values and lifestyles, and cross-racial friendship becomes a lot more possible," Dr Mathews said.
"The higher you move up the socioeconomic ladder, towards the middle class and beyond, the more people's values become similar. There's more likelihood of you finding affinity and closeness with others with similar values, regardless of race."
Commenting on the finding that those who pursued higher education were more likely to have close friends from another race, Prof Straughan said polytechnics and universities were much less homogeneous than primary and secondary schools.
"At those levels, there's a higher likelihood that you're in a Chinese-medium school or mission school," she said.
She pointed to how there tend to be fewer Muslims in mission schools, and fewer Indians and Malays in Special Assistance Plan schools, which have a focus on Chinese culture.
"But by the time you come to polytechnics and universities, the boundaries are broken down. There's more ethnic diversity, and a greater likelihood you'll mix with those not from your race," she said.
How can interracial ties be strengthened, especially among the lower-income groups?
Mr Zainudin, an MP for Bishan-Toa Payoh GRC, suggested small-group recreational programmes to help neighbours get to know one another better.
This could take the form of encouraging them to greet one another in lifts, and fun quizzes about how well they knew one another.
"This allows people to get a bit of courage to say hello," he said.
But at the end of the day, he added, it was still down to the individual to make a move.