In your report From Neurons to Neighborhoods, [you] wrote, "It is essential to balance the excitement about all the new learning with caution about the limits of understanding." What did you mean by that?

What we meant by that is that, from a scientific point of view, there's always more to learn, and particularly [in] a new field that's exploding, there's always a tendency to sometimes get a little bit ahead of what we know and think we know more than we do. On the other hand, we do know a lot about the development of the brain. We're learning more all the time. So the caution is really to be careful about what's not quite ready for prime time yet, in terms of application. ...

What does neuroscience tell us about the way young children's brains develop?

Actually, neuroscience per se is telling us very little about how young children's brains develop. Most of what we know is from animal studies. But if we take all of what we've learned from animals and some of what we're just beginning to learn from humans, what it tells us is that all of the experiences that young children have are influencing the development of their brain.

So what does it say about actually cognitive learning, intellectual gain?

What the brain science tells us about cognitive and intellectual gains is very general. It tells us that as you learn more, your brain is changing. That's what it means to learn more. All of that has to do with brain function. But at a very specific level, we don't now very much about brain development as it relates to cognition in young children.

A lot of money was put into programs like Head Start and Early Head Start, all kinds of preschool programs. And one of the goals was to enhance early cognitive development. What do you think about that goal, and also the amount of money that's been spent on these programs?

Maybe it would be better for me to answer what the science tells us rather than what I think.

We have very good evidence that well-designed and well-implemented early childhood programs, like a good quality Head Start program or other kinds of interventions, can definitely shift the odds toward better outcomes for children, in a range of areas -- how they think, how they feel, their social development, their intellectual development, their language. There's no question from the research that we could improve outcomes over the short term and, in some cases, over long term for children.

But the question of how much public funds should go into this is more a question of whether we're getting value for our dollar by putting it into high-quality programs. The problem is sometimes we take a good model that's been shown to work, and then we try to bring it to scale and do it to serve more children for less money, with less well training of the staff; and we get more confusing and equivocal findings. So that's the problem.

The problem is not whether early intervention is a good public investment. The problem is whether we invest in high-quality services that are shown to make a difference. And as we found in our report, although the science tells us interventions can be effective when they're administered early, effective interventions are not simple. They're rarely inexpensive, and they're not always easy to implement. ...

Why do you think proponents of early childhood education use the brain research to help raise money for their programs?

We can have a cynical view of that, and we can have a kind of a more generous view. The cynical view is that brain research captures people's attention and imagination. The public responds to stories about brain development, so that's a cynical view. It's a good strategy to get attention. But the more generous view is that, if we're concerned about the impact of early experience and interventions on children's abilities, on children's competence, on how your intellectual development is going on, on how they're progressing socially, we're talking about the brain. That's where all of these things happen.

The disconnect is that we don't have a lot of brain science related to many of these early interventions. So people are really making guesses; they're making extrapolations. But they're good guesses, because if we see effects of interventions that produce gains in confidence and gains in development, then we know by inference that it's the brain, even though we haven't studied that in the brain per se. We've studied it in looking at development and behavior, which is really another way of looking at the brain.

Many people think that brain research is restricted to looking at the cell structure of the brain, looking at the effects of the chemical systems in the brain. That is a way to study the brain. But another way to study brain development is to look at what people are capable of doing, because it's the brain that really determines that.

Do you think there is a "myth of the first three years?"

It depends on what you mean by a myth. So if you ask me is it a myth that what happens in the first three years determines everything that happens afterward and the window shuts at age three? Absolutely that's a myth. It's just not true.

If you ask me whether the first three years are a very important time in which rapid brain growth is taking place and brain development is proceeding in a very rapid clip and that experiences really affect that development, and affect it in a very big and important way in the first three years? That's not a myth. That's the truth. That's science. It's absolutely true.

New research shows that there is an explosion of growth in the brain around the 11-year, 12-year mark, and then a subsequent pruning back of that growth. What do you think of that research, and what does it say?

Well, I'm less of an expert on development in the early adolescent years than I am in early childhood. But there's a clear message that goes across the whole life span. Brain development starts before we're born, and brain development continues until we die, or until we're declared brain-dead, which is one way of defining death.

There are predictable periods in which there is more rapid development of the brain, [and] in which there's more gradual development. There are parts of brain development that involve the expansion and proliferation of connections. There are parts of normal development that involve a pruning back. All of this is very biologically programmed, but also heavily influenced by experience and by the environment. It just differs from one age period to another, and we're learning more and more all the time what those differences are.

