While legal and social policies typically dictate that anyone 18 or older is an adult, brain connectivity and development is still occurring into the early 20s, and can lead to lowered self-control in emotional situations, Weill Cornell Medicine investigators found in a recent study.
The findings, published Feb. 25 in Psychological Science, suggest that policymakers and members of the legal and corrections system should acknowledge cognitive development within this group of 18 to 21 year olds — as they have begun to for adolescents 13 to 17 years old — and make decisions about criminal court sentencing and punishment with developmental considerations in mind.
"It's important to understand when self-control breaks down, and to determine at what age self-control reaches adult capacity to help inform policies," said lead investigator Alexandra Cohen, a doctoral candidate in neuroscience at Weill Cornell Medicine's Sackler Institute for Developmental Psychobiology. "What we found is that in positive or neutral situations, young adults behave like their older counterparts, but that in the heat of a threatening situation, they show diminished cognitive capacity, similar to adolescents."
To reach these findings, investigators at Weill Cornell Medicine and the University of California, Los Angeles — as part of a collaboration of neuroscientists, psychologists and legal scholars, funded by the MacArthur Research Network on Law and Neuroscience — enlisted a group of 110 racially diverse 13 to 25 year olds from New York City and LA. Investigators had the participants complete what's called a Cognitive Control Under Emotion task as their brains were being scanned in a functional neuroimaging machine. Participants completed the task, during which they were shown smiling, fearful or neutral expressions.
At the start of the task, participants were also told that three scenarios, each paired with a different color background screen, could occur as they played the task. When the screen behind the faces was a certain color, the participants were told that they might randomly hear a loud and aversive sound; when the screen behind the faces was another color, they were told that they might randomly win up to $100; and when the screen was a third color, they were told that nothing would happen. Both the first and second scenario kept participants anticipating a respective negative or positive.
Alexandra Cohen, doctoral candidate in neuroscience
While young adults aged 18 to 21 performed similarly to adults aged 21 or older in neutral situations and positive situations, they performed significantly worse than adults when they anticipated a negative outcome. Their fMRI scans illustrated this result. During these negative situations, young adults showed less activity in the lateral prefrontal cortex, which is implicated in cognitive control, and increased activity in medial prefrontal circuitry, which is involved in emotional processes. These findings suggest that self-control remains vulnerable to negative emotionally charged situations into young adulthood, as prefrontal circuitry continues to develop, the investigators said.
"This study was about trying to understand why, when they know better, do young adults find themselves reacting or acting in such a strong way?" said Dr. BJ Casey, director of the Sackler Institute for Developmental Psychobiology and a professor of psychology in psychiatry at Weill Cornell Medicine. "We showed that in negative emotionally charged situations, young adults are less likely and less able to control their impulses."
In the context of the legal system, developmental considerations are important when determining sentencing and punishment, Cohen said. But this is about more than just policies.
"When young people are incarcerated, it's often not for a violent crime," Cohen continued. "Opportunities to be part of a pro-social environment during this critical period of continuing brain and cognitive development can bolster healthy development and potentially improve long-term outcomes."
"We should look at this time as a window of opportunity and obligation," Dr. Casey added. "This is about making a long-term investment in our young people, and defining medicine in the broadest sense so that we improve the overall mental and emotional health of our society."