Teenagers act more mature when mothers are presentNew York, April 24 (AZINS) Teenagers are less likely to indulge in risky behaviour such as jumping a traffic signal when moms are around, finds a study.

In the study, 14-year-old subjects completed a simulated driving task while researchers tracked blood flow in their brains.

"In one trial, the teenage driver was alone. In another, the teen's mother was present and watching," said University of Illinois psychology professor Eva Telzer who led the research.

Telzer and her colleagues observed that teenagers driving alone found risky decisions rewarding.

Blood flow to the ventral striatum, a "reward centre" in the brain, increased significantly when teen drivers chose to ignore a yellow stoplight and drove through the intersection anyway.

Previous research has demonstrated that the ventral striatum is more sensitive to rewards in adolescence than during any other developmental period, Telzer said.

"Peers significantly increase risk-taking among teenagers. I wanted to know whether we could reduce risk-taking by bringing a parent into the car," Telzer said.

The mother's presence blunted the thrill of running the yellow light, the team found.

"When mom is there, the heightened ventral striatum activation during risky decisions goes away. Being risky, it appears, is no longer rewarding in the presence of mom," Telzer noted.

Not surprisingly, teenagers stepped on the brakes significantly more often at yellow lights when their moms were present than when they were alone.

Another brain region, the prefrontal cortex, kicked into gear when teenagers put on the brakes -- but only when their mom was watching, the researchers found.

"A parent's presence is actually changing the way the adolescent is reasoning and thinking about risk -- and this increases their safe behaviour," she concluded.

The study appeared in the journal Social Cognitive and Affective Neuroscience.