At the age of 18, more than 30 years ago, he joined the police force, attending to numerous cases such as domestic abuse and fights between gangsters.
Today, Professor David Chan rubs shoulders with very different sorts, and moves in circles that saw him become in August the first scientist to be made a fellow in all six international associations of psychology.
While his early and current careers might appear worlds apart, the 52-year-old psychologist at the Singapore Management University (SMU) disagrees.
He lets on that his days as a police officer under the Tanglin Police Station shaped his world views and were what drove him to work on projects that can change people's lives, by shaping public policy and public actions.
"You have to deal with diverse situations and individuals, including ambassadors and 'ah bengs', and you find you have to adapt your behaviour drastically within the same day to handle the practical demands and contexts as they emerge," said Prof Chan, who was a policeman for nine years.
"That affected my values and the way I think - you have to step into the person's shoes, to see things from another's perspective; or you cannot resolve the dispute, empathise with the person, and more importantly, you cannot adapt and respond well to the demands of the situation or case."
That thinking is much in line with a current research focus: perspective-taking, which means seeing things from a point of view other than your own.
REASON FOR SCIENCE
Why are we doing science? It has to be because we want to solve human problems and enhance human well-being. It cannot be to publish in top journals and win awards. That should be the consequence of good science, not the reason for doing it.
PROFESSOR DAVID CHAN
When one does this, one is able to turn what seems like a zero-sum game into solutions which can, for instance, help to build cohesion between diverse groups such as those of different races and sexual orientation, he said.
According to social and behavioural science research, a person has several social identities, and how he thinks, feels and acts depend on which identity he activates at a point in time.
Using issues of LGBT (lesbian, gay, bisexual and transgender) people as an example, Prof Chan said: "If you and I differ in our values on sexual orientation, we will probably never agree on many basic issues of LGBT.
"But you and I can activate our common social identity - that we are Singaporeans and that we share some core values, including respecting the dignity of a human being, meritocracy and fairness, and treasuring social cohesion and harmony - that will guide us to discuss issues of LGBT.
"My social identity and yours cannot just be all about one issue, like sexual orientation. Surely we have other shared social identities like being a Singaporean that matter as much, if not more.
"But to appreciate that and use it to deal with disagreements, we must learn to see things from the perspective of others."
In his 20 years as an academic, Prof Chan has used the process of perspective-taking to shape policies, starting from his time at his alma mater, the National University of Singapore, which he joined after attaining his PhD from Michigan State University.
He left for SMU in 2005, where he set up the School of Social Sciences and now heads the Behavioural Sciences Institute. He also teaches PhD students.
He is known internationally for his research into personality and social attitudes, as well as how individuals make judgments and adapt to various changes across diverse situations.
Topics he has written about in opinion pieces include how to identify an insincere apology and finding your own meaning in life.
He said seeing his behavioural science research influence policy direction and public attitudes keeps him going, though when asked for examples, he said he was bound by confidentiality issues.
"When you can be a part of translating science to practice, to change things for the better and make a positive difference in people's lives, the effort is well worth it and a lot of good can happen," he said.
However, Prof Chan, who is single, shared his concern that the traditional reward system in academia might be encouraging social scientists to focus on doing research that quickly gets them into top scientific journals regardless of their immediate practical policy or societal value.
He added a word of caution.
"If we are not careful, we may have an academic system of reward that motivates people towards a narrow type of scholarly behaviour that gets them published in academic journals.
"But these people may not be making good use of their expertise to solve practical problems for our society.
"But why are we doing science? It has to be because we want to solve human problems and enhance human well-being. It cannot be to publish in top journals and win awards," he said.
"That should be the consequence of good science, not the reason for doing it."