The Science behind "What were you thinking?!"

Deidre Heafield
Oct 15
2 min read

Understanding Adolescent Risky Behaviours and the Role of the Prefrontal Cortex

If you’ve ever caught your teen doing something so incredibly irresponsible that the spike in your blood pressure nearly put you in the ER , you’ve probably uttered the worn out phrase: “What were you thinking?” Spoiler alert—sometimes, they literally weren’t. Their brains are still under construction, and the part responsible for sound judgment and self-control (the prefrontal cortex) is running a little behind schedule.

The Teen Brain: Under Construction

During adolescence a significant amount of brain development is taking place. The prefrontal cortex — the part in charge of planning, impulse control, and weighing consequences — is the last area to finish developing. Meanwhile, the emotional “reward center” of the brain (prefrontal cortex) is firing on all cylinders, cheering on anything that feels thrilling or new. It’s a recipe for spontaneous adventures, questionable TikToks, and a lot of sleepless nights for parents.

It’s why a teen who knows that skipping school or speeding is a bad idea might still do it anyway. Their brain’s thrill-seeking department is open for business, while the risk-assessment office is still hiring

The Power of Peers

Add friends to the mix, and the stakes get higher. Teenagers are wired to crave social acceptance, sometimes more than safety. The need to belong can nudge even the most sensible teen into joining the crowd — whether that means trying alcohol, vaping, or saying yes to a questionable dare. As parents, it helps to remember that this isn’t rebellion so much as biology. Social approval lights up the teenage brain like fireworks, making peer influence incredibly persuasive.

Emotional Overdrive

Adolescence also comes with emotional turbulence. With hormones surging and stress levels rising, teens often act first and reflect later. Helping them manage big feelings — through sport, creativity, or simply open conversation — can go a long way in promoting calmer, wiser choices.

Guiding, Not Controlling

The goal isn’t to bubble-wrap your teen but to guide them through this exciting, chaotic chapter. Keep communication open, listen without judgment, and talk through consequences rather than just laying down the law. Teens are far more likely to think things through when they feel heard and respected.

The Takeaway

So next time you find yourself sighing, “What were you thinking?” remember — they’re thinking with a brain that’s still learning to balance emotion and reason. With patience, empathy, and steady guidance, you can help your teen turn those impulsive moments into learning opportunities — and maybe even share a laugh along the way.