We all have expectations about how the how the world should look, feel, smell, taste and sound. These expectations act as predictions to guide us when we are uncertain, and signal when something out of the ordinary is happening. My work uses computational models, pharmacology and brain imaging to understand how humans learn to build adaptive expectations about the world around us, other people and ourselves. The aim is to understand how and when predictions are realised in the brain, how these mechanisms develop in babies and how they might underlie individual differences in how the world is experienced by people with neurodevelopmental and neuropsychiatric conditions.