An eight-year-old in a Massachusetts cohort scored, on average, half a standard deviation below the pre-pandemic national average for their age on a standardized executive function assessment. That single number, drawn from a study of more than 3,100 children, is the clearest evidence yet of what teachers, parents, and clinicians have been describing since classrooms reopened: something happened to children’s self-regulation during the pandemic, and the recovery has not arrived on its own.

Three peer-reviewed longitudinal studies published in the first half of 2026 have now converged on the same conclusion. Children whose early years coincided with pandemic disruptions are showing measurably weaker executive function skills than children assessed using the same instruments before 2020. The deficits cut across socioeconomic lines, persist years after schools reopened, and have been documented on two continents using direct, task-based assessments rather than relying on parent or teacher reports.

The convergence matters. Earlier reports of post-pandemic developmental disruption have been criticized for relying on caregiver questionnaires, cross-sectional designs, or comparisons across cohorts using different measures. The three new studies use repeated, direct assessments of the same children before, during, and after the pandemic’s onset. They reach the same conclusion through different methods, different samples, and different national contexts.

What they document is not a small effect.

The Harvard Study: A Half Standard Deviation, Population-Wide

The most prominent of the three studies, published in Child Development in March, was conducted by Stephanie M. Jones, Caitlin M. Dermody, Alan F. Mozaffari, Jen Acosta, and Nonie K. Lesaux of Harvard University and the University of California, Berkeley. The research drew on the Early Learning Study at Harvard, a population-based longitudinal study of 3,107 children in Massachusetts followed from 2018 to 2023.

The sample was demographically substantial. Half of the children were girls. Three-quarters were identified as white, with 18.3 percent Hispanic, 11.8 percent Black, and 10.7 percent Asian. The income distribution skewed middle and upper-middle class, with nearly half of families reporting incomes between $75,000 and $200,000, around twenty percent above $200,000, and roughly thirty percent below $75,000. The breadth matters because it allowed the researchers to test whether pandemic effects varied across socioeconomic lines, and to compare children’s scores against a nationally standardized assessment.

The assessment was the Minnesota Executive Function Scale, a tablet-based, direct measure of children’s executive function that does not depend on parent or teacher report. Children were tested in person during three pre-pandemic waves between February 2018 and March 2020, then virtually during two post-pandemic waves between February 2022 and June 2023. The analytic approach used piecewise polynomial regression and mixed-effects growth models to estimate executive function trajectories before and after the March 2020 statewide shutdown, using age 7.5 years as a cutoff marker.

The findings were unambiguous. Before the pandemic, children in the sample were performing at or above the national average on direct assessments of executive function. After the pandemic’s onset, the average rate at which executive function grew was lower than developmentally typical based on pre-existing national norms. The pattern held across all socioeconomic subgroups.

The magnitude is what makes the finding consequential. The average standardized score for an eight-year-old in the study fell by approximately 7.5 points on a 100-point scale, roughly half a standard deviation below the national pre-pandemic average for that age. In educational research terms, a half-standard-deviation difference is the difference between a child performing at the 50th percentile and a child performing at roughly the 30th percentile.

The correlation between children’s pre-shutdown and post-shutdown growth trajectories was 0.21, suggesting that individual differences in executive function growth before the pandemic were only weakly associated with growth trajectories after. The disruption appeared to scramble what would otherwise be a predictable developmental pattern.

What the Authors Said

“Executive function is an essential cognitive capacity that develops rapidly during early childhood and is shaped by early experiences,” the author team told the Society for Research in Child Development. “Therefore, we were not surprised that an extreme disruption like the pandemic affected the development of children’s executive function skills. That being said, the magnitude of our findings was surprising. Children’s scores in our sample were significantly below the nationally normed average scores of age-matched children measured before the pandemic.”

