It may come as a shock to disillusioned middle school teachers, but the brains of adolescents are better suited to learning than those of adults. Areas of our brain that assist with some types of learning at least to the age of 17 subsequently lose this capacity.
Teenage brains are more sensitive to rewards than those of their elders, something that leads to a lot of hand-wringing about susceptibility to short-term thinking and the allure of drugs. Harvard University's Dr Juliet Davidow sees things differently. “The adolescent brain is adapted, not broken,” she said in a statement. “The imbalances in the maturing teenage brain that make it more sensitive to reward have a purpose – they enable adolescents to be better at learning from their experiences.”
Davidow had 41 teens aged 13 to 17 and 31 adults in their 20s play a learning game. The majority were scanned using a functional MRI (fMRI) machine while playing.
The game required players to guess which flower image the butterflies would land on. The first guesses were pure chance, but over time players saw patterns emerge. Unrelated images accompanied the words telling players if a particular prediction was correct. Subsequently, the players were tested on their memories of these images. Satisfaction aside, there were no prizes for right answers.
Teens outperformed adults on both aspects of the test, Davidow reported in Neuron. They picked up patterns of which butterflies preferred particular flowers more quickly and also had a better memory for the unexpected objects that appeared with the assessments to their answers.
Some of the images seen by game players in Davidow's experiment. Davidow et al/Neuron
The difference in performance is not a matter of brain capacity starting to decline at 20. Instead, the fMRI scans revealed teenagers were using two brain regions, the striatum and the hippocampus, during the learning task, something that has not been reported previously. The adults largely relied on the striatum alone.
The hippocampus was not just coming along for the ride in this process – the more it was used, the more likely the teenagers were to remember the images they had been shown. The limited workout the adults' hippocampus got didn't show any relationship with learning. Davidow and her co-authors link the teenage performance to the reward-seeking behavior that is usually portrayed as destructive. Along with being important for long-term memory, the hippocampus has known associations with motivation and other reward-related behaviors.
“As adolescents navigate through new life experiences, learning from reinforcement is linked to how episodic memories are shaped and to the extent to which they are biased toward encoding more of the good than the bad,” the paper argues.
The adolescents didn't outperform adults on all forms of learning, and Davidow is keen to extend the research to discover what engages the teen hippocampus. She thinks the answers could assist teachers in making their classes connect with students' hippocampuses, increasing the chances knowledge will stick.
A comparison of the brain regions lit up during the test in Adolescents (A), Adults (B) and the statistically significant difference in the left hippocampus. Davidow et al/Neuron