Nonlinear dose–response effects of mentor visits in a South African early child development program.

= 4.1, 55% female). At each home visit, mentors assessed caregiver intervention fidelity, emotion reminiscing, and the home learning environment. Biannually, caregivers self-reported hope and social support. Nonlinear mixed models indicated a dose-response effect on emotion reminiscing and home learning environment, plateauing at one visit per month. High-fidelity caregivers plateaued less, and benefits were amplified for low-support and high-hope caregivers. Our findings support the importance of one visit per month, increasing fidelity, tailoring support levels, and caregiver hope initiatives for maximizing program impact. (PsycInfo Database Record (c) 2026 APA, all rights reserved).