Caitlin Dermody, a doctoral student at the Harvard Graduate School of Education and co-author of the study, described in interviews how the relevant skills typically develop during the early school years. Children, she noted, are usually making major gains in executive function when they begin school, learning to remember to bring lunch and snacks, put them away during the day, and bring lunch boxes home in the afternoon. Stephanie Jones, the study’s first author and a professor of early childhood development at Harvard, has described the same period as when children practice self-inhibition by learning to raise their hands rather than shout out answers.

Those everyday classroom rhythms, the researchers noted, were precisely what was disrupted.

The Tulsa Study: A Decade-Long Cohort, From Kindergarten Through Fifth Grade

While the Harvard study captured a broad population, a second 2026 study tracked a more demographically narrow cohort over the longest pre/post-pandemic window currently published. The paper, by Anna Wright of Georgetown University and colleagues, was published in Developmental Psychology.

The cohort comprised 667 race-ethnically diverse, elementary-aged children from low-income families originally recruited through the Tulsa School Experiences and Early Development (SEED) Study. The researchers followed the same children from the fall of kindergarten in 2018 through fifth grade in 2023, using random-intercept growth models to estimate development in two key executive function skills as a function of school closures.

The study’s methodological strength lies in the direct, repeated assessments. Most prior research on pandemic effects on children’s cognitive development has relied on caregiver reports, single-point comparisons across different cohorts, or retrospective designs. The Wright team had direct measurements of the same children before, during, and after the pandemic-affected period, allowing them to estimate growth trajectories rather than infer them.

Their findings reinforce and extend the Harvard team’s. Executive function development slowed substantially during school closures. The growth deficit was associated with reduced compliance with remote learning expectations, suggesting that the children who struggled most with remote learning were also the children whose underlying executive function development was most disrupted, though the direction of causation cannot be cleanly disentangled.

The Teacher Perception Finding

One of the more striking findings to emerge from the Wright cohort concerns the gap between subjective and objective measurement. Teacher perceptions of children’s executive function appeared to shift during the pandemic in ways that did not always track with direct task-based assessments. In particular, for children transitioning into kindergarten right after the lockdowns, teacher ratings showed declines while direct assessments showed the expected developmental gains.

The implication is significant for practitioners. If teacher ratings and objective task data point in different directions, the question of which source better reflects what a child can actually do becomes a practical one. The finding suggests that pandemic-related changes in classroom expectations, in teachers’ calibration of what is age-appropriate, or in the conditions under which teachers were observing children, may all be inflating perceptions of executive function decline in ways the direct data does not support.

The same study also found that families who experienced greater COVID-related disruption tended to have children who showed lower executive function on objective measures, reinforcing that family-level stress was a meaningful risk factor for the children’s cognitive development.

The University of East Anglia Study: A British Replication

The third major study was published in Child Development by Eleanor Johns, Samuel H. Forbes, Lourdes M. Delgado Reyes, Charlotte Buck, and John P. Spencer, a research team led from the University of East Anglia in the United Kingdom, in collaboration with Lancaster University and Durham University. The cohort comprised 139 children, 71 of them girls, followed longitudinally from ages 2.5 to 6.5.

The same Minnesota Executive Function Scale used in the Harvard study was administered to the UK cohort, with 94 families completing assessments before the pandemic. Individual differences in executive function ability were stable longitudinally, and as expected, children whose mothers had higher levels of education tended to have higher executive function scores. The familiar gradients of executive function development were intact.

The pandemic disrupted them. Children tested in the first one to three years after the first lockdown showed greater variation in individual differences over time than would have been expected. More strikingly, the study identified a specific cohort effect: children who had already started formal primary school during the first lockdown showed slower gains in executive function compared to younger children who were still in preschool when the pandemic hit.

The finding is counterintuitive only on the surface. Younger children, who in many cases simply continued at home in conditions similar to the ones they had before, were less disrupted than the cohort whose first year of school structure had collapsed.

“Children who were in reception when the country shut down showed much slower growth in key self-regulation and cognitive flexibility skills over the next few years than children who were still in preschool,” said Professor John Spencer of the University of East Anglia School of Psychology, the study’s senior author. “These children found it harder to shift between tasks and control impulses, abilities that usually improve rapidly once children enter structured school environments.”

