Editor’s Notes: In this TEDx talk, psychologist Martha Deiros Collado discusses the impact of smartphones on child and adolescent brain development, emphasizing the need for metaphorical “seat belts” to ensure digital safety. She explains how the teenage brain is uniquely sensitive to social pressure and habit-forming algorithms, which can bypass traditional parental safeguards. To navigate these challenges, Dr. Collado advocates for the “family phone pledge”—a collaborative agreement to establish healthy boundaries and prioritize real-world presence over digital distraction. (April 7, 2026)
TRANSCRIPT:
The Seat Belt Analogy
MARTHA DEIROS COLLADO: Who remembers being in a car without a seat belt on? Maybe you felt adventurous, freeing, I don’t know. But imagine I now say to you, okay, but now you have to take those kids all the way down to London without a seat belt. How do you feel now? Do you feel unsafe, worried, maybe a little bit scared?
And what about now? How does this photo make you feel? Now, I do not want you to be scared about smartphones. I’m actually very anti fear mongering. But just like cars are not good or bad, I believe that we need to find some safeguards.
We created a seat belt to make cars safe, and we need to do the same with smartphones. And I’ve got some ideas, but before we talk about that, I want to talk about child and adolescent development.
Understanding the Adolescent Brain
So one of the things that we think about in adolescence is that they go through these hormonal spikes and big physical transformations, but the most critical change happens somewhere we don’t see — in their brain. And it is in adolescence where all the kind of good juices of development happen. And one of the things you need to know about the brain is that it develops backwards.
So the back happens first and the front last. And in the front, just behind your forehead is the prefrontal cortex. And this part of the brain is really important. It’s the thing that buffers your big emotions. It’s the thing that helps you make good decisions. It’s the thing that moderates your impulses and allows you to initiate tasks. But it doesn’t fully develop until our twenties.
And I know lots of adults feel like they’re still maturing, but it’s really essential knowledge that actually it’s not till our mid twenties that our brain fully matures and the structures stay the way that they are. And in some ways, this is super smart because adolescents and children have this incredible opportunity. They are able to have loads of experiences, make tons of mistakes, and keep learning before the brain kind of stocks it all up.
Synaptic Pruning and Why Exposure Matters
But there’s a catch. One of the things our brains are supposed to do is make predictions. That’s actually their main job. So it’s trying to make the best guess about what happens next. But it’s also in adolescence where this thing called synaptic pruning happens, and I think of it as decluttering the brain.
So the experiences teenagers are having either become really strongly connected in the neurons or they kind of waste away. And so exposure really matters. There’s some studies around smoking and it’s really interesting to know that actually if you’re a 13 year old and that’s when you light your first cigarette, you’re more likely to become a long term smoker in adulthood — 43 percent more likely. But if you light your first cigarette at 21, that likelihood drops to 10 percent. So in these critical brain formative years, what our young people are experiencing actually leads them forward into the future.
And it’s not just cigarettes. It’s everything. It’s the experiences that they’re having.
How Smartphones Bypass Parental Safeguards
One of the things smartphones do is they bypass the kind of normal parental safeguards. So with cigarettes, you’re hopefully educating your child about cigarettes and the health risks. You’re maybe leading by example. But when it comes to smartphones, one of the tricks that they play is that even if you use really strong parental controls, we’ve got evidence that the algorithms will feed 13 year olds on their first login harmful content — be it pornography, misogynistic content, violence — and that’s you using your best parental controls.
But it’s not just the content, because I think that’s the thing that gets talked about all the time. There’s something else that smartphones do to our kids.
Kerry’s Story: A Window Into Teen Anxiety
I see teenagers day in day out in my therapy room, but I’ll never forget this 13 year old who I’m going to call Kerry, but it’s not her real name. One of the things that she came to me for was overcoming anxiety, and anxiety was playing the usual tricks that it plays on everybody. She was scared to go to school and interact with her friends. It was getting in the way of her sleep, and it was really messing up with her studies.
Now, her parents had very firm boundaries around her smartphone. She had one but she had no social media and she was not allowed it after 7 o’clock at night. But Kerry, every morning when she woke up, had 200 messages waiting for her in her WhatsApp. And in the morning, she started fantasizing about what she’d already missed out on. The first thing she did was grab it and then she would dive straight into her screen and wouldn’t look up until she’d read all the messages.
Now I think it’s easy to think, “Oh, Kerry’s a special case.” But actually, I really don’t think that she is. And if you’ve ever met a teenager, you will know that they talk a lot. Now maybe not to you, their parents, the adults, but they talk to their friends. They talk to their friends about everything and anything because part of adolescence is about connecting and finding a sense of belonging with each other, and this is really healthy.
The problem with smartphones is that that quantity of messages would make anybody feel social pressure.
But to a teenage brain that is developing, that is sensitive to experiences, that is also building habits every single time it beeps or rings at them, this is overwhelm.
Habits, Identity, and the Smartphone Trap
And habits are not just things that you do over and over again. Habits are things that we build in relationships with each other. Good habits or bad habits, when we hold them and repeat them, they’re often things that are emotive to us and they have meaning. They have some kind of built in identity for us and that’s why we carry on doing them.
And what I want you to know is that this is really important when we’re thinking about smartphones because our smartphones are training us to have some terrible habits. You and I, we’ve all got them. As long as you’ve got a smartphone, I promise it’s happened. And they trick you.
So a couple of things. It starts with modeling. It’s that minute when your child is talking about their latest Pokémon swap or maybe the last thing that they saw on their favorite series and suddenly, ping, a text comes along, you’re in, you start messaging somebody else. Very quietly, the message you’re actually sending your child is, “What’s on my phone is more important than you.” And by the way, we’ve all done it, me included.
