Spotlight Exclusives

Brain Activity in Babies Boosted by Cash Aid, Study Finds

Dr. Kimberly Noble and Greg J. Duncan Dr. Kimberly Noble and Greg J. Duncan, posted on

The potential impact of unrestricted cash aid for Americans with low incomes has long been a topic of debate in policy circles, and the COVID-19 pandemic forced an unexpected experiment through programs such as the expanded Child Tax Credit. Adding to a new urgency around the cash aid debate is the first set of results from the Baby’s First Years project, the first study in the United States to assess the impact of poverty reduction on family life and infant and toddler’s cognitive, emotional, and brain development. Two of the study’s leaders, Dr. Kimberly Noble, a physician and neuroscientist at Teachers College, Columbia University, and Greg J. Duncan, an economist at the University of California, Irvine, spoke to Spotlight about the results and their importance. The conversation has been lightly edited for length and clarity.

Why don’t we start with the basics of what the study is trying to do and what this first set of results represents?

Kim Noble:  Sure. We’ve known for a very long time from work by Greg and others that kids and families in financially disadvantaged, financially oppressed situations and communities tend to be at risk for a host of outcomes—everything from lower school achievement to lower likelihood of employment and reduced earnings in adulthood to poor health in adulthood as well. But of course, many people would say poverty is not causing all of those problems. Instead, poverty is merely associated with those differences, and it’s really adults’ choices that are causing those differences and outcomes for their children. So, regardless of where you sit on that question ideologically, from a scientific perspective, the best way to really answer it is through a randomized controlled trial.

Now of course, you can’t randomize families to living in poverty or not, but you can take a group of families who are living with low incomes and invite them to participate in a randomized trial in which they receive different amounts of monthly cash support. And that’s the basis for the Baby’s First Years randomized control trial. In the spring of 2018, we began recruiting a thousand mothers living with low income, shortly after they gave birth, in four metro areas around the United States (New York City, Minneapolis-St. Paul, New Orleans and Omaha, Neb.). Mothers were recruited within a day or two of giving birth right there in the hospital postpartum wards, and upon enrolling in the study, mothers were offered the opportunity to be randomized to one of two monthly cash gift amounts. The group that we call the High-Cash Gift Group is receiving $333 a month or $4,000 a year. The group that we call the Low-Cash Gift Group is receiving $20 a month or $240 a year. And we chose those amounts very intentionally.

Now, back when we started planning the study 10 years ago, we of course didn’t know that Build Back Better was on the horizon and the expanded Child Tax Credit would be debated, but we did reason that $4,000 was an amount similar to other social services and benefits that mothers living with low income may qualify for. So, on the one hand, it seemed to be a policy relevant amount, and on the other hand, work by Greg and others suggested that difference in annual income, about $4,000 a year, was associated with outcomes like higher school achievement or better health down the road. In short, it was an amount that we thought would be both likely to move the needle and that held some policy relevance.

So, we enrolled the families over the course of one year and have been following up with them annually around the time of their children’s birthdays. This first study represents the first findings emerging from that first wave of follow up conducted around the child’s one-year birthday mark. When we started our home visits in the summer of 2019, we were traveling into the homes of the families to conduct a survey and also collect data on infant brain activity. Unfortunately, the pandemic struck in the middle of that age one data collection wave. And so, in March of 2020, we had to pivot from in-person data collection to phone-based data collection. Overall, our retention rates were quite high over the course of that wave, roughly 93% to 94% retention overall, but unfortunately, since we couldn’t collect in-person data after the pandemic struck, we’re limited in this paper to data from the 435 infants from whom we could collect brain activity measures.