“Reception is a critical year for peer socialisation,” Spencer added. “It’s when children learn classroom norms and build early friendships that shape their confidence. But for the cohort who started school in 2020, classrooms were closed, routines collapsed overnight, and opportunities for social interaction were severely limited.”

The Income Question

One of the more unexpected findings to emerge from the recent research concerns socioeconomic status. Decades of research have established that children’s executive function development varies by family income, with children from lower-income households typically showing weaker skills at school entry. That pattern reflects the cumulative impact of stressors associated with economic hardship, including reduced access to enriching early environments, higher levels of household stress, and less stable caregiving conditions.

The pandemic, in the Harvard data, appears to have flattened that gradient. According to the research team, the well-documented pattern of variation in executive function by income was present in their sample prior to the pandemic. Once the pandemic began, income-based gaps appeared to narrow. Higher-income children, who would ordinarily have been buffered from many of the developmental risks associated with disruption, were also affected.

The narrowing is not a story of progress. It is a story of an unusually wide-reaching shock. The researchers were explicit that the pattern reflects damage to the previously advantaged group, not improvement among the previously disadvantaged. Lower-income children remain disadvantaged in absolute terms. The gap narrowed because the relative protection that household resources usually confer was overwhelmed by the scale of the disruption.

The finding has implications for how schools and policymakers think about intervention. Targeting executive function support only at populations historically associated with executive function deficits would miss a substantial share of currently affected children. The new research suggests the affected population is broader than the populations that traditional intervention programs are designed to reach.

The Tulsa cohort, drawn entirely from low-income families, complicates this picture in a useful way. The Wright team did not have a higher-income comparison group within their sample, but they did document substantial executive function disruption in children whose families had already been managing the kinds of stressors associated with economic hardship before the pandemic added on. The disruption stacked on top of existing pressures rather than substituting for them.

What Executive Function Is, and Why a Half-Standard-Deviation Gap Matters

Executive function refers to a set of higher-order cognitive processes that allow humans to set goals, plan, hold information in mind, regulate attention, control impulses, and adjust behavior in response to changing circumstances. The field generally divides the construct into three core components: inhibitory control, working memory, and cognitive flexibility. Self-regulation, the behavioral expression of executive function, is the umbrella term most familiar to teachers and parents.

Executive function is sometimes treated as a soft or secondary outcome in education policy debates, overshadowed by reading and math scores. The research literature does not support that framing.

Executive function skills predict math and reading achievement across the school years, often more reliably than IQ does. Strong early executive function predicts career and marriage satisfaction in adulthood, and predicts positive mental and physical health outcomes decades later. The classic longitudinal work by Terrie Moffitt and colleagues, conducted in New Zealand and tracking more than a thousand children from birth to age 32, established that childhood self-control predicts adult financial planning, criminal involvement, substance use, and physical health. The effects held even after controlling for IQ and family socioeconomic status, and even within sibling pairs.

What does a half-standard-deviation gap actually mean at the child level? In a kindergarten classroom, it might look like a child who has more difficulty waiting for a turn, following multi-step directions, transitioning between activities, or staying with a task that does not provide immediate feedback. In a third-grade classroom, the same gap might show up as difficulty completing independent work, organizing materials, planning a multi-step project, or shifting attention from one subject to another at the bell. At the population level, it is a shift in the distribution of these skills downward by roughly twenty percentile points for the affected age group.

When researchers identify a population-level disruption to executive function development of this magnitude, they are not identifying a narrow academic problem. They are identifying a developmental input that will affect how a generation navigates every domain of adult life.

What the Studies Do Not Tell Us

The three studies share several limitations worth noting honestly.

