Come on a little mind walk with me.
The idea of neuroplasticity — that the brain continues to rewire itself in response to new experience — is widely understood these days. Brain imaging research has shown us clearly that people grow new brain stuff all the time. In my field, this is also called experience-dependent brain development, because the changes come after the experience, as a response to it. So for example, whether you can climb a tree or drive a truck will depend on whether you live in a society that has them; whether you speak English, or Korean, or Arabic will depend on where you grow up and what language(s) your parents speak.
Most, but not all, of our brain development takes this form — we interact with the world, and the patterns of input and repetition shape our brains.
This rewiring capacity of the brain has sparked a very abrupt turn in the national conversation about digital media and kids/teens. Over the past twelve months there’s a growing clamor of voices concerned about addictive patterns of tech use. One question being asked is how tech might be wiring kids’ brains differently — and whether that’s for good or ill.
What’s sparked this conversation isn’t the concern of educators or parents. It’s the confession on the part of tech designers (like Tony Fadell, Justin Rosenstein, and the folks launching the Center for Humane Technology) that tech companies have been engaged in an intentional effort to keep us hooked. That’s not a statement of evil, it’s merely the natural outcome of a profit-motive advertising-based industry. If you’re going to make money, you need eyeballs on your product; if you’re going to get eyeballs, you need to make your product really enticing. This is well understood — the field is even called ‘persuasive design’ — and designers pay good money to learn how to do this better. Some designers, like Nir Eyal author of Hooked: How to Build Habit-Forming Products, have begun speaking about the possible moral and ethical risks.
Notifications play a crucial role in getting our attention and hooking us into our device. A Guardian article from October 2017 identifies Chris Marcellino as one of the two inventors behind Apple’s 2009 crucial patent for “managing notification connections and displaying icon badges.” Marcellino left the tech industry, and is studying to become, as it turns out, a neurosurgeon. Talking about the neural pathways that notifications recruit, he noted:
“These are the same circuits that make people seek out food, comfort, heat, sex”.
Persuasive design takes advantage of the reward-based circuits of the brain — things like gambling and drug use, that light up our dopamine pathways, and keep us coming back for more.
I agree with this new wave of concerned tech designers, many who are new parents: today’s interaction design makes the devices if not outright addictive, then definitely ‘sticky.’ I also agree with those who are starting to speak up on behalf of kids — that this feature is especially a big concern for children in light of what we know about neuroplasticity.
That’s not what worries me though. What I’m worried about is the other form of brain development.
Neuroplasticity is not the only way brain development happens.
The other form of brain development is called experience-expectant brain development. It consists of periods of intensive growth and consolidation in the brain. The first is during infancy. The second is adolescence.
The key difference is that experience-expectant development is going to happen, irregardless of the environmental input. It’s not a response to the person’s experience, although it will be shaped by it. Rather, the brain is getting ready — it generates new dendrites, new myelin, new glial cells — everything that is needed to prepare for the development that is just about to come. And then it clears away what isn’t needed.
Two processes define experience-expectant development: synaptogenesis (the making of new synapses) and synaptic pruning (the loss of existing synapses).
synapses represent the possible pathways thought could take in the brain
1. Building connections— synaptogenesis
Neurons themselves do not touch. The communication is processed across a gap, or synapse. Any neural pathway, like the ones Chris Marcellino talked about notifications tapping into, is a series chemical and electrical signals passing along many thousands of neurons — a sort of ‘pass the potato’ game happening at the speed of microseconds.
In experience-expectant development, the brain is making a lot of new dendrites — which results in a lot of new synapses. This initial oversupply prepares the brain to make massive new connections rapidly — a clear human evolutionary advantage. The oversupply makes possible billions more connections. Just what kinds, though?
More possible connections = More possible learning.
This deepening of the brain’s capacity happens just in advance of certain key times in development: Infancy, and adolescence. The brain is preparing for rapid growth and consolidation.
Well-known milestones in development occur in all typically-developing individuals.
Synaptogenesis supports all this new capacity. The overabundance of new synapses in infancy is what enables babies to learn so much so rapidly. While less is known about synaptogenesis in adolescence, there is some recent evidence to suggest that it does take place. Measures of peak cortical thickness, for example, show that some areas of the brain continue to increase through adolescence.
2. Clearing connections away — synaptic pruning
Whatever isn’t needed is pruned away. That’s the second part of experience-expectant development. Keep in mind, this is a universal process for all humans — pruning is going to happen regardless of what the child does. What gets pruned, though, is highly context-specific.
use it or lose it
It is well understood that infancy and adolescence are periods of considerable synaptic pruning. And this clearing away of unneeded synapses during these periods is what enables the brain to consolidate what has been learned, and to accomplish it more efficiently.
