Teens are less likely to use alcohol, tobacco or other substances when their parents are monitoring their activities, according to a new study.

Researchers found parents did not actually have to catch their teens using substances and punish them in order to deter them, HealthDay reports. Simply being aware that their parents were monitoring their behavior reduced teens’ use of substances by 40%. The findings come from a survey of more than 4,500 11- to 15-year-olds from communities across the U.S.

“Some parents think drinking or using drugs is something that kids are just going to do, no matter what,” researcher William Pelham of the University of California-San Diego said in a news release. “But that’s not true. Parents can make a difference.”

Previous studies have found that teens are less likely to use substances when they have parents who monitor their activities. The assumption has been that monitoring works because parents are more likely to catch teens using substances and punish them for it, Pelham said. The new study suggests that monitoring teens can reduce their chances of using substances simply by making them think twice, whether or not their parents actually catch them.