Table 1.
Descriptive Characteristics
| Characteristic | Effect Sizes | Studies | ||
|---|---|---|---|---|
| N | % | N | % | |
| Sample Characteristics | ||||
| Outcome Domains (with subdomains) | ||||
| Cognitive | 250 | 70.6 | 107 | 83.6 |
| Academic | 14 | 4.0 | 13 | 10.2 |
| General | 37 | 10.5 | 29 | 22.7 |
| Language | 79 | 22.3 | 52 | 40.6 |
| Literacy | 46 | 12.9 | 25 | 19.5 |
| Numeracy | 28 | 7.9 | 21 | 16.4 |
| Self-Regulation | 50 | 14.1 | 24 | 18.8 |
| Psychosocial | 57 | 16.1 | 35 | 27.3 |
| Behavioral | 25 | 7.1 | 17 | 13.3 |
| Socioemotional | 28 | 7.9 | 23 | 18.0 |
| Physical | 23 | 6.5 | 14 | 11.0 |
| Motor | 19 | 5.4 | 13 | 10.2 |
| Health | 4 | 1.1 | 1 | 0.8 |
| Composite | 24 | 6.8 | 20 | 15.6 |
| Other | 24 | 6.8 | 20 | 15.6 |
| Child Age at Cognitive Stimulation | ||||
| 0–23 months | 109 | 30.8 | 37 | 28.9 |
| 24–47 months | 106 | 30.0 | 35 | 27.3 |
| 48–71 months | 112 | 31.6 | 50 | 39.0 |
| Cognitive Stimulation Measurement Modality | ||||
| Caregiver report only | 274 | 77.4 | 100 | 78.1 |
| Partly or fully observed | 80 | 22.6 | 29 | 22.7 |
| Country-Income Level | ||||
| High | 246 | 69.5 | 91 | 71.1 |
| Upper-middle | 45 | 12.7 | 19 | 14.8 |
| Lower-middle | 38 | 10.7 | 13 | 10.2 |
| Low | 25 | 7.1 | 7 | 5.5 |
| Study Features | ||||
| Data Structure | ||||
| Cross-sectional | 152 | 42.9 | 77 | 60.2 |
| Longitudinal | 202 | 57.1 | 57 | 44.5 |
| Publication Year | ||||
| 2000–2009 | 51 | 14.4 | 18 | 14.1 |
| 2010–2019 | 151 | 42.7 | 58 | 45.3 |
| 2020–2025 | 152 | 42.9 | 52 | 40.6 |
| Study Quality (Low) | 26 | 7.3 | 11 | 8.6 |
| SES as Covariate | 290 | 81.9 | 107 | 83.6 |
Note. SES = socioeconomic status. The effect sizes presented in this table represent associations from different original metrics, including standardized and unstandardized regression coefficients, Cohen’s d, odds ratios, partial and bivariate correlations, and F-statistics. There are 354 effect sizes within 128 studies, with an estimated 442,749 children (M percentage female = 49.0%, range = 0% – 98%; M age = 36.03 months, range = 3.5 – 71.5) in the sample. Twenty-seven effect sizes had missing data on child age. Percentages in the studies column may sum to more than 100 due to studies that included effect sizes with different characteristics.