It’s using it as an emotional crutch. So your child is kicking off and there’s people around. So you quickly get your phone out. “Let’s give them something to watch. Shh. Keep them quiet.”
It feels like environmental cues that are just inbuilt in our smartphones. They ping. They buzz. They have colors. And who’s ever felt their phone vibrate in their pocket and you look at it and — nope, that was a phantom buzz. Didn’t exist. Our phones have trained us. They’re really clever.
And when it comes to identity, how easy is it to see those notifications on your WhatsApp from your friends group and say, “I’m just going to let that go. I’m not going to check it yet.” To a young person, that feels like a personal injury because having to wait to read that message is really hard.
And I know that one of the things parents say to me is, “If I don’t get my kid a smartphone, they’re going to be left out.” But I want you to know that they will be more left out and it will amplify this — bigger the day you get them a smartphone.
What the Research Tells Us
Now studies on smartphones are iffy. They’re not very good. They’re quite flawed. But there is this big global study with 100,000 children in it, aged 5 to 13. And this isn’t to scare you, but I think awareness is important.
One of the things that they found was that the earlier your child owns a smartphone, the more detrimental the impacts long term. So ideas around suicide ideation double compared to if they start owning one at the age of 13. The same is true for facing challenges and learning how to cope. And of course, 5, 6, 8 year olds, they haven’t got the developmental skills to cope with life yet. That’s what living is all about. Things like poor sleep, more aggression and irritability, and the one that always gets to me — that they feel like they’re not good enough.
And what I want to bring here is a little bit of nuance because children who come from dysfunctional families, who have poor peer networks or sense of belonging, who maybe have mental or physical health conditions — they’re the kids who are going to spend more time on their phones because their phones are distracting them from a life that is really difficult. And the way I think about it is, in some ways, that’s a coping strategy.
But for the kids who are just sensitive, normal teenagers who are developing, who are more sensitive to experiences because of where their brain is at, a smartphone can still amplify these things. And the earlier we give it to them, the less time they have to build real life skills. Because remember, our brains are making predictions. And if kids are making most of their predictions online, they’re missing this opportunity to build them in the real world.
The Family Phone Pledge
So what can you do? Well, I know lots of parents of my generation are delaying smartphones for as long as they can and I think that’s so helpful. But delay is a process, it is not an outcome. And before we give kids a smartphone, or give little hands that equipment to hold, we should be giving them metaphorical seat belts.
The family phone pledge is something that is not a contract. It is not going to get you punished if you get it wrong. It’s not something that has terrible consequences. It’s an agreement between you and your children that what you value most in your home is each other. And you can make changes and build these healthy habits that I just mentioned every single day in the experiences that you have with your child.
So for example, my 6 year old said, “I don’t want smartphones in my playroom,” because what she wants is me, my full presence. I said, “I don’t want smartphones at the table because I like chatting while I’m eating and I will miss the fun of that if there’s a smartphone beeping.” And we all agreed bedtime is a place where smartphones should not exist because we all want to rest.
And the reason why it works is because we made this agreement together. So my daughter is on board because she’s already got the expectation laid out way before she owns a smartphone.
Building Richer Memories
And I do warn you that if you do this, your house will look like chaos. This is my house. This is a den they built and it is going to get louder, noisier, there’s more arguments, there’s music, there’s laughter, there’s presence, and there’s more memories.
And one of the things I want you to know about memories is that our brains encode richer memories when they’re experienced fully, when you embody them. So for example, if you listen to a band on the radio and you love the song and you know all the lyrics, it is not the same kind of memory in your kitchen than if you watch them in real life and you see them play, you hear them, you feel the bass through your body, and you smell the crowd. That memory is rich.
And every single time your phone pings at you, and you pick it up and you’re in the middle of an interaction with somebody else — your child perhaps, or an experience — that’s a glitch in your brain’s memory system.
Why Banning Isn’t the Answer
So why don’t we just ban them? Because it’s so much easier, and as a mom, I feel like I’d love that backup of “let’s ban smartphones and my life is easier. I can say no because somebody else said so.”
The problem I have with bans is that, one, anything you ban becomes a lot more seductive to teenagers. They’re going to do it, but they’re going to do it behind our backs, and then we can’t protect them. For me, it’s a little bit like knowing that when they see a red light, they stop. They haven’t got kids to drive a car yet, but over time, you’re teaching them what the rules of the road are. We can do the same thing with our smartphones.
I do think we need to push for apps and big tech to become safer because online experiences should be safe for all of us from the start. But again, as a mom, I have not got the time to wait for governments to wake up, to hope that technology might become more human, or for research to catch up. I have to take action right now.
Taking Action Today
And the action I’m taking is I have an open dialogue about smartphones in my house. I am setting the expectation straight away, and my daughters are 6 and 2, and I’m following the family phone pledge to guide me, to help me, and delaying smartphones for as long as I can in my house — 15 — because I know that one day, when my daughters walk out the door, it will not be the lectures I gave them that they will remember.
Just like they automatically put on a seat belt when they sit in a car, the things that they’ll remember are the habits, the little rituals that I’m embedding in my home with them. Those are the experiences they take. And when we know better, we get to do better.
And I really believe that we can build a generation — choose to build a generation — of kids who don’t just survive the digital age, but they thrive within it. And when we do this work, as effortful as it is, there is one thing that you are going to take with you — to experience your children’s childhood fully and hold on to those memories for life.
Thank you.
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