In this pruning process, the neurons themselves are left standing. What is lost is the density of the dendrites, and the potential synapses they afforded. Dendrites involved in active pathways — the ones that are used — will be retained. The ones that aren’t will be reabsorbed by the body. The potential for connection they offered — thoughts, skills, habits — will be gone.
Let’s go back to digital media for a moment.
Think about what is happening in the brains of babies and teens.
Infant brains are proliferating new synapses at a dizzying rate. I suspect teen brains are too, and that we will learn more in years to come. Those synapses offer an incredible resource for new learning, because they make new neural pathways possible. New skills and experiences are laid down into these pathways at an incredibly rapid rate.
A classic example is infants’ vocabulary burst around 16–20 months — they can learn a new word a day, every day, often with only one instance to teach them what this new word means. Teens are capable of incredible mental dexterity, also learning new skills quickly. Just look at any of the big teen challenge competitions — like Google’s Science Fair, FIRST robotics, or Intel’s Science and Engineering Fair — to see the adolescent capacity for deep, methodical, innovative thinking.
While it’s true that the brain develops throughout a child’s life, including some synaptic pruning across the entire period of childhood, we know that pruning is intensified in these two periods of infancy and adolescence.
Because of experience-expectant brain development, infant brains and teen brains are biologically primed to learn new stuff rapidly, and to consolidate it efficiently into the architecture of the brain. In uniquely formative ways, compared to other periods of childhood.
What a powerful time to be using new digital technologies.
No, we don’t yet have the data to show, causally, that tech is damaging kids’ brains. But we do have enough data on other kinds of influences — drugs, alcohol, other teratogens — to know that children’s brains are uniquely vulnerable at specific times.
The parts of the brain coming on line during adolescence — that is, the parts that are experiencing the most synaptic pruning — are the executive functioning centers of the brain in the prefrontal cortex and the connections between those control centers and other parts of the brain.
We know that drug and alcohol use during this particular period of brain development is uniquely damaging. We know, for example, that roughly ages 15–18 are the worst time for kids to experiment with drugs, and that experimentation at later ages, while probably detrimental, won’t stand to do nearly as much life-long damage. Maybe digital technologies work the same way.
Comparing digital tech to a teratogen is an inflammatory suggestion, I realize. But we don’t know that it doesn’t work like one.
Any environmental influence that disrupts development needs to be taken seriously. Morally, socially, and economically we have a vested interest in understanding how digital technology is impacting kids and teens. Not to turn it off, but to understand so we can constrain it where appropriate.
We’re engaged in the largest social experiment of human history as we put powerful, poorly understood technology into the hands of our children. In the space of ten short years we have gone from the invention of the smartphone to near-saturation of internet-enabled mobile devices.
New technology is constantly being introduced, so it is very hard to get up-to-the-minute data. But it is obvious that the landscape of access to digital technology is changing very rapidly. It appears that by now, most kids in the US have their own device, or at least have access to their family’s devices.
We know that persuasive design is good at what it does. We know that the apps on today’s devices are better designed at keeping us engaged and drawn in, even beyond our desires to do so. We’re starting to see there’s a problem.
2017 marked a turning point — the start of a clarion cry to pay attention to this. Addiction specialist Nicholas Kardaras’s August 2016 book Glow Kids lays out a catastrophic picture of the addictive effect tech is having on kids’ brains — it is so strongly worded and hyperbolic in its warnings, I find even myself pushing back on some of his claims. In Spring 2017 the nonprofit Children and Screens’ working group on Families, Parenting, and Media published a review of recent research on Parenting and Digital Media, in Pediatrics, the journal of the American Academy of Pediatricians. In Fall 2017 the child advocacy group Center for a Commercial Free Childhood launched an Action Network for reducing kids’ screen time, and the National Academies of Science working group on Media Multitasking published a review on the Cognitive, Psychological, Neural, and Learning impacts of media multitasking, also in Pediatrics. Now Common Sense Media has partnered with new nonprofit Center for Humane Technology to launch the Truth About Tech campaign.
Digital technologies open up limitless capacity for creativity and problem solving. They also come with unplanned-for implications.
There is so much we don’t know yet. And there are good reasons to be worried, with experience-expectant brain development near the top of the list, given how fundamental it may be to the lifelong architecture of the brain.
How is tech affecting kids? How is it shaping their brains and their futures? We urgently need to be pursuing these questions:
The time to sound the alarms is now. Maybe yesterday.
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