What are the comparative effect sizes of early childhood educational interventions across different age groups and learning domains?

Early childhood educational interventions demonstrate varying effectiveness across domains, producing effect sizes of 0.10-1.45 standard deviations for cognitive outcomes, 0.18-1.22 for mathematics, 0.10-0.44 for language (up to 1.10 for literacy), and 0.19-0.56 for socioemotional and motor development, with comparable benefits observed across preschool and infant age groups.

Abstract

Early childhood educational interventions yield effect sizes that vary by learning domain, intervention modality, and age group. Studies targeting cognitive outcomes report gains ranging from 0.10 to 1.45 standard deviations—with intensive, multi-year programs (e.g., Ramey and Ramey, 2023) achieving the largest benefits—while language-focused programs generally produce improvements of 0.10 to 0.44 standard deviations, with some literacy interventions reaching 1.10. Mathematics interventions typically exhibit effects from 0.18 to 1.22 standard deviations, especially when curriculum-based and structured (as in Yıldız et al., 2025 and Clements et al., 2011). Socioemotional and motor development interventions tend to yield modest gains (approximately 0.19–0.56), a range further supported by evaluations of responsive caregiving and physical activity programs. Most studies concentrate on preschool-aged children, though interventions for infants show comparable benefits. Greater intervention intensity, duration, and multi-component design are associated with larger effects, according to the reported findings.

Methods

We analyzed 40 sources from an initial pool of 997, using 8 screening criteria. Each paper was reviewed for 6 key aspects that mattered most to the research question.

Data extraction

We asked a large language model to extract each data column below from each paper. We gave the model the extraction instructions shown below for each column.

Study Design Type:

Identify the specific type of study design used. Look in the methods section for precise description. Categorize as:

• Randomized Controlled Trial (RCT)
• Quasi-experimental study
• Comparative study
• Longitudinal study

If multiple design elements are present, list all that apply. If uncertain, note “unclear” and provide a brief explanation of why.

Intervention Type and Components:

Comprehensively list all components of the educational intervention:

• Primary pedagogical approach (e.g., direct instruction, inquiry-based)
• Specific learning domains targeted
• Additional support services (if any)
• Delivery method (group size, individual/group)

Be as detailed as possible. If multiple intervention components exist, list each separately. Include frequency, duration, and specific content of interventions where mentioned.

Participant Demographics:

Extract the following participant details:

• Age range of children
• Socioeconomic status (if reported)
• Risk factors or special circumstances
• Total sample size
• Gender distribution (if reported)

Use exact numbers or percentages from the study. If a range is given, record the full range. If any demographic information is not reported, clearly mark as “NR” (not reported).

Outcome Domains and Measurement:

List all primary outcome domains measured:

• Cognitive development
• Language development
• Motor development
• Socioemotional development
• Academic achievement
• Other specific domains

For each domain:

• Note specific measurement tools/instruments used
• Record effect sizes if provided
• Indicate statistical significance
• Note follow-up time points for measurements

If multiple measurements exist for a domain, list all with their respective details.

Long-term Outcomes:

Identify and extract any long-term outcomes measured beyond immediate child development:

• Educational attainment
• Employment
• Social relationships
• Health indicators
• Economic outcomes

Record:

• Specific outcome measured
• Age/time point of measurement
• Effect size or key findings
• Statistical significance (if reported)

Geographical and Contextual Factors:

Extract:

• Country or region of study
• Income level classification (low, middle, high-income)
• Urban/rural setting
• Specific contextual challenges or environmental factors

If multiple contexts are represented, list each separately. Use the study’s own classification or standard international definitions for income levels.

Results

Characteristics of Included Studies

Effects

Effect Sizes by Learning Domain

Cognitive Development:

• Effect sizes reported in the included studies range from 0.10–1.45 standard deviations, with larger effects observed in intensive, multi-year interventions (e.g., as reported by Ramey and Ramey, 2023).

Language Development:

• Effect sizes typically ranged from 0.10–0.44 standard deviations, with some studies reporting larger effects for emergent literacy (Barnett et al., 2018: 1.10).

Mathematics:

• Effect sizes ranged from 0.18–1.22 standard deviations, with the largest effects in structured, curriculum-based interventions.

Socioemotional Development:

• Effect sizes were generally small to moderate.

Motor Development:

• Physical activity and fine motor interventions yielded moderate effects.

Academic Achievement:

• Reading and math achievement effect sizes ranged from 0.10–0.60 standard deviations, with larger effects in high-intensity or multi-year programs.

Methodological Factors Influencing Effect Sizes

• Study Design
• Sample Size
• Intervention Intensity and Duration
• Measurement Tools
• Fidelity and Implementation
• Contextual Moderators

Generalizability and Study Context

• Geographical Diversity
• Population Diversity
• Setting
• Long-term Outcomes
• Adverse Effects

Limitations:

• Heterogeneity in intervention types, outcome measures, and reporting limited direct comparison across studies.
• Some studies lacked detailed reporting of effect sizes, statistical significance, or confidence intervals.
• Risk of bias was present in studies with small samples, non-randomized designs, or low fidelity.
• Generalizability was limited by the focus on high-risk and low-income populations in many studies.