It's not a different kind of process at one age from what it is at another. It's always an interaction of your kind of genetic makeup and your environmental experiences. It's just that different parts of the brain mature at different ages. Different parts of the brain are more plastic or more open to change at different times than others. But it's the same process that really continues, as best as we know it at this point, all the way through.

If there is an explosion of growth and pruning in those early adolescent years, we also see that there are great vulnerabilities of the teenage years. It seems similar to this period of early childhood. A lot of resources were poured into early childhood. You may not think there was enough, but there was a lot. Do we need the same sort of resources poured into the teenage years?

... If you invest early and create a strong foundation, it's easier to get a better return on your investments later, because you're just building on strength. If you don't invest early and you have a weak foundation, then your later investments are trying to make up for deficiencies. Some of the gains may be just trying to regain ground that you've lost. So I think it's a big mistake for us to ask about whether we should invest early or late.

In fact, when we invest early, if we stop investing -- particularly for children who are facing risks in their lives -- we lose some of the gains, the positive gains of early investment. If we wait and allow children to go without help who are at risk and we save our money to invest later, we're starting from further back; in fact, we're trying to make up ground, and we won't get as good a return on investment. So I think we have to think of this as a lifelong perspective. ...

What created the "myth of the first three years" that John Bruer talks about in his book?

The problem is that parents were getting two very strong messages that seemed to be coming from credible sources, saying the opposite thing. One message was saying that if things don't happen in the first three years, it's going to be difficult -- if not impossible -- to make that up. And another very strong and authoritative message was saying there's nothing special about the first three years that's different from any other.

The lesson that we can take in terms of public education on this issue is that any kind of overly harsh statement in one direction or another is unlikely to be completely true, because the truth really is somewhere in between those two extremes. And this is where the truth is. Are the first three years of life important? Absolutely. There's no question they're important.

Does the window shut at age three on certain things and it's too late to do anything about it? Absolutely not, when it comes to intellectual development, language development, social or emotional development. There are critical periods early in development for children; but they tend to be in very tightly defined areas, mostly around things like vision, kind of an auditory perception. There are relatively sensitive or critical periods there.

But when it comes to things like intellectual development, emotional development, their social development, there is not a shred of evidence that there's a critical period for any of those dimensions. At the same time, the first three years are very important for the foundation in each of those areas. So this is kind of where the truth is. It's both important, but not the be-all and the end-all.

The danger of the misinterpretation is to go to either of two extreme falsehoods. One is that it doesn't matter, therefore it doesn't matter what happens in the first couple of years; you can always make it up later, therefore don't waste public funds and invest. That's a huge mistake. That's against everything we know about science.

Another danger would go to the other extreme and say, "Put all of our investments in the first three years, because that's where it really matters, and let's not worry about investing afterward." That would be a huge mistake. Both of those would be mistakes, not just because it doesn't make sense, but because the science doesn't support that at all. It's nice when science and common sense come together. I think this is one example where they both come together.

But there is only a finite pot of money. People have to make decisions to spend it in one way or another.

Right.

So where do they get guidance on that?

To the extent that science can provide guidance, the answer from science would be to take a long-term perspective -- think about what the different needs are at different points in the life span, and to be really smart about how you make your investments.

And the other issue here is that we need to bring in more into the policy debates. The argument should not just be whether we should spend more or less money at a given age period. The argument should be, "What's the smartest way to invest our money? What's the best way to get the biggest bang for the buck?" What that means is there are some ways we're spending money early on where we're not spending enough. There are other areas where maybe we're spending more than we need to spend.

So it's being smart about it, and making strategic investments and thinking long term. If you're interested in the early years, also think about the years that follow, because if you get positive gains from early investments and then you pay no attention, what happens afterward [is that] children in high-risk environments will lose the gains that they've made early on. ...

Do you sense that there is a political agenda out there right now about these issues of learning?

I think there's always a political agenda out there around learning, and the politics change over time. And I don't think it's realistic for us to expect that that issues around children's needs and families' needs would ever be apolitical. What's important is that we separate out the political agenda, which is real, from what the knowledge base is.

And I won't pretend to think that knowledge will totally drive our politics. But certainly if we're interested in achieving certain goals, if we're interested, for example, in enhancing school readiness and recognizing that it's a political issue, at least answering the question of how we enhance school readiness, would depend a lot on what we know about what children need to be ready for school. And that is first a knowledge-based question. Then we can take that knowledge and decide how it's going to play out on the political arena.

But what gets us into trouble sometime is that the politics defines the knowledge. And then we have very strong positions on programs that really are disconnected from the knowledge base, and that's unfortunate. It's really imperative that we can separate out what do we know from what do we believe and what are our political values. And then we can make a decision as a society about where to go. ...