For a teenager's brain, the promise of a reward is a much more effective incentive than the threat of punishment: a study published in PLOS Computational Biology, which also shows how teenagers are less able than adults to reflect on the consequences of alternative decisions to those they have taken.

The test. Stefano Palminteri, an Italian neuroscientist now at the École normale supérieure in Paris, conducted the experiment while he was at University College London. He asked 18 volunteers aged 12 to 17 and 20 people between 18 and 32 to choose from a series of abstract symbols, associated from time to time with the certainty of a reward, a punishment or no consequence. During the test, the subjects learned to associate the symbol with its effect, and could modulate the choices accordingly.

The neurological mechanisms of adolescent brains

A different approach. Adults and adolescents were equally good at choosing symbols associated with reward, but teenagers turned out to be less able to avoid punishment-related symbols, or to store useful information about what would have happened if they had chosen otherwise. Computational models have confirmed behavioral data.

The study seems to suggest that positive reinforcements given by parents and teachers could work better than threats of punishment and invitations to learn from their mistakes.