SINGAPORE - The mentally draining task of faking one's emotions to adhere to certain workplace policies, such as giving customers "service with a smile", can make supervisors more abusive to their subordinates, according to research by the National University of Singapore (NUS).

The study by Dr Sam Yam, assistant professor of management and organisation at NUS Business School, involved surveying 184 employees and their supervisors working in customer service and sales in the United States.

The survey found that supervisors who reported doing more "surface acting", such as faking a good mood or suppressing anger in front of customers, were about 1.34 times more likely to be abusive towards their staff, because such acting deprived these bosses of the mental resources to rein in abusive behaviour.

The study required supervisors to respond to statements such as "I faked a good mood in front of customers", "In general, I am good at resisting temptation" and "I feel like my willpower is gone".

Their staff were also required to rate their leaders' supervisory behaviour over three weeks.

The survey was aimed at assessing how often supervisors engaged in "surface acting", how much mental self-control they had, and whether their staff viewed them as abusive leaders.

"Our findings are significant because they open the door to more intervention options," said Dr Yam. "For instance, service organisations might want to reconsider how they encourage their staff to provide good service."

"While forcing employees to smile and suppress other emotions might help a company's image, such practices also risk compromising supervisor-staff relationships in the long run," he said.

Not surprisingly, it found that supervisors who had a higher degree of self-control as a personality trait were less likely (by about 14 per cent) to become abusive from surface acting.

Said Dr Yam: "Our research suggests that abusive supervision can be mitigated by replenishing the supervisors' mental resources and hence, their resources for self-control."

"For instance, organisations can help employees regain their self-control resources by encouraging them to take short breaks at work. Likewise, self-affirmation training can enable individuals to replenish depleted resources."

Dr Yam's research will be published in a forthcoming 2016 issue of the Journal of Applied Psychology.