It is well known that teenagers take risks—and when they do, they like to have company. Teens are five times likelier to be in a car accident when in a group than when driving alone, and likelier to commit a crime or drink alcohol when with a group of peers.

Now, a new study from Temple psychologists Laurence Steinberg and Jason Chein, CLA ’97, has found that an inclination toward risky behavior in groups also holds true for another teen mammal—namely, mice.

That study, “Adolescent mice, unlike adults, consume more alcohol in the presence of peers than alone,” was published in Developmental Science in November.

“Most people attribute the peer effect on adolescent risk taking to peer pressure or the desire to impress friends, but our findings challenge that assumption,” said Steinberg, professor of psychology at Temple and a leading international expert on teen behavior and risk taking. “We chose mice for this experiment because mice don’t know what their friends want them to do,” he said.

For the study, a sample of mice were raised in same-sex triads and were tested for alcohol consumption either as juveniles or as adults, with half in each age group tested alone and half tested with their agemates. The researchers found that the presence of “peers” increased alcohol consumption only among adolescent mice.

“The outcome of this study, in combination with our other recent findings involving human teens, indicates that the peer influence on reward sensitivity during late adolescence is not just a matter of peer pressure or bravado or in any way dependent on familiarity with the observer,” Steinberg said.

His previous studies have suggested that the presence of peers influences adolescent behavior by increasing the perceived reward value of risky decisions, he explained.

“We know that when one is rewarded by one thing, other rewards become more salient,” he said. “Because adolescents find socializing so rewarding, we postulate that being with friends primes the reward system and makes teens pay more attention to the potential payoffs of risky decisions.”

In a 2011 study, Steinberg and Chein looked at brain activity in adolescents, young adults and adults as they made decisions in a simulated driving game. Though adolescents and older participants behaved comparably while playing the game alone, it was only the adolescents who took a greater number of chances when they knew their friends were watching.

Another recent study published last month by Steinberg and Chein in Developmental Science showed that familiarity with the peer is not necessary for his or her presence to increase an individual’s inclination to take a risk. Steinberg found that late-adolescent participants demonstrated a significantly increased preference for smaller, immediate rewards when they believed that they were being watched by an unknown viewer of the same age and gender.

Steinberg said, “The effect that the presence of peers has on adolescents’ reward-seeking behavior may in fact be a hardwired, evolutionarily-conserved process.”