In this particular paper, we looked at the impact of the cash gifts on brain activity, but what is brain activity? Why do we care about it? We can measure infant brain activity using a technology known as electroencephalography or EEG. We use a cap that fits on the baby’s head, and the baby usually sits on their mother’s lap while we take the measurement. The cap has little discs on it called electrodes, which you can think of kind of like microphones that listen in to the brain’s electrical signals. Now, of course we’re not mind readers. We don’t know what someone’s thinking. But we are able to measure how quickly the brain is sending electrical signals back and forth. We all have some slow brain activity and some fast-paced brain activity, but we care about the amounts of slow and fast brain activity for several reasons. First, we know that in childhood, as kids get older, they tend to have more fast-paced brain activity. Second, we know from some past correlational work that on average, kids with more fast-paced brain activity early in childhood tend to be more likely to develop higher cognitive skills and other skills that are important for school. And third, again, past correlational work has suggested that kids growing up in poverty or facing other forms of early adversity often have less fast-paced brain activity early in childhood.

And so, we reasoned and hypothesized — and preregistered — that the cash gifts delivered through our poverty reduction intervention would potentially mitigate that pattern. We hypothesized that the infants of the mothers in the High-Cash Gift Group would show more fast-paced brain activity and less slow brain activity than the infants of the mothers in the Low-Cash Gift Group. This paper reports those initial findings, where we see that the infants of the mothers in the High Cash Gift Group are showing more fast-paced brain activity than the infants of the mothers in the Low Cash Gift Group. Now, because of the pandemic, we obtained EEG data from only about half of the sample that we anticipated, and not all of those findings were statistically significant. They were in the direction we anticipated with regard to fast-paced brain activity, but they were not all significant.

So then we did several other tests. I won’t go into all of those statistical details, but the most notable in my view is that that differences in fast-paced brain activity were driven by differences in key brain regions that support the development of thinking and learning. The regions underlying those differences across the whole brain are exactly the regions that have a been correlated with differences in income and differences in impact development. And so, while the evidence is not airtight, as we were very clear to lay out in the paper, we do feel that the weight of the evidence supports the idea that these cash gifts change children’s brain activity.

And does the data indicate at all why, in terms of how the cash was used and specifically what sort of impact the payments may have had?

Not yet. We’re working very hard to try to understand that. We’ve collected a whole lot of data at age one, also at age 2, and now we’re in the field at age three to try to really understand those mechanisms and pathways. We’re collecting data on things like what we call the investment pathway—how families are spending the money, how their time may have been impacted by the cash gifts. And we’re also collecting information on stress and family life and health and nutrition to try to understand other potential pathways as well. So more to come on that.

Greg, as someone who has worked on this topic for a very long time, what do you see the major significance of these results as being?

Greg Duncan: Well, as Kim says, it’s the first clinical trial looking at these things. Over the last 15 years or so, there’s been a fairly strong literature in terms of causal design that takes advantage of things like expansions of the Earned Income Tax Credit in the 1990s, and the rollout of the food stamp program in the 1960s and 1970s. When researchers looked for linkages to achievement, health, and other kinds of outcomes, they usually found them. But getting more Earned Income Tax Credit income required work. In the case of food stamps, the stamps have to be in the first instance spent on food. Those are conditional transfer programs and there really weren’t U.S. studies of unconditional kind of transfers where you’re not requiring the families to spend the money on any particular set of things or requiring them to work in return for the benefit.

So, ours is the first study of unconditional payments and it’s the first study that’s really focused on early childhood—infancy, toddlerhood—which is the time that neuroscientists like Kim tell us the brain is developing incredibly rapidly. It’s a time when children are most sensitive to environmental conditions, including enrichment and disruption. Once children grow older, then their peers and neighborhoods and schools start to influence them. In the early years, their family settings are all important. So, ours is the first clinical trial to provide definitive evidence about the causal role played by poverty reduction on both early childhood functioning as measured by EEG now, and at age four with EEG and other measures. We will also estimate impacts on the stress and investment pathways that Kim is talking about. There’s nothing like a random assignment clinical trial to cut through all of the debate over the kind of confounding factors that Kim mentioned before. Is it really income or is it family structure or something else? This provides much more definitive and transparent evidence because you can directly compare the families in the High-Cash Gift Group and families in the Low-Cash Gift Group. So for both science itself and the communication of results, there’s a big advantage from having this kind of clean clinical trial design.

And were these moms able to accept aid from other government programs?

