Trying Teens

Assessing Risk Assessment

The prefrontal region of the brain helps to manage reasoning, impulse control and judgment—traits that would help prevent someone from committing murder. Brain imaging studies that tracked subjects from ages 4 to 21 found that the prefrontal cortex is one of the last brain areas to fully develop.

But if an immature prefrontal cortex accounts for adolescent behavior, children should take even more risks than teens. Instead, risk-taking behavior peaks during adolescence. So other neurological factors must be at play.

To account for risky behavior, science looks to the brain’s limbic system. Located in both hemispheres, it affects what BJ Casey, director of Cornell University’s Sackler Institute for Developmental Psychobiology in New York City, refers to as “desire, fight and flight.”

She provides a model that accounts for teens’ willingness to drive while drunk, have sex without a condom and take a gun to school and shoot a classmate. While impulse control improves linearly with age as the prefrontal cortex develops, the limbic system matures around puberty. So humans may be most prone to risky behavior during adolescence, until the prefrontal cortex catches up. Though most teens have not had their mug shot taken before the high school prom, their parents, teachers and coaches can attest to their emotionally-driven behavior. “In terms of emotional reactivity, it does appear to be enhanced during the teen years,” says Casey.

Impulsive and risky adolescent behavior may actually be a welcome trait from an evolutionary perspective, Casey points out. Leaving the family as a teenager was necessary to find a mate. And following sex drives allows for procreation and the passing on of genes.

But this hereditary process may have handicapped Brandon in light of his parents’ genes and their emotionally-driven behavior, detailed in local newspaper articles this spring. He frequently witnessed his parents fighting during his first few years. And by age 6, they had separated. Custody changed between his parents several times, with some agreements conditioned on their refraining from drug or alcohol use in his presence. His father pled no contest to a domestic battery charge against Brandon’s mother in 2000. Yet according to court records, Brandon’s father claimed that his wife pursued Brandon and him in a car chase, nearly forcing them into oncoming traffic. Recognizing these first-hand experiences of violence in Brandon’s family and the enhanced emotional state apparent in many teens, Casey calls Brandon’s formative years “a double whammy for this child.”

Science Applied

Opinion at E.O. Green Junior High, Brandon and Larry’s school, partially reflects what science has revealed about adolescent thought and behavior. Half the faculty and 130 of the 1100 students there signed separate petitions asking the district attorney to transfer Brandon’s case to juvenile court. In addition, 27 lesbian, gay and other civil rights organizations collectively released a statement on April 14 that said, in part, “We refuse to let our sense of outrage blind us to the fact that the suspect is only 14 years old.”

This public plea cannot determine innocence or guilt in court, but it could become a factor during sentencing. Quest, Brandon’s lawyer, could argue that because of his age, this teenager should not suffer the same punishment as an adult who committed first degree murder. After all, had this murder occurred less than three weeks earlier, this debate would be moot. California district attorneys can charge children 14 or older as adults without petitioning a juvenile judge. But Brandon turned 14 on January 24—less than three weeks before killing Larry.

Bennett, the developmental cognitive scientist from the University of California at Santa Barbara, does not believe that science should make a black-and-white blanket determination of what age is appropriate for a defendant to be considered an adult. “It’s never black and white for us,” says Bennett, speaking as a scientist. “But what we do know is that it takes much longer to become an adult than many of us originally thought.”

Stephen Morse, a professor of law and psychiatry at the University of Pennsylvania and an expert in criminal and mental health law, also recognizes science’s current limits. “All science can show us is the average differing capacities of adults and adolescents,” he says. “But whether that is enough to change the law is a legal question.”

Related on Scienceline:

Do video games make teens more aggressive?

Find out how children develop language.

Teens, alcohol and the law.