First, all three are correlational rather than causal. The studies document an association between the pandemic-affected developmental window and weaker executive function skills, but they cannot directly establish that pandemic disruptions caused the gap. Other concurrent factors, including changes in screen time, family stress, healthcare access, air quality, and parental mental health, may have contributed. The Wright cohort’s finding that families with greater COVID-related disruption had children with lower executive function scores points toward family stress as a mechanism, but it cannot rule out shared underlying factors.

Second, the studies do not establish a clean dose-response relationship between specific pandemic disruptions and specific cognitive outcomes. The variables that distinguish heavily affected children from lightly affected ones, school closure duration, remote learning quality, household composition, parental working conditions, are all confounded with one another in observational data. Untangling which features of the disruption mattered most will require either natural experiments or interventions.

Third, executive function measurement in early childhood is genuinely challenging. The construct is multidimensional, and different assessment tools tap different sub-skills. Cross-study comparison is complicated by the use of different measures, age ranges, and analytical approaches. The convergence of findings across the three studies, despite their methodological differences, is what makes the overall pattern compelling. No single study is definitive, and the field will need additional cohorts to confirm the trajectory.

Fourth, the trajectory of recovery remains uncertain. The studies document a persistent gap as of the most recent assessment points, but whether that gap will close, hold steady, or widen as affected children move through later school years is not yet known. The Harvard, Tulsa, and East Anglia cohorts will all continue producing data over the coming years. Developmental researchers will be watching closely.

What Researchers Are Recommending

The authors of the recent studies have been careful to frame their findings as a call for systemic intervention rather than individual remediation. The Harvard team noted that early disparities in executive function predict later challenges in health, academics, and behavior, and concluded that supporting children’s skills should be a priority of pandemic recovery efforts, investments, and resources.

“Our research joins others in recognizing that the systemic challenges of the pandemic require systemic solutions,” the Harvard author team said.

What systemic intervention would look like in practice remains an open question. The evidence base for executive function interventions in young children includes structured early childhood curricula like Tools of the Mind, classroom-based instructional approaches that explicitly target inhibitory control and working memory, mindfulness-based programs, and targeted skill-building delivered by trained specialists. The new research suggests that whichever interventions are deployed, they will need to operate at a scale that matches the scale of the disruption, reaching the full affected cohort rather than only the children traditionally flagged for support.

Jones and Dermody, in interviews with parent-facing media, have emphasized that the news is not a verdict. “Consistent, predictable, responsive, and warm environments and experiences are important for sustaining children through challenge and for fostering and supporting their executive function development,” they noted. Parents can help children practice these skills at home. Schools and other learning environments can help. The findings describe a starting condition, not a destiny.

The University of East Anglia team has emphasized the specific value of the school environment for executive function development, given the cohort effect they identified. Children whose first year of school was disrupted by lockdown were the most affected. Protecting and strengthening early school experiences, particularly the social and routine-based features that the UK study highlighted, may be among the highest-leverage interventions available.

What This Means for Schools and Families

For schools, the research strengthens the case for explicit attention to executive function as a curricular and policy priority, not an incidental byproduct of academic instruction. Schools that have been treating post-pandemic academic deficits primarily as a reading and math problem may be addressing the symptoms while missing an underlying cognitive driver. The Tulsa cohort’s finding that teacher perceptions and direct task data sometimes diverge also has practical implications: schools relying solely on teacher rating scales to identify children who need executive function support may be mis-targeting their interventions.

For families of school-aged children, particularly those who have noticed their children struggling with planning, organization, follow-through, and self-regulation in ways that feel out of proportion to typical developmental ups and downs, the research provides context. The struggles many families have observed are not isolated, and they are not the result of parenting failures during the pandemic. They reflect a population-level developmental disruption.

That context does not by itself produce solutions. But it does reframe the problem. The question is no longer whether children’s executive function was affected by the pandemic. Three studies, two countries, and roughly 3,900 children worth of direct, repeated assessment have answered that. The questions now are how large the affected population is, how durable the deficits will be, and what interventions can operate at the scale the disruption requires.

Those questions will define the field’s research agenda for years.

The Three Studies at a Glance