The disposition to believe what others communicate, or epistemic trust, plays a central role in humans’ learning and cognitive development. It is crucial for the transmission of scientific, historical, technical, moral or religious beliefs. It also lies at the heart of schooling, by supporting the transmission of knowledge from teachers to pupils. This project aims at determining the foundations of this form of trust, uniquely developed in humans, during infancy. To address this issue, this project will use a combination of electrophysiological and behavioural methods (eye-tracker, touch screen, EEG), associated with rigorous and systematic observations of children’s linguistic environment. The project will test key populations to tease apart the contribution of pre-programmed maturation and of environmental factors in shaping trust. Three complementary work packages will investigate the (i) maturational and (ii) environmental bases of trust in communication during infancy, (iii) its motivational origins, and its relation to external rewards and (iv) how it develops in adverse conditions. Altogether, the project will illuminate the sources of humans’ reliance on communication, and its unique role in learning.