The brain continuously interprets signals from the internal organs, yet these signals are noisy and their psychological meaning depends on context. Interoceptive inference offers a computational framework for understanding how prior beliefs and sensory evidence combine to shape bodily experience, emotion, and action. In this lecture, I will show how this framework can be tested experimentally. First, I will outline theoretical developments that treat interoception as an organ-specific and context-sensitive inferential process rather than a single general ability. Second, I will present advances in measuring cardiac, respiratory, and gastric signalling, including psychophysical tasks and neuroimaging approaches that separate perceptual sensitivity, bias, and metacognitive awareness. These methods challenge simple accounts linking “interoceptive accuracy” to mental health and reveal how bodily rhythms influence perception and affect. Finally, I will discuss pharmacological studies that manipulate peripheral bodily states and neuromodulatory systems, providing causal tests of how brain–body signals contribute to interoceptive experience. Together, these approaches move the field from broad associations towards mechanistic models of how the brain interprets the body to construct feeling and emotion.