Noble: We worked very hard before the launch of the study to make sure that, to the extent possible, moms would still be eligible for all of the other programs they otherwise would’ve been. This was work led by two of the other PIs, Katherine Magnuson, Director of the Institute for Research on Poverty at the University of Wisconsin Madison, and Lisa Gennetian, a professor at Duke’s Sanford School of Public Policy. In two of the four sites, our team essentially went agency by agency to take care of these kinds of waivers. And then in the other two, we actually managed to get state legislation passed saying that for these moms in this study, this money will not count toward their eligibility for social services. So, to the extent possible, moms are still able to get whatever they would’ve normally got. We are asking them about the receipt of social services, and most of the moms gave us permission to track administrative efforts so that we can objectively measure that too.

Duncan:  I might add that there’s a broader set of environmental, policy and cost of living differences across the country that we worried about. You could imagine the $4,000 going further in a low-cost state or site like New Orleans, or maybe more in Omaha than in New York city. You could also imagine that the considerably more generous state benefits in New York and Minnesota might affect the impact of our low cash versus high cash comparison more than Omaha and especially Louisiana, which is a very low benefit state. We were agnostic about which of those kinds of factors would be most important. We didn’t want to put all our marbles on one particular site with one particular combination of cost of living and benefits. So, we came up with this idea of trying to have this diverse set of sites that collectively would represent the kind of diversity of policy environments and employment conditions that we see in the United States as a whole.

The release of these initial results has come, as Kim mentioned, in the midst of the Build Back Better debate and the debate about the expanded Child Tax Credit. I know you’ve been very careful to stress what these results show and what they don’t show, but you are being used by some as a bolstering argument extended the expanded CTC. Do you think that’s a fair use of this data?

Duncan: That’s a great question. We try to be very careful in how we write up our results and in the policy discussions that we provide in this paper and in our other papers. Ours is not a child tax credit. Our money is coming from philanthropy. It’s distributed on a debit card with a logo that says, “4MyBaby.” It’s not coming from the government. And it’s just a single payment per family, rather than a payment per child in the family. So, there are quite a few differences between our payments and the expanded Child Tax Credit. So, we certainly don’t take the step of claiming that our results have direct implications for an expanded Child Tax Credit. All researchers know that their findings might be used for any number of purposes in terms of promoting different kind of political agendas. We want to be clear from our end about what we found and what we didn’t find. We certainly want to know whether our findings are being used and maybe abused, but we see our role as being the producers of potentially useful information and we really have no control over the next step that advocates take in using the information for their particular purposes.

Kim, would you like to add to that?

Noble: As the neuroscientist and pediatrician of the team, I can talk about the effects on brain activity, the effects on child development. I try not to wander too far into the policy lane. My social science colleagues tell me that the findings are suggestive of the extent to which economic support can potentially promote parents’ investments in children.

What’s coming up next in terms of results?

Noble:  Quite a lot. We’ve got a number of papers in the pipeline in various stages of preparation and under review. We’ve got some work in the pipeline on expenditures—how are families spending the money, specifically child-focused expenditures, as well as addressing a question that we get all the time about the likelihood of families squandering the money. So, we’re looking at things like substance expenditures and substance use. We have work underway looking at effects on employment and work underway looking at effects on family life. That’s all for the most part talking about age one, and we’re also working on analyzing and digesting our age-two findings and monitoring the age-three data collection that is currently underway in the field.

And what I’m personally most excited about is that we are planning and piloting for a resumption of in-person data collection. At around the children’s fourth birthday, we’re going to be inviting the families into our university research settings to once again be able to measure brain activity so that we have a much larger sample, and also, most importantly, engaging in direct assessments of cognitive behavioral development. It’s our chance to actually be able to see at preschool age, what is the impact on child development of regular monthly unconditional cash support for the first four years of life?

And I should mention also that clearly child development doesn’t stop at age four. Ultimately, we hope to be able to follow these kiddos through adulthood. For now, we are thinking ahead and raising funds towards the next several waves of data collection at ages six and eight.


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