Here’s the New York Times’ #3 article on its online frontpage:
The research could have policy implications as President Biden pushes to revive his proposal to expand the child tax credit.
The differences in brain activity were modest, and it remains to be seen if changes in brain patterns will translate to higher skills.
By Jason DeParle
Jan. 24, 2022
WASHINGTON — A study that provided poor mothers with cash stipends for the first year of their children’s lives appears to have changed the babies’ brain activity in ways associated with stronger cognitive development, a finding with potential implications for safety net policy.
The differences were modest — researchers likened them in statistical magnitude to moving to the 75th position in a line of 100 from the 81st
I.e., from the 19th to 25th percentile.
— and it remains to be seen if changes in brain patterns will translate to higher skills, as other research offers reason to expect.
Still, evidence that a single year of subsidies could alter something as profound as brain functioning highlights the role that money may play in child development and comes as President Biden is pushing for a much larger program of subsidies for families with children.
“This is a big scientific finding,” said Martha J. Farah, a neuroscientist at the University of Pennsylvania, who conducted a review of the study for the Proceedings of the National Academies of Sciences, where it was published on Monday. “It’s proof that just giving the families more money, even a modest amount of more money, leads to better brain development.”
Another researcher, Charles A. Nelson III of Harvard, reacted more cautiously, noting the full effect of the payments — \$333 a month — would not be clear until the children took cognitive tests. While the brain patterns documented in the study are often associated with higher cognitive skills, he said, that is not always the case.
… Evidence abounds that poor children on average start school with weaker cognitive skills, and neuroscientists have shown that the differences extend to brain structure and function. But it has not been clear if those differences come directly from the shortage of money or from related factors like parental education or neighborhood influences.
It could be something that happens in the 8 months and 29 days before birth. But not a day sooner!
The study released on Monday offers evidence that poverty itself holds children back from their earliest moments.
“This is the first study to show that money, in and of itself, has a causal impact on brain development,” said Dr. Kimberly G. Noble, a physician and neuroscientist at Teachers College, Columbia University, who helped lead the study.
Dr. Noble and colleagues from six universities recruited a thousand mother-infant pairs within days of the babies’ birth and randomly divided the families into two groups. One group received a nominal \$20 a month and another received \$333.
Using electroencephalograms, or EEG tests, to evaluate the children at age 1, the researchers found that those in the high-cash group had more of the fast brain activity other research has linked to cognitive development than those in the low-cash group. The differences were statistically significant by most, but not all, measures and were greatest in parts of the brain most associated with cognitive advancement.
I’ll post below the researchers’ rather tortured efforts to reach statistical significance:
… While the size of the recorded differences are modest (about a fifth of a standard deviation), the researchers said they were comparable to those produced by the average school experiment, like giving children tutors. While those services are often hard to administer, they added, cash can be distributed on a mass scale.
A general pattern found in studies over the last 60 years is that it’s not too hard to juice results for very young children, but hard to have much long-term impact after puberty.
From the actual study:
In the case of absolute power, the high-cash gift group showed higher power in the three mid- to high-frequency bands (alpha, beta, and gamma) but not in the low-frequency theta-band (top rows of Table 2). When ranked by effect sizes, group differences in EEG power in the beta-band were largest (effect size = 0.26, beta = 0.414, P = 0.02, for the model with covariates and site fixed effects), followed by the gamma-band (effect size = 0.23, beta = 0.221, P = 0.04). Both P levels were below the 0.05 threshold when treated as independent measures, but not after Westfall–Young (44) multiple-testing adjustments. Group power differences in the alpha-band (effect size = 0.17, beta = 0.720, P = 0.07) were smaller and at the margins of statistical significance. Small and statistically nonsignificant differences in absolute power were found in the theta-band (effect size = 0.02, beta = 0.396, P = 0.83). (See SI Appendix, SI5 for a similar pattern in weighted analyses that adjust for demographic differences between the n = 435 EEG sample and the n = 931 full sample of BFY mother/infant dyads interviewed at age 1.)
Differences in relative power were qualitatively similar but uniformly smaller than those observed for absolute power, with the high-cash gift group showing greater mid- to high-frequency relative power in the alpha-, beta-, and gamma-bands. These differences did not reach conventional levels of statistical significance (bottom rows of Table 2; for a more complete discussion of absolute and relative power, see SI Appendix, SI3). In contrast, relative theta-power was greater in the low-cash gift group with an effect size of 0.21, with the difference at the margins of statistical significance (SI Appendix, SI4). …
Given our hypotheses of positive differences across all mid- to high-frequency portions of the power spectrum, we aggregated power across all three of our preregistered mid- to high-frequency power bands. Such a summary index approach is a commonly used data-reduction technique in the social sciences (45, 46), and serves as a post hoc complement to our preregistered Westfall–Young multiple comparison adjustment.
In other words, they didn’t think of this statistical ploy when they pre-registered their study. (I’m actually sympathetic to researchers who come up with new ideas when they finally get their hands on the real results, but pre-registration purists are not.)
While this approach ignores the biological and functional significance of the EEG bands, it has the benefit of enabling us to statistically estimate ITT differences for a single aggregated mid- to high-frequency index score (SI Appendix, SI7). Consistent with our band-based results, we find that the infants in the high-cash gift group had more mid- to high-frequency band absolute power than infants in the low-cash gift group (effect size = 0.25, beta = 13.35, P = 0.02) (SI Appendix, Table SI7.1). Thus, the direction and approximate size of intervention effects on mid- to high-frequency absolute power are similar when power is analyzed in preregistered bands, disaggregated into single-hertz bins, examined within regions or aggregated across bands.
I look forward to the press conference at which Joe and Kamala try to explain this study.