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Some of the Science Behind the “Threenager” Brain

In America, there’s a phrase called “the terrible two’s.” This phrase refers to the horrendous onslaught of tears and chaos that accompany the average two-year-old psyche.

However, as a parent of two little girls, I can assure you that the “threenager” phase is EXPONENTIALLY more tear-filled and chaotic than any age shy of the teenage years.

Much like their older, pubescent counterparts, threenagers have a difficult time managing their overwhelming emotions because of changes that are happening in their bodies. They may not be developing pimples or mustaches, but they’re developing new capabilities, which change their perspective about the world.

Physically, their brains are going through changes, as well.

As an infant, your child was used to functioning primarily out of the part of their brain that controlled automatic responses, like reflexes, breathing, hunger, and sleep. Once your child moved into toddlerhood, they began to tap into the part of their brain that controls emotion. They started to feel bigger, more complicated emotions than just hunger and sleepiness.

As a three-year-old, those emotions are accompanied by a broader vocabulary and the ability to communicate their feelings (though not always effectively). The problem, however, is that a three-year-old brain hasn’t yet developed the ability to control executive functions. These are processes like organizing, rationalizing, and problem-solving.

So they’ve developed the ability to be VERY sad or mad or lonely or hurt or greedy, but they haven’t yet developed the ability to rationalize why they might be feeling those emotions or to problem-solve what they could do about those emotions.

They’re able to tap into the executive control panel of their brain, but only small bits and pieces of it. They won’t have that eye-opening experience for the first time until they’re in kindergarten or first grade. Then they’ll have to wait another five (or so) years until they get another big increase in abilities.

The big difference between teenagers and “threenagers,” however, is that teenagers are often aware of their own instability, they just don’t know what to do about it.

Threenagers are completely oblivious to their irrationalism, obviously due to lack of wisdom, maturity, and executive functioning control.

So the next time your three-year-old goes through a complete meltdown in the middle of a grocery store because he didn’t get to put the groceries up on the belt “all by himself,” remember that it isn’t really his fault. He can’t control those big waves of emotions, and he really doesn’t understand why you won’t let him do it alone.

Or the next time your little girl gets mad and throws herself on her bedroom floor (literally) because you won’t let her sleep with a handful of dead rollie pollies (actual scenario from our bedtime routine last night), don’t get upset with her. She feels big getting to take care of the little creatures and is completely oblivious to the fact that they’re dead and probably covered in diseases now.

Her brain is telling her that these things are important.

And above all else, DON’T LAUGH AT THEIR EMOTIONAL ROLLER COASTERS! At least not where they can see you.

Giggle with your friends about it and tell them when they’re older, but right now, it’s so important that you validate their thoughts, ideas, and feelings. That’s how their executive control develops further… by you encouraging them and helping them to learn new perspectives!

What’s the funniest moment you’ve gone through during the “threenager” years? This is the perfect place to share it.

But please leave out names and specifics. 🙂

Some of the Science Behind the “Threenager” Brain



APA Reference
Cummings, W. (2018). Some of the Science Behind the “Threenager” Brain. Psych Central. Retrieved on January 16, 2019, from


Last updated: 29 May 2018
Last reviewed: By John M. Grohol, Psy.D. on 29 May 2018
Published on All rights reserved.